‘quick view’ comparisons of casting materials

I’ve done quite a bit of work on my ‘quick view’ comparisons of casting materials in the casting section of the Materials menu. This is just text, and focuses on the essential technical information needed .. especially if in doubt as to which material to go for. It’s a lot of text! .. I’m working on posts with less text, and some nice pictures, which will be coming very soon, I promise! To be honest, my main reason for reproducing the whole thing here rather than just writing ‘go and look at it if you want’ is so that I can tag it properly for internet searches which one can’t do with ‘pages’ on the wordpress.com version.

The following is a combination of the easy-reference tech info sheets we provide for our Modelling, mouldmaking and casting course and for the mouldmaking/casting day on the Model-making Techniques course with a lot more added .. because there’s more space on digital paper! The ‘pros and cons’ for each material are generalised and, because there are many different brands with differing properties, they may not apply equally to all of them. The ‘featured materials’ are mainly those we either use or refer to on the courses. Example prices for the materials are from April 2014 and they are adjusted to include VAT. Full addresses for the suppliers can be found in the Suppliers section. Mixing ratios and properties are based on current use, but always check info supplied with product when bought in case of changes.

Prices will be updated each year and more information will be added when it’s significant.. for example, when I start using epoxy resin, which I’ve had to omit from this list for the moment.

See lexicon for explanation of special terms if needed (some anticipated ones are written bold). Often you will see reference made to curing rather than setting, ‘becoming hard’ or ‘drying’ in normal language. This is the proper term for describing the setting and hardening process when two or more parts of a material are mixed together and undergo a chemical change. ‘Drying’ is what water-based materials do when they just harden by the slow evaporation of water in them. ‘Setting’ is what jelly does when the long molecules start to connect, turning it from a liquid to a solid. With ‘curing’ .. usually once a material has cured the change can’t be reversed.

Manufacturer’s ‘use by’ dates just need to be taken with a big pinch-of .. ‘under advisement’! I wouldn’t say they can be ignored, but they are really just an indication of the general time period during which a material will behave as it’s supposed to. I regularly use materials twice, three times or even more than their recommended shelf life with no major problems. Often all that happens is that mixing/working time .. the pot life .. or setting/curing times are different. If in doubt or if the job is important always test some of the material first. Always date a material visibly on the packaging as soon as you buy it together with a note of the recommended shelf life, just so that you can anticipate if there will be changes.

Polyurethane resin

Advantages very fast-working (average 3-4mins pot-life and 30mins demould). Choice of unfilled or pre-filled brands (i.e. already with a certain amount of inert filler material). Stronger than plaster especially for delicate or hollow castings, safer than polyester for indoor work. Less brittle than polyester, good tooling .. i.e. sanding, cutting afterwards whether by hand or with machine tools. Opaque when set .. usually ranging from white to light-beige. Easy 1:1 mixing (can be by volume in some cases, but usually should be by weight). Low odour. Low viscosity (i.e. most types thinner than liquid plaster or polyester) making ideal for filling intricate moulds. Very good detail reproduction. Variety of types ( i.e. very low viscosity for detailed work, slow-set for ‘slush’ casting, semi-flexible versions etc). Useful longer ‘green stage’ before complete setting for trimming and bending. Some resins can be heated after curing for heat-bending, but usually only thinner sections. Fewer contamination issues (less tackiness). Good mixing with a variety of inert fillers if needed e.g. Fillite, marble dust, metal powders etc. Takes powder pigment well though colour is muted on curing. Clean-up uncured PU resins with meths or acetone. Higher temperatures (including deliberately warmed moulds) can speed up curing, lower temperatures will slow down.

Many polyurethane resins start transparent but turn opaque on setting. This has an advantage because trapped air bubbles can be spotted and dealt with in a shallow mould before the resin turns.

Mix using disposable plastic ‘party’ cups and hold the cup palming the bottom. Mix thoroughly but quickly and stop to pour as soon as there’s a hint of warmth from the cup. Small amounts should not need much more than about 10secs thorough mixing.

Not so good Very short working time and sudden cure .. practise needed in timing for mixing and pouring. Not cheap (av £15 per kg and not usually available in bulk amounts, except from Tomps .. although it does seem that more firms are offering larger amounts these days). Always necessary to thoroughly shake-up containers before use. Transparent versions exist but not really an option for home-work due to toxicity! Discolours in time (no UV blocker available). Cannot be made thixotropic (except through addition of fillers). Some resins have difficulty curing in very small amounts or cast in very thin sections. Cans or bottles supplied in are not suitable for pouring small amounts from! .. decant amounts of both parts into plastic cups first. Cans for parts ‘A’ and ‘B’ are usually identical except for labelling and with identical lids .. mark these ‘A’ and ‘B’ to avoid getting mixed up. Uncured resin is not regular domestic waste and has to be taken to recycling!

Using too much of the hardener part (this is most often part ‘B’, the thinner of the two liquids. With EasyFlo it’s part ‘A’ though) can lead to persistent greasiness on the surface of the cast. Always try to dose accurately 1:1 by weight unless the product directions state otherwise. The greasiness can go in time or the cast needs to be scrubbed in lukewarm water and detergent.

Featured materials

Fast Cast polyurethane resin £9.59 per 500g kit, £25.18 per 2kg, £97.08 per 10kg (tomps.com) Extra-fast and extra-thin PU resin (Tomps claim that the viscosity is as low as 40cps but it’s actually a little over 50 .. still very thin though!), pot-life 3-4mins, demould after 30 mins. Slower version pot-life 7-8mins, demould after 1 hour (this is unusual, patience is needed before demoulding). Cured colour pale beige. Has a low viscosity because it comes unfilled. Shore D 72 when fully cured. Manufacturer’s recommended shelf life 6 months. Read MSDS supplied on Tomps website .. Part ‘A’ classed Xi Irritant, Part ‘B’ classed Xn Harmful.

EasyFlo 60/120 £28.80 per 1.9kg (4D), £24.62 per 1.9kg/£96.53 per 10kg(mouldlife.net). Made by Polytek. The numbers in the names of the different types denote their viscosity in cps. EasyFlo 60 has a very short 2min working time and just 15min demould. EasyFlo 120, the thicker one, is specially designed for ‘slush’ or rotational hollow casting, 2min working time, 15-30min demould. Cured colour opaque white. SG when mixed 1.03. EasyFlo is noticeably more ‘plastic’ i.e. a little more flexible when cured than other polyurethane resins. The big difference to note with EasyFlo is that it can be mixed 1:1 by volume and if by weight needs to be mixed in the ratio of 100A:90B! Shore D 65. The manufacturer recommends meths as a cleanup agent and shelf life of 6 months. Read MSDS supplied on Mouldlife website .. Part ‘B’ classed Xi Irritant, Part ‘A’ classed Xn Harmful.

SIKA Biresin G26 £38.27 2kg (Tiranti) I’ve used this on-and-off for a long time and it has always been reliable .. keeps well, flows well for fine detail .. though it is not the cheapest or the thinnest. Unfilled, viscosity 70cps. Normally 3-4min working time and 30min demould but can be sooner especially if taking advantage of ‘green stage’ when resin is still partly flexible but can be demoulded. I’ve found that G26 has a longer green stage than other resins tried. Cured colour light beige, Shore D 70, SG mixed 1.1. Manufacturer’s recommended shelf life 12 months. Read MSDS supplied on Tiranti website .. Part ‘A’ classed Xi Irritant, Part ‘B’ classed Xn Harmful and ‘dangerous’ with some evidence of a carcinogenic effect .. hmm, this I keep forgetting!

Fillite with PU resin £4.56 1kg, £14.10 5kg (tomps.com); £43.20 25kg (specialplasters.co.uk) An expanded ash material, a popular filler for resins. Resin will generally accept up to 4x its volume of Fillite without affecting setting process but the mixture starts to become too thick to pour easily after about 2x. If using any filler with resin, care should be taken to keep the filler completely dry i.e. always in sealed containers, away from atmospheric moisture, otherwise it can cause the resin to foam. Fillers are commonly used with resins for various reasons .. to economise; to make the casts either lighter or heavier; to make resin harder or softer; to impart a colour or appearance; to thicken for making hollow shell casts, etc .. Normally the filler is mixed thoroughly into one part of the resin, part ‘A’, before the measured amount of part ‘B’ is added. If you are adding filler to achieve a specific thickness and want more control over that, measure out both resin parts and mix filler into both before putting them together. Mixing filled resin parts needs more thoroughness to properly distribute them!

Polyester resin

Advantages Inexpensive (esp 5kg upwards, as little as £6 per kg). Available (many suppliers), and good literature/info on the web. Versatile (different types e.g. general-purpose, gelcoat and clear casting) and can be made thixotropic. Very strong (esp. with glassfibre reinforcement .. its most familiar use). UV blocker available to combat discolouration. Longer pot-life (compared to polyurethane resin) gives more time for mould-filling or coating (excellent choice for PU foam coating). Takes powder pigment and small amounts of standard artist’s oil paint well for colouring without affecting cure. Choice of catalyst addition (standard 1% but more can be added when mixing small volumes to ensure curing). Some ‘GP’ versions are modified for less styrene emission. Best choice, because transparent, for colouring or filling with metal powder for ‘cold metal’ casting.

Not so good  Work should only be carried out when indoors under proper extractor fan conditions (never at home) and using respirator masks. Strong exothermic reaction may cause cracking in larger volumes (add less catalyst). Some types more prone to surface tackiness (oxidisation). Tends to be brittle on its own compared to polyurethane resin. Vaseline should not be used as barrier, and polyesters are affected by contact with moisture/water.

Featured materials

Tiranti’s polyester resins multi-purpose £9.26 per kg; general purpose £9.25 per kg; gel coat £11.39 per kg; clear casting AM £13.63 per kg (Tiranti). Gelcoat can be catalysed adding 2% whereas MP, GP and clear should use just 1% for large solid castings (but up to 4% can be used to accelerate small castings). Pot-life c. 20mins. At 2% catalyst MP can be safely demoulded in less than 2 hrs but allow 72hrs-1week for full setting.  If barrier/ release is needed (not normally necessary with silicone or vinyl) use polyvinyl alcohol or rape seed oil.

Cold metal casting metal powder c.£10-£12 per 500g average (tomps.com, Tiranti) Up to 4:1 metal powder to resin (by weight) can be mixed to make surfacing layer with either MP or clear casting resin, catalysed 2% (always add catalyst to resin in this case before mixing in metal. If proper gelcoat resin is used less metal can be added, c.2-3 parts metal by weight. Less than 2:1 is ineffective. Wait until rubber-hard, then fill rest with normal resin catalysed 2% for small forms (1% for larger). This can either be unfilled or if preferred, dark pigmented. Wait at least 72 hrs before ‘cutting back’ and buffing (cutting back is abrading the surface i.e. with steel wool to expose the metal particles properly). Note: Tiranti’s ‘rule of thumb’ is same volume of metal powder to resin plus ‘a little more’ metal powder, and they advise that if measuring by weight the content of metal powder to 1 part resin is; Aluminium 1.25, bronze 6-7, brass 5-6, copper 4-5, iron 6-7

Fibreglassing

Chopped strand mat standard 300gsm £1.62 sq metre (specialplasters.co.uk) £2.94 sq metre (Tiranti). Matting used in conjunction with MP or GP polyester resin (do not use clear casting resin) for fibreglass lamination.

Just 1 soaked layer of 300gsm matting may be more than strong enough for a small form i.e. up to 20cm; over that 2 layers up to 40cm, and larger than that 3 layers. This is a rough estimation and it depends of course on whether the object will be load-bearing or not.

Plaster

Advantages Cheap (i.e. even a high quality plaster may be as little as c. £20 for 25kg from the right suppliers). Suitable for solid pouring of medium to large-size forms. Available (many suppliers), and good literature/info in print and on the web (established material with very long tradition). Reliable i.e. not easily contaminated and long shelf-life if properly stored. Easy to mix (with some care and practise). Health&safety friendly. Extensive range of brands with varying properties and uses (differences in fineness, hardness, setting time etc). Choice of fine, dense, hard ‘alpha’ plasters or softer, more porous ‘beta’ plasters. Best to use fine casting plaster (with recommended ratio 2.5-3parts plaster to 1part water, i.e ‘alpha’ plaster, for most work, i.e. not just casting but mouldmaking, except when doing absorption castings.

Not so good Surface air bubbles and water drainage lines on casts are often an issue (moulds can be sprayed with a surfactant to combat these). Not as ‘free-flowing’ as resins and certainly not as tough for casting small, slender forms. Not as easy to patch or repair. Weighing scales needed if following recommended ratios by weight. Small amounts sold in craft or hobby shops are vastly overpriced usually with no supporting information re. type (whether ‘alpha’ or ‘beta’) or optimum mix ratio etc.

Featured materials

Prestia Expression casting plaster £20.08 per 25kg (specialplasters.co.uk). Fine, hard ‘alpha’ plaster. Mix by eye (but recommended optimum mix 2.5-2.6kg per litre water). Water volume will constitute approx ½ final volume. Working time 8-10 mins. Can be demoulded after c. 30mins, or after top water has been reabsorbed.

Crystacal R casting plaster £24.49 per 25kg (specialplasters.co.uk). Similar to above but even harder and stronger. Recommended mix for maximum strength is 2.86kg per litre water, but this mix does not pour well (2.2-2.5 makes more pourable mix). Pot life 10+mins, setting 15-20mins, demould 30+mins. Slightly longer working time makes this a good plaster for building up mould jackets using its intermediate ‘cream cheese’ state, but one has to work fast.

Basic Alpha £8.29 per 5kg, £21.26 per 25k (Tiranti) Good quality casting plaster, fine and hard. Working time approx. 12mins, set hard in 25mins. Recommended mix 2.8kg per litre water.

Colouring of plaster For calculating beforehand how much pigment can be safely used, at max 10% by weight .. If 100ml of final mix is needed, this will require roughly 100ml of plaster and 50ml of water. Plaster has a generalized SG of 1.2 so the weight of the mixture will be 170g. So up to 17g of pigment can be added in theory before affecting setting. No special pigment needed .. standard powder pigment will do.

Polymer-modified plaster

Advantages A good ‘alpha’ plaster can be mixed with acrylic polymer liquid in place of (or occasionally in addition to) water which makes casts much stronger and even ‘weatherproof’ for outside sculpture. The resulting mix can also be used in place of resin with glassfibre matting or other reinforcement to build or cast very durable shells. The mix generally has a longer working time than plaster/water (i.e. can be 20-30mins as opposed to 10-15mins) and it can enable finer, more detailed castings. ‘Jesmonite’ is one popular brand, usually sold as a system, but acrylic polymer liquid can also be bought on its own, i.e. from Tiranti, for use with any alpha plaster.

Not so good More expensive than using the plaster on it’s own (i.e. Jesmonite ‘kit’ comprising 3kg plaster plus 1kg liquid is c. £25). Mixing needs to be very thorough (power-assisted mixing recommended for large amounts). Mix much more prone to air bubbles (leave to stand a little).

Featured materials

Plaster/polymer mix polymer liquid £9.25 per 1kg, £35.34 per 5kg (Tiranti) Only with ‘alpha’ plasters, generally 3:1 plaster:polymer by weight.  Up to 10% more polymer or water can be added to thin the mix.

Jesmonite £25.60 per 4kg kit (4D), £60.00 per 20kg kit (canonbury arts). Mix 2.5-3parts powder to 1part liquid. Different Jesmonite types e.g. AC100 (general-purpose)

Latex

Advantages As a flexible casting material in special cases but normally only when applied in thin layers and better using an absorbent mould such as plaster (latex is an ideal material for the absorption casting method). Also ideal for creating flexible ‘skin’ surface casts. Good detail reproduction. Relatively inexpensive (c £10 per litre). Can be used as it comes, no mixing needed. Durable and long-lasting, with a surprisingly high tear strength. Can be thickened (special additives available). Latex is readily available (many suppliers, inc. hobby and art shops). No serious health&safety issues. Can be coloured (using small amounts) with any water-based paint.

Not so good Cannot be poured as a ‘mass’ into a non-absorbent mould (such as silicone) because it sets by evaporation of water content .. it will never dry! Can only be applied in layers, each of which needs to dry first before applying the next. Drying is slow unless mould is absorbent. Will shrink up to 10%! Surface painting of dried latex poses some problems (best methods are either to mix acrylic paint with Prosaide or use Humbrol enamel paints). Latex casts need a good dusting of talc to stop them sticking together. Latex is not compatible with petroleum jelly i.e. Vaseline, so this cannot be used as barrier/release agent.

Featured materials

£11.30 per kg (Tiranti), £11.00 per kg (Canonbury Arts)

Prosthetic silicone

Advantages Very soft, ultra-flexible silicones (with a low Shore A value) such as Platsil Gel 10 or 00 can be cast to make prosthetic forms or bendable animation puppets. These silicones are usually translucent and will accept small amounts of acrylic or oil paint as colourant. Can be made even softer with addition of special ingredient i.e. ‘Smith’s Deadener’ for Platsil range. Usually addition cure (1:1 mix) and much faster curing. Usually high tear strength. No noticeable shrinkage.

Not so good These are generally more expensive than other silicones. Fairly viscous, may not be pourable (more likely ‘spreadable’). Not compatible with ..sulphur-based plasticines, latex, condensation cure silicones, set addition cure silicones, some resins .. i.e. fairly long list of known inhibitors, including garlic! If additional surface painting is required this is either not easy, or requires specially marketed sfx paints which are quite expensive.

Featured materials

Platsil Gel 10 £58.10 per 2kg (4D) also available from mouldlife.net. Mix parts 1:1 by weight or volume, approx. 6min working time, brushed into mould (too viscous to pour easily), 30min demould. Can be coloured with small amount of acrylic or oil paint mixed in (unbelievably, oil paint doesn’t affect it).

Polyurethane foam

Polyurethane foam is available to buy in the form of two liquids which when mixed together start to foam, expand and solidify to fill a space a number of times larger than their initial volume. There are so-called ‘self-skinning’ foams which develop a less porous outer skin, and there is also the choice of rigid, brittle-setting foam or flexible types similar to cushion foam. If the right amount is mixed quickly and poured into a mould which is then securely closed the foam will expand to produce a cast of the form. This works well for fairly simple shapes but not for constricted ones and there is a limit to how much surface detail is reproduced.

Featured materials

Self Skinning Flexible Polyurethane Foam £38.88 per 3kg (Tiranti) Mix Parts ‘A’ and ‘B’ in ratio 2:1 by weight. Expands 5-6 times volume. 5mins to rise, 15-20mins demould. Cures white. Special H&S care needed against breathing in Part B ‘harmful by inhalation and contact with eyes’.

Update to ‘modelling wax’ info page

At the moment I’m working on a number of new posts, after quite a long time not being able to write because of teaching, and these will include .. methods of hollow casting in enclosed moulds i.e. not needing a pouring hole; basic working with Jesmonite; making a ‘strengthened’ silicone rubber mould i.e. not needing a supporting jacket .. all these are coming soon! But for the moment I’ve updated my modelling wax info page in the Materials section, because using the soft ‘Terracotta’ modelling wax for mould setup proved so successful during a recent Modelling, mouldmaking and casting course that I wanted to note it there, and include it as a post here! My additions to the modelling wax page also include the results of some tests I made on how to dissolve i.e. clean up modelling wax, and I’ve updated current prices etc., but here is a transcript of the part dealing with mouldmaking preparation:

Tiranti’s ‘Terracotta Wax’ is by far the best option I’ve found so far for mouldmaking setup .. i.e. either for embedding a prototype form half-way to create the first part of the mould, or for building temporary containment walls.

In the first place the wax is ready to use without too much ‘conditioning’ between the fingers .. it becomes very soft almost immediately. In the past I used standard plasticine (the Newplast type, in the long cellophaned packets) by default, and although this generally worked well enough it took a while to make soft enough to work with comfortably. Also, when it stuck to prototypes it was very stubborn, taking a lot of time and effort to remove it completely. Often (though not always) when silicone rubber was cured against it, residues of plasticine would remain like a crust on the cured silicone surface and again, although this could be removed it could take a lot of time and effort.

In a recent run of our Modelling, mouldmaking and casting course we gave all of the students ‘Terracotta Wax’ for embedding or setting up and on dismantling the first mould halves (in order to start the next) the wax came free like a dream and hardly any time was needed for cleaning up! I recommended a particular method though, which I want to illustrate here using photos of a similar setup I made yesterday.

setting up for mould jacket_1

The example above is, in this case, not the initial prototype form as you can see .. this has already been covered with silicone rubber and the setup here is for making the plaster or Jesmonite jacketing (also often called mother mould) to support the silicone part .. but this will still serve as illustration. The object first needs to be just securely rested on a baseboard in a sausage-ring of wax (note .. the baseboard must be large enough to accommodate all subsequent stages i.e. if this were the initial prototype the baseboard must be large enough for the silicone layer and then, later, making the harder jacket parts. Generally, for medium-size forms like this, 5-6cm space around should be enough). It is important that the object is just resting securely in the wax i.e. there is no need to press the wax forcibly into the object’s surface at this stage, just make sure that the object cannot move around.

setting up for mould jacket_2

This ring is then built up, as above, keeping the contact between object and wax to a minimum. Below, when the ‘embedding line’ is reached, i.e. the line around the object which is meant to serve as a smooth barrier or containment wall, the topmost wax can be pressed and smoothed against the object’s surface. It only needs just a few mm of contact, as long as this layer is properly supported by the wax built up underneath. I’ve found that modelling wax, at least this particular one, can be smoothed much more readily with clean metal tools, tending to drag a little against the wooden ones. The most important factor at this stage is a ‘watertight’ seal between the wax wall and the object’s surface. This kind of barrier or containment wall just needs to be as smooth as shown i.e. certainly not perfectly!

As with the baseboard, a little forward-thinking is needed. The wax platform needs to be wide enough all-round for whatever will be applied to it i.e. in the case of starting with the initial prototype, both the silicone layer and then the subsequent mould jacket. But, unlike the baseboard, at least the platform can be extended later if need be.

setting up for mould jacket_3

Below, I have pressed natch marks in the wax around the form using a ball-headed modelling tool (these can often be found in modelling tool packs for cake decoration). These natch marks should not be too deep! Whatever material is going on top will reproduce these marks (and transfer corresponding ones to the other side of the mould when made) and they are simply there to locate the finished mould halves together properly. I’ve found that the modelling wax sticks much less to tools than plasticine, though about the same as Super Sculpey.

setting up for mould jacket_4

The final task in this setup is making a small vertical containment wall around the natch marks. For medium-size forms around 1cm distance from the object is sufficient. In this case building a wall was necessary because I was planning to start the mould jacket by pouring Jesmonite over the form.

‘Terracotta Wax’ sticks very readily to itself, much more so than either plasticine or especially Super Sculpey, partly perhaps because of its extreme softness! It was only necessary to press this wax strip lightly onto the platform to establish a proper seal. I’ve found the most effective wall is made by flattening a rolled strip of wax first (by pressing and turning over a few times) and then trimming the edges to a flat right-angle with a scalpel.

On the whole no release coatings are needed with this wax. It releases well from a variety of materials even if rough or porous, as long as it’s not deliberately worked into the surfaces. Most importantly silicone rubber will cure and detach cleanly from it. I have found that if Jesmonite is poured onto it and the mix is ‘polymer rich’ i.e. towards 2:1 powder to polymer liquid (the standard recommended for economy is 3:1), the wax can adhere to the cured Jesmonite in some places. But if this happens the wax is very easy to scrape off.

setting up for mould jacket_5

setting up for mould jacket_6

Tools for measuring and marking-out

This is the first part of an account I’m putting together of tools I’d recommend for small-scale making. Once completed each part will be previewed as a post and then put in the Methods section under Recommended tools for small-scale making where I can add to them as I learn new things. The tools will be grouped according to general tasks .. measuring and marking-out; cutting; assembly; shaping and modelling; creating surfaces; painting.

I’ve collated these accounts together from what I’ve already written on this site or elsewhere, but I’ve also added quite a bit to them. The list includes some simple, custom-made tools which can’t be bought, and I’ve added more information on where others can be found. Obviously this list reflects the way I prefer to work, which may differ from other people .. I prefer to use hand-methods rather than machine tools on the whole, but I’ve also kept to the use of hand-tools in my teaching because most of the people I teach don’t have power tools or workshops.

A tool is any device, however simple or however complex, which enables or contributes to the performance of a task .. in this case the task of making. Even temporary constructions to assist assembly, or one-off templates to achieve a specific shape, are tools, and that’s why I’ve included them.

This first part deals with tools for measuring and marking-out and deals with pencils, rulers (including scale rulers), squares, small drawing-boards, spacing or shape templates and other geometry tools. It also covers tools for weighing or dosing materials.

Mechanical pencil

This is the usual name for it now .. a very thin graphite stick or ‘lead’ housed in a mechanism which allows it to be advanced forward as it wears down, without the need for sharpening .. but I’ve also seen ‘automatic’ or ‘clutch’ pencil referred to, and in the UK the old-fashioned term ‘propelling pencil’ is still sometimes used. Some luxury versions can be expensive, but others are as cheap as £4-5 for a pack of 10. These more general-purpose ones most often have a 0.7mm lead with a standard ‘HB’ hardness and it’s also usually possible to refill them.

mechanical pencil

It is essential to use one of these for fine-scale work, to make a consistently even, fine line when marking-out for cutting etc. But this doesn’t need to be an expensive one .. the cut-price ones from supermarkets will do almost as well. I personally prefer to use a special type though which takes a 0.3mm ‘H’ lead, finer and harder than the usual ones, which gives better accuracy. But I always try to keep this at home, and use other cheaper ones out-and-about or for other general-purposes because pencils are notoriously easy to lose!

Where to get and what they cost

Ryman £4.99 for pack of 10 ‘Papermate Non Stop Mechanical Pencils’ 0.7mm lead; Rotring Tikky 0.5mm £3.99; Zebra Drafix 0.3mm £4.99

Tesco £5.30 for pack of 10 ‘5 Star Disposable Mechanical Pencil’ 0.7mm lead (three leads included with each)

keeping track of measurements

Metal rulers

I deal with these both here and in the next part on tools for Cutting because they are used as much to assist cutting as for measurement. In fact, I hardly use the smaller metal rulers for anything else since the markings on the scale ruler, above, are much clearer to read than the reflective surface of steel rulers. Metal rulers are not generally expensive, although the ones which have a nicely finished edge (smooth and with the raised burr taken off) often cost a bit more. The extra cost can be worth it .. cutting is made easier because there’s less friction between the metal edge and the scalpel blade.

metal rulers

Over the years I’ve come to rely on having four .. a broader 1metre aluminium ruler and a 60cm flat steel ruler for larger work, a 30cm, and the smallest with is 15cm. Especially when cutting, it is useful to have the smaller ones because they’re much easier to handle and move around when working on small work. The aluminium ruler has a rubber grip on its underside to stop it slipping and I cover the underside of the steel ones with masking tape which works almost as well. In the past I’ve tried rulers lined with cork (which are commonly available), but this raises the marking/cutting edge up too far I find, making it possible to ‘undercut’ with the pencil or knife blade if one’s not careful. I have also tried smaller rulers in aluminium, which are also common, but the soft metal is very susceptible to denting and can even be accidentally ‘shaved’ with the scalpel!

Where to get and what they cost

greatart.co.uk Rumold Stainless Steel Rulers inc. VAT 15cm £1.40, 30cm £2.10, 60cm £12.95, 1metre £24.50. Rumold is a reliable German brand, calibration includes (on one edge) half-millimetre measures. There is a choice of either lighter 0.5mm thick rulers or 1mm thick, varying prices. £16.95 ‘Aluminium Ruler’ 1metre with non-slip plastic base.

Scale ruler

Some very basic reductions in size, such as half-size or ’1:2′ or tenth-size ’1:10′ in metric, can be worked out in-the-head or with a normal ruler, but others such as 1:5, 1:25 or 1:2500 are more difficult. At some point in the past someone had the bright idea that having, as it were, a miniaturised version of a long tape measure to read from would save a lot of time .. and so the scale ruler came to be. Most people who regularly have to model or draw in scale use one of these to avoid mistakes even when the reduction is a simple one.

One can’t get just one type of scale ruler which will enable working in any scale (big or small) and any unit of measurement (metric or Imperial). Instead there are separate types. Usually you will find one type for ‘big’ scales such as 1:10 or 1:25 especially suited to interior design or theatre design .. and separate rulers with 1:12 or 1:24 scales if you work in feet and inches. Then there is the other type for ‘smaller’ scales used in architecture or landscape mapping, such as 1:100 or 1:2500, and these will also have their separate Imperial equivalents. You notice that I refer to a scale that involves less of a proportional reduction in size .. such as 1:10 .. as big and a scale that involves more reduction in size .. such as 1:100 .. as small. This is, I believe, the correct way of referring to them, because we naturally think of a 1:100 model as being ‘smaller in scale’ than a 1:10 model! People can get very confused about these terms though .. and it is usually the result of confusing ‘scale’ with ‘size’. One needs to think about them separately.

1:25 scale rulers

So let’s look at a standard scale ruler suitable for working, for example, in 1:25 scale and see how it helps. Above is the most common and easiest type, a ‘triangular’ rule which is able to present six different scales for us, one on each of it’s six edges.  These scale rulers usually include 1:20, 1:25, 1:50, 1:75, 1:100 and 1:125 ( the 1:100 ‘scale’ is basically just a regular centimetre rule in which the centimetres can be read as metres. In any event it’s useful to have a regular rule included ). The usual plastic type above has a different colour (green, red, black) to assist in finding the relevant face more quickly. I prefer working with this type of scale ruler (rather than the more elegant looking flat type) because they’re less easy to lose amongst the clutter of the work-table! These normally cost between £5 and £10 in the UK at the moment if bought in a shop .. a little less online. The metal one behind it, found in a cheap DIY tool shop, costs a lot less and does its job just as well, but the calibrations wear off a lot quicker because they’re just printed on rather than incised.

Both clearly show the scaled size of 1metre, 2metres and so on .. up to 7.5metres. Both clearly indicate 50cm divisions and the smaller divisions after that represent units of 10cm. The very smallest divisions within those .. this is important to remember .. represent 2cm each, not 1cm since this would be too small to display. With the right scale ruler to assist, working in scale really should be as simple as reading from a regular tape measure.

architectural scale ruler compared

But unfortunately one might have to hunt around a bit for the right scale ruler to use, if you prefer to buy from a shop. Many art or graphic supply shops stock them but there may be more demand for the type shown above (which is also available in the triangular form) which is calibrated for working in much smaller scales. The numbers along the 1:2500 scale above are the number of metres represented and the smallest divisions therefore represent 2 metres. This can be used for 1:25 work in place of the proper scale ruler because the calibrations work out the same .. one just has to think of it as representing centimetres rather than metres. So ’100′ on this readout becomes 100cm in other words 1 metre at 1:25 scale. A lot of people find it no problem to mentally switch, but it’s certainly much easier to misread or make other mistakes using one of these and it certainly doesn’t help that there are also usually two different scales cohabiting the same edge, as you can see here. I would recommend that if you can’t get the ‘quality’ scale ruler in exactly the scale you want it’s better to go online, or go for a cheaper metal one. In the UK I’ve seen these in £shops and Maplin, sometimes Robert Dyas and B&Q.

I’ve mentioned already that the divisions on a scale ruler are much clearer to read than on a metal ruler .. which reflects too much! .. so I almost always use the ’1:100′ on the scale ruler for full-scale measurement (at least, up to 30cm). I generally only have the metal rulers for cutting against.

If you want to read more about working with scale rulers and generally getting to grips with the concept of scale go to the article ‘Working in scale’ in the Methods section.

Where to get and what they cost

amazon.co.uk £4.45 ‘Helix 300mm Metric Triangular Scale Rule’ colour coding, doesn’t list which scales are included, but looks like architectural scales;  £5.49 ‘1:20 1:25 1:50 1:75 1:100 1:125 Plastic Triangular Scale Ruler’ colour coding, looks fairly good quality, distinct scales/easy to read;  £2.22 ‘Silverline Tools 731001 300mm Aluminium Scale Tri-Rule’ distinct scales i.e. 1:10, 1:25, 1:50 etc, not colour coded. This is cheap because the calibrations are just printed on and they will wear off in time!

WHSmith £4.99 ‘Helix Tri-Scale Rule 30cm’ combined scale readouts 1:1 – 1:2500, can be more difficult to interpret.

Staples £5.48 ‘Staples 30cm Scale Rule’ colour coding, combined scale readouts, as above;  £5.59 ‘Linex Triangular Scale’ aluminium, distinct scales 1:1-1:125 not colour coded. May suffer with wear, as above.

Making a customised scale ruler

There are some commonly used scales that you are unlikely to find on any of the manufactured scale rulers .. for example 1:12 standard ‘dollshouse’ scale or 1:6 often used in stop-motion animation. For these scales a normal feet&inches ruler could serve well (and it is partly for that reason that these scales have persisted). But on the other hand this doesn’t ‘serve’ completely, because it’s rare to find a normal Imperial ruler where the inches are divided into twelfths .. and in any case it’s no help at all if you want to measure in metric!

custom scale rulers

In these events it’s good to know that making your own ‘custom’ scale ruler for unusual scales is relatively easy! Above are some examples, and it’s pretty clear how these are done .. by photocopying the surface of a regular scale ruler but reducing or enlarging at a certain percentage. For example, for the customised 1:6 scale above I’ve converted 1:10 calibration (it’s written as 1:100, just ignore that) in which 1cm on the ruler would represent 10cm in the model, to 1:6 in which the same 1cm on the ruler would represent 6cm in the model. The ‘destination’ value i.e 6 needs to be divided into the ‘start’ value i.e. 10, giving 1.666. This is then multiplied by 100 to give the percentage of (in this case) enlargement on the copier, which is rounded off to 167%. This very slight rounding off hardly matters in terms of accuracy. I usually spraymount this onto a card or plastic strip so that it will last. It’s important when using it that you’re very sure about what these calibrations now represent .. for example you might want to mark the ’1, 2, 3 etc’ here as ’10, 20, 30 etc’ to make it clear that they now represent centimetres.

If you want this method of conversion expressed as a kind of formula see ‘Working in scale’ in the Methods section.

Try square

Unless they see it spelt, a lot of people assume that the name of this tool is ‘tri-square’ (and sometimes it’s even spelt that way, which is wrong) .. the ‘try’ comes from an old usage meaning ‘to test’. The try square is both for checking and marking out right-angles. It is absolutely invaluable .. I’d say indispensable .. for checking the right-angles on wall pieces and then drawing up repeated verticals or horizontals for doors and windows, as shown below. It can be used in much the same way as a T-square would be used against a plain drawing-board.

marking out using try square

Never assume that a sheet of card (or especially an off-cut of card) has perfect right-angles even if it’s straight out of the shop. These need to be checked first. Laying a set-square over the corner is often the way that people check but because plastic set-squares are transparent one has to strain the eyes a bit to see this and it may not be sufficiently accurate. Using a try square is a clearer way of checking.

The best try squares for model-making work are the smaller type. The one shown here is more properly termed an Engineer’s Try Square being very precisely and smoothly machined and finished. These will remain true, whereas carpenter’s try squares, often bigger, have a steel ‘blade’ (the part drawn against) and a wooden stock (the part held) and the rivets that bind the two parts can sometimes become loose in time. Try squares are specified by a measurement, sometimes referred to as its ‘reach’, which is the length of the blade not including the stock.The all-metal try square shown here is a comfortable size for small-scale work, with a 100mm blade. For most small-scale work, unless habitually very small, there’s not much point in getting a try square less than 100mm.The most common size for larger try squares is 250-300mm. Bigger than that, and they can become a bit cumbersome to handle.

cutting risers

When buying the cheaper kind of try square (usually medium-size 23-30cm and composite make) I would strongly recommend checking it before buying if at all possible. The best way to check it is to position it against a straight edge of card, draw a line, turn the try square around and check that the blade still lines up with the drawn line. If buying online it helps at least if it states that it has been checked in accordance with BS3322 specification.

With most good-quality try squares the metal of the blade is tempered to make it harder. Some have an angled stock, as shown second from top below, which enables them to be positioned at a 45degree angle for marking mitres (this is more common in the bigger, woodworking try squares). I made the white one myself, cutting a strip of 5mm Palight Pvc for the stock and a strip of 1mm styrene (which is tougher) for the blade. I bonded these together using superglue, positioning the pieces against the corner of the cutting mat for a true right-angle.

assorted try squares

The photo below (from Wickes) shows a so-called combination square. The ‘blade’ in this case is a 300mm steel ruler which can be removed from the stock and used separately. When used as a try square the stock can be positioned at either end to use the 45° angle or the right-angle. It often also has a built-in spirit level. Many of these combination squares are fairly cheap and therefore not finely machined. As a consequence there may be a little too much movement between the two parts and the accuracy needs to be checked.

combination square

Where to get and what they cost

4D Modelshop £6.20 101.6mm all-steel engineer’s try square (Silverline)

Wickes £8.99 ‘Carpenters Try Square’ 150mm. Traditional design with wooden stock; £9.69 ‘Combination Square’ 30cm, cast metal, repositionable, with built-in spirit level (see photo above).

Homebase  £4.99 ‘Try and Mitre Square’ 200mm, yellow plastic stock, steel blade

Small drawing board

It can be very useful to have a small drawing board, i.e. one just large enough for working on A4 sheets of paper. I’m a firm believer in drawing up everything I make, however small, at the very least to test and ponder over the design before starting to make. I usually only need a small area for this but I also want the means of drawing reliable parallels or right-angles, and setting up the larger drawing board just for this is a hassle! Simple wooden boards for this purpose can be bought, but they’re not so easy to find and can be expensive for what they are. A good, solid piece of MDF can be cut to size at, for example, B&Q but there is no absolute guarantee that the edges will be perfectly smooth and straight.

On the other hand small kitchen chopping boards like this one are common and very cheap. I bought this tough polyethylene board at Tesco for about £1. Its corners are true right-angles and the sides are perfectly straight and smooth. The surface is also smooth but masking tape will grab on it for securing a sheet of paper.

kitchen chopping block as drawing board

The try square I am using here for right-angled drawing is a little too big and cumbersome. A smaller one i.e. 300mm would be better. I would advise taking a try square to the shop if you buy a board to check for straightness and smoothness, also a piece of A4 paper and a pencil to test the surface smoothness when drawing. Some types of plastic cutting board have a slightly textured surface, meant to grip better, and it may mean that a sheet of thicker paper should be put underneath the drawing paper when working.

Spacing templates

An example of what I mean by this is shown below. I often work in 1:25 scale but in the past, whenever I needed to do brickwork, I always needed to remind myself about the size of bricks and use a scale ruler to divide up the surface for scoring the pattern. This was unnecessarily time-consuming, each time, considering bricks have remained the same size and patterns for hundreds of years. So after a while it finally dawned on me that I should just invest a little time to draw up some accurate, scaled pattern templates and use these to transfer spacing marks to the surface instead of having to measure up each time. I’ve spraymounted this one to 1mm Pvc so that it will last.

scoring brickwork lines in foam

Shape templates

Most people will be familiar with the circle or oval drawing templates shown below, even if never having used them. Most art or graphics materials shops have them. The small-circle template is particularly useful because there is a limit to how small one can draw with a compass. Oval templates differ, some featuring more ‘pointed’ or thin ovals and some more ‘fat’ or rounded like this one. Most are made from translucent plastic, but there is quite a wide variety in hardness, finish and price! Generally the harder, more rigid plastic type is more durable, but not necessarily the most finished or accurate. Often the transparent, tinted acrylic ones (as below) seem to be the better quality, i.e. from the German firm Rumold.

working with obeche wood

When using the circle template, unless drawing freehand it’s important to define the centre of the circle you want first and draw up a cross from this so that you can position the template exactly over it i.e. with cross positions aligning. To draw the circle you should click just a little extra length of pencil lead out, so that only the thin lead is touching the template and the pencil needs to be kept as vertical as possible while drawing because otherwise the circle will distort.

marking out on Pvc

Especially if you use these a lot and rely on them, it’s very important to care for them. The plastic can be easily scratched or dented and this is obviously not wanted on the inside edge of the shapes. They certainly can’t be used for cutting against without damaging them, no matter how careful you might try to be!

Where to get and what they cost

There’s a wide variety of these so the following is just an indication of price and where to look. It’s better to buy these where you can look at what you’re getting. Because I can’t find the brands anymore of the ones I’ve got I can’t vouch for quality.

amazon.co.uk £2.59 ’8.7″x5.2″ Educational Stationary Template Oval Ruler Guide Clear Green’ fat ovals from 4-42mm long with ‘crosshairs’ marked, green translucent; £1.85 ‘Helix Circle Stencil Template -30 Circles’ from 3-28mm diameter. This is the softer, flexible polypropylene version. Not as durable but suitable for direct stencilling, can be washed carefully afterwards.

greatart.co.uk £3.95 ‘Rumold Duo Circle Stencils’ durable transparent yellow acrylic. Circles from 1-35mm diameter.

Specially-made templates

Sometimes it’s necessary to create a drawing template when repeated forms are needed. I posted an example of this recently in an article about making simple architectural models in corrugated cardboard. One technique when building with this material is to create repeated flat shapes which slot into each other to form 3D constructs. Below is a simple one, involving the repetition of a horizontal shape held together with repeated vertical shapes. Each has to be identical, especially re. the positions of the slots and the best way to achieve this is to cut a template first which can be traced round on the cardboard.

hexagonal building

components for hexagonal building

I cut the templates, shown in white, out of 1mm Palight foamed Pvc because this material cuts easily and the shape will last. When sizing the template I tried to compensate for the slight increase when outlining with a pencil. This meant for example that the slots in the template had to be made a touch wider.

French curves

The most regular type of curve is one which follows the circumference of a circle, having a fixed central point, and which can therefore be easily created just by using a compass. But design would be severely limited if it were confined to these. For example the curve of a spiral broadens as it progresses outwards and has no common centre. The curve of an oval or ellipse tightens at either end. Both of these forms, the spiral and the ellipse, have a pleasing regularity and their curves can be mathematically plotted if need be. But French curves are designed to take such laborious plotting out from the creation of these less ‘regular’ curves.  These tools will be familiar to most as curvy, clear plastic shapes which look like elements from a rococo pattern book. There is a standard core of three different shapes .. usually these are the only ones on offer in art shops .. which also differ a little in size, and the theory is that any curve or combination of curves can be composed with their help.

French curves

I’ve read the suggestion a number of times that being able to plot or compose curves in a digital drawing programme is making drawing tools such as these redundant. It seems to be assumed that all computer drawing techniques are bound to be easier and, typically, it misses a great deal of the point! Yes, the computer can be invaluable as a tool if .. in this case .. the outcome is known, i.e. a particular curve to fit in a particular space. But the great advantage of French curves .. and yes, working with real, physical pencil and paper! .. is that they can be used so freely and so quickly to compose with! For example I used French curves to develop the template shapes below .. wild variations on a rococo chair leg for some furniture ideas. It was so easy and quick to mess about .. to test different combinations of parts of the French curves in pencil .. before arriving at ones that looked promising!

improvised shapes using French curves

I was, however, dissatisfied with being limited by the ‘scale’ of the French curves available so I made smaller versions by reducing their outlines on the copier by 75% and 50% and cutting these shapes very carefully in Pvc. This has provided greater freedom but the disadvantage is that these are opaque, so at times it’s difficult to judge what shape is being created because part of it may be hidden while drawing. Unfortunately there’s no transparent sheet plastic I know of that can be cut as smoothly and effortlessly by hand as the foamed Pvc.

scaled down versions of French curves

Where to get and what they cost

greatart.co.uk £3.95 ‘Rumold Set of 3 French Curves’ transparent acrylic

Compasses

It is usually essential to have at least one ‘pair of compasses’ to make regular circles. As I’ve said, very small circles i.e. 20mm diameter or less, may be easier to achieve with a circle stencil or template (see above).

different compasses

But the small compass shown here at the bottom and in close-up below is a common type specially designed for small circles, although one would need practise to create a steady one less than 15mm diameter. It’s arms are fixed, but can be narrowed or widened by turning the adjustment wheel. These compasses usually take a thick lead which needs to be continually sharpened to give a clear, sharp line. The best way of doing this is with a nail-file. The more standard size and type of compass shown above it usually takes the same kind of thick lead, but I’ve modified both of these.

small fixed compass

In one I’ve substituted the lead holder for another metal point. Art or graphics shops often sell these parts as spares. The advantage of this is that a score-line can be inscribed with it instead of a pencil line and this is often enough to provide a guiding line for the scalpel blade (I write more about this and other tools to help with cutting circles in the next part on Cutting). For the other one I’ve fixed up a special type of mechanical pencil available from Rotring, which gives a thinner, consistent line with no need for sharpening. A special attachment ring is needed, which fits most compasses, and the threading on the ring is designed to take Rotring pens. I suspect though that these pencil attachments are not as available now as they used to be.

This pencil and attachment ring originally came with the bar compass, sometimes called ‘beam compass’ shown at the top of the photo. These are designed for drawing large circles, beyond the reach of standard compasses. They consist of an aluminium bar with two sliding attachments which carry the compass point and the lead holder, both of which can be fixed in position. Often the ‘kit’ comprises of two lengths of bar which can be joined in the middle to extend the reach even more. There are extension bar attachments often sold with the regular form of compass which can work well if they’re secure enough, but their reach is usually only up to a radius of 250mm (500mm diameter).

Where to get and what they cost

The quality of compasses is all in the machining of the joints, the cheaper ones possibly becoming looser in time and this is not something that one can check online. Aristo is quite a good inexpensive brand, while Staedtler and Rotring are trusted but pricier ones. The following serves as a rough price guide.

London Graphic Centre £4.10 ‘Aristo School Compass’ regular type, max. reach 400mm diameter, spare leads; £19.95 ‘Aristo Compass 7 Piece Set’ includes small and regular compass sizes and extension rod; £39.54 ‘Ecobra Beam Complete Compass 50cm’ with pencil, pen and needle attachments (the simpler kind, not the Rotring type shown above). Reach up to 980mm diameter.

Other geometry tools

Here below I am using a protractor to mark out how the steps of a spiral staircase radiate from the centre. One mistake I sometimes used to make with the protractor was placing the flat bottom edge of the plastic against the intended point of origin of the angle when it should be the centre of the small semi-circle above it.

marking up a spiral staircase

Although one might assume that one protractor must be pretty much the same as another, there are some differences in the detailing. I prefer the example below which makes it easy to read from ’0′ upwards either side .. not all are like that!

protractor

One addition I have had to make though is a few reduced size versions on the copier. Sometimes if an angle needs to be marked on a piece of work smaller than the protractor, there’s nowhere to mark on so I’ve found it helpful at times to have these smaller versions which I’ve spraymounted on Pvc.

small protractor copies

Weighing and dosing

Below is a relatively inexpensive digital kitchen scale for weighing amounts up to 5kg. For most work I’d recommend getting one which displays in increments of 1g i.e. sensitive to small amounts, so that it’s possible to mix very small amounts of resin and even record the recipes of small colour tests. The type shown below is a particularly unfussy and good-looking one from ADE Germany who seem to specialise in scales with flat safety-glass coverings. Although this weighing scale cost more than average the simple surface and cleanable glass is a bonus against spillages of resin. These scales usually take two of the small 1.5V AAA batteries and these don’t often need to be changed.

weighing pigment

A common function with these scales is that if you place a cup on the scale first and then press ‘on’ it will start reading from ’0′ without the weight of the cup. Sometimes though, I prefer to include the weight of the cup to prevent any confusion if the scale times out, which it will do if there is no activity for a few minutes.

Where to get and what they cost

They commonly measure around 16cm across and between 18-23cm in length. They can be set to either Imperial or metric measurements.

Argos £19.99 ‘Salter Glass Digital Kitchen Scale’ complete glass covering, black, touch sensor, max 5kg, graduations of 1g; £14.99 ‘Salter Stainless Steel Kitchen Scale’ circular steel weighing area flush with surface, push-button, max 5kg, graduations of 1g

Disposable plastic pipettes like these below can sometimes be found singly in craft shops, but here you may be paying far too much for them. I get these online from www.e-deala.co.uk either 1ml pipettes ( i.e. holding up to 1ml of liquid) £8.99 for 100 or 3ml pipettes £12.99 for 500. I find them most useful for dosing out very small volumes of resin and for dosing catalyst when mixing silicone rubber. They also help if you want to dose very small amounts of paint to record colour mixes by volume. Although ‘disposable’, they can be used repeatedly if they can be rinsed out straight after use.

disposable pipettes

Good model-makers looking for work

model-making

This must be the shortest post I’ve ever written .. hurrah!

I’m often asked if I can recommend good model-makers for various types of job and this usually presents me with two problems. Firstly I can never remember exactly where I’ve put people’s details and secondly it’s difficult for me to find the time to look through them and then forward the information on. It would be a great deal easier for me to be able to refer anyone who asks to an available list .. so I’m planning to compile a list somewhere on this site!

If you live in the UK, consider yourself a good model-maker and are seriously looking for work I’d appreciate it if you get in touch. You need to send me links to your work online that I can have a look at first and which clients can then refer to once the list is available. Let me know if you have any specialisms which one might not otherwise assume i.e. mouldmaking and casting,  or other drawing, design or making skills. Anyone I already know or who’s contacted me in the past about this .. apologies, but please update me!

I can only recommend people whose work I think is good or who show promise. This may not necessarily be dependent on years of experience. Times are certainly hard at the moment for anyone hoping to earn a living from model-making .. the encroachment of CGI methods in most disciplines; the economical pressure on small (and big!) commissioning companies to demand increasingly ‘more for less’ and, quite honestly, an increasing lack of foresight and time-management skills amongst the decision makers! But it’s certainly not total gloom! For example although the tide of CGI probably won’t turn for a long time, if at all .. there are ways of surviving in the water, as long as one continues to work on one’s specialisms. Look at it this way .. in years to come, once CGI has become tired and jaded through overuse a change will be desperately needed. People with practical skills will be highly prized once more because, in the intervening time, most others will no longer know how to make things!

The photo above is from David Neat Model-making: Materials and Methods Crowood 2008 and taken by Astrid Baerndal.

Basic architectural models in ‘Kraft board’

I am about to do some sessions in basic model-making for 3rd year architecture students at London South Bank University. What follows is a version of the session notes together with photos of the practical examples, and some step-by-step demonstrations of how to work with the material. This is intended as a point of reference for the students afterwards and it may repeat information given elsewhere on this site.

Models are by default ‘looked down upon’ because of their size! They can provide an instant overview, with the precision of a groundplan in three dimensions .. they flatter us with a ‘god’s eye view’, and one needs to be reminded that this viewpoint is an artificial one. For example in theatre design this is can lead to design problems .. at normal table height the designer working on the model has an Upper Circle view of the stage most of the time. But in architecture one could argue that viewpoint is less of a consideration anyway, because in this context models are never meant to be realistic simulations and it would in any case require an impossibly huge model to reproduce anything like a pedestrian’s experience of the building. For reproducing these impressions, and to preview and rehearse the organization of interiors, digital simulation may be far better suited. But even though our relationship with the card model is very removed from the one we would have with the real building, it’s also very direct .. because of its real physicality. It’s made of material .. just as we are. It needs to be handled with care because it’s vulnerable. It responds to changes of light through the window or to the shadows cast by people moving around it. It’s physicality can even be enhanced by imperfections, to a certain degree, because we’ve come to expect them in physical things.

For the first session I’ve chosen to focus on working almost entirely with ‘Kraft board’, which I feel is a very honest, unpretentious and direct material. As I’ve implied my emphasis is also on small-scale ‘massing’ models, concentrating on essential form rather than detail, serving as preliminary or idea-development models within the process. These models are more than private sketches .. they are meant to present the status of ideas so far, to communicate them to others in a clear, controlled and deliberate way. The keyword here is deliberate! Although the work may still be in progress and not yet finalised, the statements made by the model should look valued, cared for, sufficiently thought about .. in other words, deliberated. On the other hand, there should still be a feeling of ‘sketch’ .. using a fine material for this would impose a false sense of finality. So the object is to achieve a model which looks presentable and reasonably sure of itself, but also still open to discussion and without having cost a lot of time, money or effort. ‘Kraft board’ lends itself very well in this respect, because although it is structurally very strong and easy to cut cleanly, surfaces and edges retain a typically raw and recycled look. Cut edges cannot be made to look 100% smooth and detail is difficult beyond a certain level .. both of which can actually support the general aim.

architectural model

I’m assuming you probably don’t know what I mean by ‘Kraft board’. It’s unlikely that you do, because it’s the name given by the one supplier I know, Seawhite of Brighton, to a very thin form of brown, recycled cardboard which is made up of thin layers and corrugated on the inside. The outside is smooth and firm, but matt and untreated (different from the usual, thicker form of corrugated cardboard used universally, which has a very slight sheen). In the packaging industry card which is composed of one corrugated layer enclosed within a surface layer on both sides is known as single wall board and one of the thinnest is made to a 1/16th of an inch. I’m guessing this is the ‘Kraft board’ that’s available from Seawhite because this is, as close as I can measure, a little under 2mm. I had thought that the name was just a quaint variation on ‘craft’ implying that the board was for general-purpose creative uses, but it turns out that the ‘Kraft process’ is the name of an established method of wood-pulping which produces a particularly tough paper and ‘Kraft’, given by the German inventor of the process, denotes ‘strength’.

Kraft board

The main characteristics of ‘Kraft board’

In the first place it is one of the cheapest forms of card I’ve found. At University of the Arts London shops it costs £1.15 for an A1 sheet. Seawhite only normally supplies wholesale but they have a selling website www.artesaver.co.uk where a box of 25 A1 sheets will cost £24.80. Seawhite also supplies Cass Arts in London so it’s possible that it can also be found at those stores.

As I’ve said, the surface is typical for recycled card .. very matt, even slightly dusty in look, and grainy, with the odd larger speck here and there. The overall colour, a light coffee-brown, is very uniform (not mottled or patchy) and consistent from one sheet to another. There is no visible distinction between ‘front’ and ‘back’ of a sheet. Against the light the surface shows a slight roughness, like ‘sugar paper’, but surprisingly the internal corrugations aren’t visible even under glancing light. The surface picks up grease from the fingers quickly and visibly, because it’s unsealed and very absorbent. It may be a matter of opinion as to whether this matters, but if you want to keep the material as clean-looking as possible while working you’ll need to wear cotton gloves.

No exact thickness is provided by the supplier, but 10 pieces tightly pressed together come to 18.5mm thick, so for structural and scale purposes one can take the thickness to be c.1.85mm. Being hollow it is easy to cut through cleanly, though as one would expect cutting is much easier and smoother along the direction of the corrugations. Contrary to what one would expect though, the card seems to stay just as rigid in both directions so one doesn’t necessarily have to choose to cut in a particular direction for stability. It’s also very firmly bonded internally, so for example even very thin strips stay straight and intact. In fact, for something that’s basically just a hollow construction of heavy paper, ‘Kraft board’ maintains both its rigidity and coherence incredibly well!

kraft board

How to work with it

Because the surface is speckled it can be easy to lose pencil marks made for cutting, so I would recommend circling them lightly, as shown below. After cutting, these can be removed with a soft eraser.

marking out for cutting

Despite appearing soft and easy to cut with a scalpel, ‘Kraft board’ is deceptive. The paper itself is very tough and needs a sharp point to cut it cleanly. The hard fibres in it will also blunt the tip of the blade very quickly. It would be senseless, and expensive, to replace the blade that often .. but sharpening just the tip on a piece of 800-1,000 grit wet/dry paper as shown will help.

sharpening a scalpel

I always recommend patient cutting, i.e. starting with gentle passes and not trying to cut through in one go, but this is particularly important with ‘Kraft board’ otherwise the edge will compress or parts of the paper might tear. For more advice on marking out and cutting generally, see ‘Main construction’ in Methods /- Making realistic models.

The following sequence of photos shows the steps, techniques and additional tools recommended for making a simple ‘box’ form, i.e. a building block comprising roof and walls. Although this is the simplest possible exercise, it illustrates many of the basics of effective construction with this material. The first advice is that, since the model is mostly viewed from above, roofs assume more significance so the overall look will be cleaner if these are complete and without seams (i.e. walls stuck underneath them rather than around). I’ve found that generally the cleaner way to build this type of model is the opposite of real construction .. building from the top downwards.

simple blocks

I’d also recommend that the walls should be cut with the corrugation running from top to bottom, so that the corner seams are less obtrusive. The distinctive ‘zigzag’ patterned edge that occurs when cutting in the other direction cannot be completely avoided in the model .. and can sometimes be used to good effect! .. but it can at least be controlled with a little thought.

In the photo below, the top piece has been cut together with a much longer piece for the sides, long enough for all four. This ensures that all four walls will be exactly the same height and that the box will stand well when reversed. The next ‘trick’ is to measure from the cut roof and divide up the strip only as-and-when each piece is needed, rather than measuring/cutting all pieces out beforehand. This avoids many of the slight discrepancies that are bound to occur.

longer strip for sides

I use solid metal blocks as supports for gluing. These ensure that the wall, shown below, can be positioned correctly on the edge and maintains a right-angle. Steel blocks like these are not available in D.I.Y stores but can be bought online at, for example, www.metalmaniauk.com The best glue to use when working with any card is Pva wood-glue because it’s strong, clean and allows for some repositioning. But better still are good quality wood-glues from Evo-Stik or Loctite rather than the weaker ‘school’ Pva. These make the work easier because they grab and set more quickly.

DSC06724_sm

measuring insert

Above, I’ve glued the two parallel walls first and waited a little for them to become firmer. Then I’m marking the length of wall which needs to be cut and inserted between them. Usually this results in the best fit. Below, the glue needs to be applied to this piece rather than the insert so that the glue isn’t squeezed out onto the surface when it’s pushed into place. Pva glue need only be used very sparingly with this type of card.

applying wood glue

Below, once the piece is inserted the work can be turned around and a flat surface used to level the wall into position. A good Pva glue will hold absorbent cardboard firmly enough for handling after a few minutes though it will take longer for the glue to fully harden.

using work surface

Essential and recommended tools

I’ve written more about these tools in other articles such as ‘Main construction’ which can be found in the Methods /- Making realistic models section, but I’ll repeat the main points here.

Scale ruler There are two types in common use for metric measurements .. flat, 2-sided and triangular, 3-sided. The flat ones may look more elegant and sophisticated, but my preference is for the triangular because they are often clearer, with bolder calibration. They are also a little harder to lose amongst the clutter of a work table. The one shown in the foreground below is actually more for interior or theatre design, the smallest scale included being 1:125. Architects’ scale rulers have a greater range, usually down to 1:2500. Because of this the scales are paired on each of the six edges i.e. 1:1250 with 1:2500 etc. If you want to read more on working with scale rulers see the article ‘Working in scale’ in the Methods section.

scale rulers

Mechanical pencil It is essential to use one of these, shown in the photos above, to make a consistent, fine line when marking up for cutting etc. But this doesn’t need to be an expensive one .. the cut-price ones from any supermarket will do almost as well. I personally prefer to use a special type though which takes a 0.3mm ‘H’ lead, finer and harder than the usual ones, which gives better accuracy.

Scalpel or fine cutting knife I prefer a surgical scalpel, far left below, because it cuts better, is easier to control, and the blades can be more easily re-sharpened. These are made by Swann-Morton, the best handle size is No.3 and the best general-purpose blades to use are ’10A’. The more common type of fine cutting knife to the far right has a round barrel which is more difficult to keep steady and the blade wobbles more because it is less supported. There is one drawback in choosing the scalpel type, and this has started happening only in recent years. For some reason, perhaps because of cheaper manufacture, blades are almost impossible to slide onto new scalpel handles without the help of pliers. One should be able to do this comfortably by hand, but the fit is just too tight.

fine cutting knives

Small try square The one in machined steel shown below is more properly termed an ‘engineer’s try square’ but other, usually 25-30cm ones can be found for general D.I.Y or woodwork. It’s possible to survive without one, but being able to check and mark out right-angles, especially repeated ones, like this can safe a vast amount of time.

try square

Cutting mat The size depends on the size of models you are likely to make but usually an A2 cutting mat is more than enough. It’s best to opt for the cheapest deal you can find if you need to save money because the ‘quality’ doesn’t really make any difference. What matters more is that it’s kept clean .. put aside while painting or especially supergluing because these will quickly make the surface less effective. Whichever brand or source, I would recommend one with a prominent centimetre grid as shown below, because this can help a lot when cutting parallels.

masking tape on metal ruler

Flat metal ruler A metal straight-edge is essential for cutting against and in my experience the best for this purpose are the cheaper, flat steel ones. These are normally available in four lengths .. 15cm, 30cm, 60cm and 1 metre. As with the cutting mat it may be difficult to determine which size will be needed most, but I would recommend that if you opt for a 60cm you really have to get an additional 15cm because it’s a pain having to manoeuvre the long ruler around for small cutting. A strip of masking tape on the back of the ruler, shown above, is essential to make it grip better.

The advantages of making ‘slotted’ forms

The special rigidity of ‘Kraft board’ makes it an ideal material for trying slotted, interlocking forms. This was how I put together the structure shown in the first photo and below, also in close-up.

slotted construction

slotted form close-up

It is just a series of identical floor shapes and identical upright supports with slots cut so that they can interlock, and dependent on the stability this might not even need to be glued. It is by far the easiest way of achieving multiple storeys and uprights which are all reasonably aligned and straight! To achieve identical cut-outs I made Pvc templates first, around which each form is traced in pencil on the cardboard. I had to make the slots on the template a little wider to compensate for the extra width of the pencil line.

slotted storeys with template

This might be a little clearer from the following photos showing a similar, earlier construction.

components for hexagonal building

hexagonal building

It is common practice to indicate slopes or variations of the terrain in layers corresponding to the height levels on a contour map, as shown in some of the photos above. Once again this is easier from the top downwards, cutting out the smallest shapes first and using these as templates for the larger. I prefer to fix these together using evenly spaced pieces of strong double-sided tape, but Pva glue can also be used. This should be applied in small, fairly widely spaced spots (spreading too much glue will cause the cardboard to warp) and ideally the layers should be weighted down while gluing. UHU can also be used for this in a similar way but this needs to be done quickly before any of the glue spots dry out too much.

While working on these landscape layers I looked at another interesting way of creating a smooth gradient by constructing the building blocks first, cutting holes in the card and positioning this around them at an angle, as shown in the photos below. With a relatively simple model this would be a lot easier than sloping the bases of the buildings.

buildings inserted

angled for slope

‘Models as art-form’: the constructed images of Graeme Webb

In recent years there has been a significant increase in the number of visual artists who are either experimenting with the model form or wholeheartedly embracing it as a means of expression. I have attempted to track this since the early ‘noughties’, but up to now I haven’t shared much of my research, perhaps because I’m still not sure about what I’m dealing with. But I feel that the time is right again now! .. over the next year I want to take stock of this here and hopefully reach a better understanding of the rich variety of work produced.

I can think of no better place to start an appreciation of this form of expression than the work of a good friend Graeme Webb! Graeme is in equal measure a painstaking and inventive model-maker on the one hand and an experienced photographer on the other, so it seems an almost pre-destined form of ‘natural selection’ that he will combine them so well in this form. He is also a very British artist! I’m not implying that this is a mark of distinction in itself! .. just that for me it’s closer to home. We Brits don’t have the monopoly in being subtle/understated, nor are we the only ones who can be quirky/original .. but we’re pretty good at managing both at the same time! In my forward to his e-book Bleak House and Other Places I refer to Graeme’s place amongst those precious ‘guardians of dreams’ who are content to reference the irrational, strangely beautiful or uncanny without feeling the need to explain, dissect or confine. I am reproducing parts of that forward here, within quotation marks.

Untitled, 2011

Untitled, 2011

‘But in his manner of gently pointing to these dreams Graeme doesn’t seek to disguise where they come from. Books on child psychology often talk of ‘the imaginative landscape of the child’ and if they ever needed tangible illustrations of this phrase they couldn’t do better than Graeme’s. It’s not enough to say that Graeme’s work is firmly rooted in his childhood experiences; in some sense it is Graeme working as the child
he was (or, I’m sure he’d say, .. still is) but using the depictive skills he has amassed over many adult years. The energy, the blinkered concentration .. the obsession! .. that he brings to his work are youthful! The masterly manipulation of materials and photographic effects, the composition .. and equally the wry, understated humour! .. are decidedly senior.’

Landscape_4, 2011

Landscape_4, 2011

‘Children aren’t so bothered by differences in scale when playing with their toys, neither are they too choosy about what can serve as a stage .. a piano keyboard can instantly become a street, a plumbing pipe becomes a cliffwalk .. and Graeme captures both the ingenuousness and the delight in this. But the state of abandonment and ruination coupled with the fading family photos remind us that this is a child who has irreversibly
matured, looking back on times long past.’

Headz_set view_7, 2012

Headz_set view_7, 2012

Bleak House_tree on table

Bleak House_tree on table, 2010

‘What is it that is so appealing about the decay and dereliction of interiors and buildings? Of course there’s the aesthetic appeal, for those who are tuned to it; it softens or shatters hard lines, it gives more textural and colour variance. Then there’s the conceptual aspect; it signifies the indomitable will of nature which we can either fear or be reassured by according to inclination. We can either read it as nature caring nothing for us and our things, or as nature taking us motherly back ‘into the fold’. But these are grown-up and cultivated responses. Deeper down, decay and dereliction are enticingly taboo; we were told to avoid them as children. These things break the rules merely by existing, and we break the rules by going near them. Also in that deeper place lurks the childhood apprehension that those things we rely upon to be stable and permanent, such as the family sitting-room, may be subject to the same changes.’

Headz_set3_The Garden (2), 2012

Headz_set3_The Garden (2), 2012

The Pumpkin Brothers (2)

The Pumpkin Brothers (2), 2010

Bleak House_window view

Bleak House_window view, 2010

As a rule Graeme’s photos are almost totally created ‘in camera’ .. using digital only in so far as a traditional photographer would have employed certain ‘post-production’ methods in the darkroom, to adjust colour and contrast for example. Though figures or vehicles are found, everything is made on the table-top using practical/physical materials .. cardboard, foamboard, texture and paint media, plant material and flocking. Lighting effects are achieved through the painstaking use of torches with gels attached, smoke and projection .. exposures are long and hundreds of tests are taken before the right one is found.

Headz_set2_view_2, 2012

Headz_set2_view2, 2012

‘The French symbolist painter Odilon Redon spoke of the power harnessed in using the language of the ‘visible in the service of the invisible’. Graeme does this in many refined ways .. a pinpoint attention to significant details here and there; a convincingly ‘realspace’ concoction of light and atmosphere; a careful manipulation of viewpoint and focus. All of these transport us away from the lichen, cardboard and paint, away from the table-top .. the images become convincingly other ‘places’. But on the other hand, he also plays with the reverse, acknowledging the contrary language of the ‘invisible’ .. purposely preserving something of the hand-made, the improvised, the fortuitous or the downright arbitrary; collaging different scales; subverting the usual distinctions between insides and outsides. All this calls for a fine sense of balance.’

Alone on a Hill

Alone on a Hill, 2010

I believe that Graeme consistently achieves that balance .. all the more surprising considering a prolific output within the relatively short space of the last few years! Yes, I may be biased, but for me Graeme’s work counts amongst the most honest, evocative and accomplished in this form .. and nothing in his work so far has caused me to regret any bias!

At present Graeme is transferring his work from his older site to a newer one on WordPress http://arcimboldistudios.org/ This will take a while but current work, including a new collaborative project A Guide to the Birds of the British Isles can be seen there. He also has a facebook page www.facebook.com/ArcimboldiStudios which links to both the new WordPress site and Graeme’s photostream on flickr http://www.flickr.com/photos/arcimboldi/ His new iBook Otherworldly for iPad is available from the iTunes Store.

‘Model-making Basics’ – painting

This is the final of five outline accounts dealing with what I consider to be the five defining areas of model-making work; main construction, fine construction, modelling/shaping, creating surfaces and painting. I’ve written these overviews in preparation for teaching sessions at RADA ( Royal Academy of Dramatic Art ) in London. So they’re tuned towards the specialities of theatre design model work, but most of the points will be relevant in general terms to model work in other disciplines. I’ve started with the general ‘themes’ or requirements of the subject, followed by more specific and practical guidance on the materials and methods which can be used.

I always start by thinking, at least for a brief moment, that there’s not much that I can say about painting! I think this is because I feel that painting is a highly personal thing .. everyone will have their own ways of going about it, and whatever one says about it each person will learn best from their own experiences. I think another reason is that although I’ve done a lot of painting, of various kinds over many years, I still feel like an outsider. Painting is still very much a ‘trial and error’ experience for me. Maybe that’s exactly what it should be .. in order to keep the experience alive and to stay alert!

painting materials for model-making

In fact there’s an awful lot that can be said about painting in this context, if only when one considers the variety of materials one can use as paints .. a wide range of acrylics (‘heavy body’, ‘light body’, liquid or ink-like), gouache, watercolour, tempera or ‘poster’ paint, inks and stains, polishes, enamel paints, artists’ oil paints, spraypaints (DIY, graphic art or graffiti sprays), coloured pencils and pastels, wax-based rubbing paints .. and so on!

I like the term ‘model friendly’! I picked it up from somewhere along the way and it’s usually the first thing that comes to mind when I have to focus on the subject of painting models. So what is ‘model friendly’ painting? An ideal paint for model-making needs to be opaque enough to cover properly without streaking, but at the same time thin enough to do it without clogging fine detail; it needs to mix well, be easily thinned and easily removable from brushes; it should be inexpensive and readily available in a good range of colours; it needs to dry quickly and it helps if it’s self-sealing (so that it can be quickly worked over once touch-dry without dissolving); it also needs to be adhesive enough to stay on a variety of materials, including if possible plastic and metal, and strong enough once dry for light handling. My preference is also for a paint which is matt by default (if a glossy surface is needed this can be better achieved by varnishing a matt surface rather than having to use a separate gloss paint. This gives more control over the results). It also helps a lot if additives are available to extend its properties further i.e. to dilute it heavily without affecting its adhesion so that it can be used as a transparent glaze, or to slow the drying time so that it can be pushed around or wiped off, as oil paint can.

If such a single paint existed it would inspire feelings of much more than ‘friendship’ towards it .. unfortunately it doesn’t exist! But one can get all these things from using a combination of just a few. Acrylic paint comes close, but there are shortcomings and it depends a lot on the type, as I will explain later. The same applies to oil-based enamel paint (more properly called ‘cold enamel’, familiar as the small tinlets from Humbrol or Revell) .. this is an extremely ‘model friendly’ paint in many respects, but lacks versatility. What is not so often considered though is combining the two .. I don’t mean literally mixing, because they won’t, but using them over each other. Coloured pencil, pastel crayon, shoe polish, metallic waxes etc. can also be applied over either of these paints to modify the effect. Many of these combinations would not be open to a serious artist concerned with permanence, but are nevertheless sufficiently durable and lightfast in the shorter term.

GENERAL APPROACH

Observation and visual research

I won’t repeat what I’ve already said about the importance of starting with the right visual information and the need for interrogating the true ‘look’ of something before representing it .. just see the previous post on this subject.

One shouldn’t have to argue that it’s the duty of all who are involved in the creation of images of the world to have a good understanding of its true colours, regardless of how these might then be manipulated to support an idea. One should be fully aware for example that light skin is not simply ‘pink’; that concrete is not really ‘grey’, and that tree trunks are very rarely ‘brown’! Our sensitivity to these things is really not helped by our common language! Quite apart from such brutal distortions as describing people in terms of ‘white’ or ‘black’, we don’t have much of a vocabulary when it comes to the rest of the colour spectrum .. red, yellow, blue, green, orange, pink, brown and grey, that’s often about it for most people! I think this may be one of the reasons why children invariably start by painting tree-trunks brown and often continue to do so in later life .. when the child asks what colour they are, ‘brown’ is just the closest from a limited range of words to describe it.

Most often reaching an understanding of true colour is not simply a case of identifying just one but discovering the interplay of many. A brick wall for example, even the blandest of modern ones, is a subtle pattern of many related colours .. and the trick is to reflect this in a balanced and economical way. In the previous post on Creating surfaces I talk about identifying the essentials of a look or a natural pattern .. seeing the visual recipe .. and conveying that in the model. At such a small scale it’s usually not possible to include everything that the real-life surface contains and it shouldn’t anyway because it is after all an artifice! The small scale forces the designer to concentrate on the few most relevant essentials and the model is the best vehicle for testing what will work.

Planning for painting

Don’t leave painting to the last! This may seem like a funny thing to say, because one would assume that the other processes involved in the making of something all have to come first! Of course they do, when we’re talking about individual elements, but a theatre design model may be composed of hundreds of different elements nearing completion at different times. It may seem logical, even sensible, to complete all the preceding steps on all of these until there’s nothing left but to concentrate on the painting .. but I think this could be a big mistake! There’s an advantage to finishing some of these elements ahead of time just to give yourself an idea of the final look .. whether that turns out how you thought, or whether it prompts a rethink. Also, unless final painting is mundanely straightforward, it is difficult to predict how long it will take to get the desired effect so the sooner one can start investigating the better. A set design is a composition which is no less visually involved or precisely balanced than a painting! I don’t know of any painter who would construct all the elements of a painting in precise detail as a complete drawing and then leave all the colouring-in to last! One needs to preview a great deal as one goes along, for example how colours and surface qualities change forms and react with each other. Often starting the painting process sooner alleviates stress .. for example when discovering that the material chosen for surfacing actually needs very little painting or that the surface texture created does most of the painting work on its own when it’s dry-brushed.

keeping separate for painting

While elements of the model are being made it’s necessary to keep a constant question going in one’s mind as to how they’re going to be surfaced .. whether they’ll be given just a flat colour which can be easily applied once assembled, or whether the different treatment of parts means that it’s better to keep them separate till the last, as above.

However, even if you try hard to paint as you go, it’s often a ‘sod’s law’ inevitability that much of the final painting is done in a rush, because most of the preceding stages take longer than planned, and this is often made worse by not even ‘kitting out’ for painting properly beforehand. By this I mean a number of common sense things .. making sure that reference images are organized and visible; making sure that you have all the paints, additives, brushes and other tools you are likely to need including any specials such as stains or metallics; having scraps of the materials you have used to make tests on; uncluttering the workspace, making sure that it is clean and comfortable; making sure that there is a continuity of reliable, neutral light well into the night!

The composition of paint

It’s very worthwhile knowing at least a little about what goes into a paint! This not only helps with how to use them but also how to change or extend them. Basically paint is composed of .. a mineral or chemical pigment which provides the colour and is usually very finely ground; a solvent such as water, acetone or turpentine which carries the pigment particles and which, upon evaporating, causes the paint to dry; and a binder, in other words a glue, which makes the paint stick to a surface and then hardens to make it durable.

The pigment is not ‘dissolved’ in the solvent but suspended in the form of fine particles and these will differ in shape according to the different minerals or chemicals used. The opacity of a paint, i.e. how well it will cover without lighter streaks showing through, is as much dependent on the shape of those pigment particles as anything else. For example jagged particles are likely to clump together whereas smoother particles will stay apart. For this reason certain colours will usually cover more evenly than others, regardless of the type of paint. Earth colours for example always cover well, whereas some reds or blues are invariably streaky. To compensate for this and to even out the differences a fourth ingredient is commonly present in paints .. a filler. This is also a finely ground powder, but one which is itself colourless and chemically inert. Chalk is commonly used as a filler in gouache, alumina hydrate is another often added to acrylics, and others include marble dust, kaolin, silica and talc. Some more modern, synthesized pigments such as pthalocyanine are so intense that fillers are essential to tone them down and make them ‘palatable’. Gouache is a form of watercolour with a high proportion of filler added to make it especially opaque. But on the other hand fillers are most often added just to extend the paint volume and make it cheaper to produce. It stands to reason that cheaper paints will have an excess of cheap filler, resulting in colours that are rather dulled. This may not be so obvious at first judging by the colour squeezed out from the tube, but it may not keep that colour on drying and the lack of pigment intensity can become very apparent when mixing two of these colours together!

In many paints the solvent which carries the pigment is the same as the solvent in the binder .. for example in most regular, brush-on acrylics it is water. The paint dries and hardens as both evaporate. So why does the pigment need to be ‘wetted’ with the solvent separately? .. can’t it just be added to the binder in one go? If you’ve ever tried to mix your own paint, for example by adding Pva glue to powder pigment, you’ll know that it’s much easier to integrate the dry pigment with the glue if the pigment is made into a wet paste first. The water serves as a bridge between the two and helps prevent pigment particles from clumping together.

The binder, which is essential to provide both adhesion, sealing and eventual hardening, is what principally differentiates paints from each other. The binder in most regular acrylic paints is an acrylic polymer (it doesn’t mater so much here what is meant by that, but if you want to know find the entry in my Lexicon above). In artist’s oil paints the binder is commonly linseed oil; in gouache and some watercolours it is traditionally a very small amount of gum arabic, and traditional tempera paints were commonly made using egg yolk, sometimes animal glue or honey. It is mainly the binder .. or rather the extent to which the binder is modified .. which determines whether a paint will dry matt, silky or ‘eggshell’, or glossy. But it can also depend on the granular size of the solid ingredients, since even minutely rougher surfaces will appear more matt because the light reflected from them is broken up in various directions. Less finely ground pigments may make the paint more matt or a higher proportion of filler in a paint will ‘absorb’ much of the shine in this way (though at the same time diminishing the colour intensity). Sometimes a small proportion of wax is added to paints as a matting agent.

Knowing these things means that you might, to a certain extent, be able to change the paints you have .. perhaps by adding more glue to make the paint stick better or dry harder, or adding more filler i.e. chalk dust or talc, to make it more opaque or matt. Some additions may react with certain ingredients of the paint and make it unusable i.e. making it too thick or preventing it from hardening .. but it’s worth a try and you might even improve it!

Colours

Whatever paints you use, it’s important to be able to get any colour you might want .. its vibrancy, hue, lightness or shade .. as easily as possible. Control over colour begins with having at least a good basic collection of essential colours plus white .. and let’s also include black for the moment for convenience .. and I deal with choosing colours later in this section. But it also depends on being familiar with other individual properties of the paints you have. For example there will be quite a variation in the properties of different colours within the same range from the same manufacturer .. some will be more opaque than others; some will thin more evenly; the pigment in some will be more concentrated and dominant than others; some (especially in the case of acrylic) will dry glossier than others! So getting the green you want is not necessarily just a case of mixing the right yellow with the right blue for example. I only started doing the following once I’d amassed too many paints to choose from at a glance, but I wish I’d started much earlier .. making paint swatches!  I originally started making them purely because one only gets a generalised idea of the colour from its packaging, but then found that this could tell me a lot more besides about the behaviour of each paint compared to another.

paint swatches

I’ve made this kind of test, shown above, with every paint and every colour I have .. brushing each in its strongest undiluted form for about a third of the way down but then thinning it carefully to get a fade to almost nothing. It’s important not to labour getting an even fade but to go with what the paint does naturally so that if the paint is, for example, difficult to graduate the swatch will reflect this. I’ve used pieces of oil-painting paper to paint on, because this type of primed surface is a good ‘average’ .. neither too absorbent, nor too resistant .. and it’s very pleasant to paint on, whether in oil-based, spirit-based or water-based paints. These give me an instant visual record of how well the paint covers, how the consistency changes when diluted and how matt it will dry. Some colours will even change in hue when thinned and this is important to know before using them. For example there are rich reds which appear fairly neutral when seen at their full strength but which reveal a strong bluish bias when thinned or mixed with white (more on colour undertones later). Or there are even colours composed of more than one pigment where these start to separate when thinned such as the chocolate brown below. This contained some strong pthalo green which is appearing towards the bottom of the sample.

pigment separation

Nothing replaces having to experiment with colour mixes on-the-spot i.e. when you need them, but looking through these swatches has always helped me to define the colour I want and make better choices as to how to achieve it. But it’s also a fact that having to mix colours from scratch each time one comes to painting is tedious! .. and we all have favourites that we use time after time. I mix up large amounts of favourite colours when I’m in that kind of mood and (since I prefer using acrylics which are more liquid) fill flip-top dropper bottles of the type shown below. This is the most convenient and economical way to dose out paint, in very small amounts if need be. Often I’ll re-use the old bottles from bought paint but £shops also sell ‘travelling bags’ containing bottles of shampoo, shower gel etc .. the cheapest paint bottles around at 4-5 for £1!

best dispensers for paint

We’re probably all familiar with the basic theory .. that one should be able to get any colour hue one wants using just the three primaries, red, yellow and blue, with the addition of white to lighten the tint (hue by the way means colour, tint means the colour mixed with white and shade is the colour mixed with black). You may also have picked up the advice that one shouldn’t need a black .. that a sufficiently ‘black looking’ colour can be made from a combination of the three primaries. Anyone who’s tried to find those three magically pure, neutral and equally strong primaries amongst the range of existent paints will know .. it just doesn’t work like that in practice! There are vibrant reds that feel closer to orange, while others will feel closer to purple. The same is true of blues .. either they’re too dark to judge in the shop, or they feel closer to either purple on the one side or green on the other. I think a lot of people think that they’re at least on safe and neutral ground in choosing a strong yellow .. but even here there’s likely to be a subtle bias towards either orange or green.

You might ask .. do these subtle biases matter that much? If we’re going to mix colours together, can’t we eliminate the biases anyway? The fact is .. no we can’t, if we’ve just got those three paint colours to work with. Imagine for example that you’ve chosen a red which was the most vibrant you could find, but it’s just a tiny bit on the purple side .. in other words towards blue. You want more of a pillar-box red but just as vibrant, so you add some yellow to it. The resulting colour is duller than you expected it to be. At that point you might remember another piece of the theory .. that complementary colours (those opposite each other on the virtual colour wheel, see below) actually cancel each other out, producing a form of grey. This is what has happened between your yellow and the trace of blue in your red .. and there’s nothing you can do about it! Actually the opposite of blue is, strictly speaking, orange but a warm yellow can be close enough to it. It doesn’t even help if the yellow you’ve got is one that tends towards green instead .. in this case the green and the red being opposites will also dull each other! It’s not usually possible to make colours brighter (i.e. not just lighter but stronger in chroma, to use another accepted term) by mixing them and most often it’s the opposite. If for example you want to make the brightest possible green from blue and yellow you have to combine a blue which already has a green bias with a yellow which also has a green bias. If you then want to lighten it without losing colour brightness or ‘chroma’ you add more yellow, or if you want to lighten it and tone down the brightness you add white.

colour wheel

Then there’s the theory that a good black can be obtained from a combination of primaries. If you choose those three primaries according to their visible brightness then this probably isn’t going to happen .. you may get a form of dark grey at the most! To obtain a convincing black you need quite darkly biased versions of those primaries .. a rich Prussian blue and a dark magenta for example.

The simple answer seems to be .. if you’re not so concerned about vibrancy of colour, and 100% control in achieving every nuance of colour possible, then you could well be satisfied with the three closest possible primaries, plus white .. and yes, why not, including a black just to make life easier! Many paint manufacturer’s websites contain advice on the best three colours to choose if you have to, such as the following from Winsor & Newton:

http://www.winsornewton.com/resource-centre/hints-tips-and-techniques/colour-mixing/practical-applications-of-colour-theory/

Here the company recommends for example using it’s ‘lemon yellow’, ‘Winsor blue’ and ‘Permanent rose’ when working with its Galeria acrylic range because these it says are closest to the printing process colours .. yellow, cyan and magenta.

If on the other hand you’d like more control over colour, you will need at least two versions of each primary, plus a few others besides according to personal preferences. My own personal preferences are as follows:

Red cadmium red medium (yellow bias) and quinacridone red or permanent alizarin crimson (blue bias)

Blue pthalo blue (green bias) and ultramarine (red bias)

Yellow cadmium yellow medium (red bias) and Hansa yellow or lemon yellow (green bias)

I also rely fairly heavily on having others which may not be strictly necessary but which I’ve got used to using anyway .. pthalo green (a very strong, vibrant green with a blue tinge), yellow ochre (an essential basis for naturalism), raw umber (a rich dirt colour), red oxide (or a rich terracotta i.e. a convincing brick-red), Prussian blue (mainly for making black or for darkening greens).

Here I’ve tried to use just universal or accepted colour names in this list .. rather than others like the ‘Winsor blue’ for example because the chances are that they will be fairly similar amongst different manufacturers. But unfortunately there’s no 100% guarantee, even when the standardised pigment identification CII (Colour Index International) number is the same! What all this boils down to really is how I began this section .. for the most reliable control over colour you need to make swatches of the colours you have, identify which are strong pigments and which are weak, practise mixing and build on your own personal experience.

Using ‘natural’ accident

It’s very difficult to create a natural, convincingly random effect by deliberate means! Strictly speaking it’s impossible! .. and in any case one could argue that when the eye of the designer is involved it’s not going to be truly random anyway because there will be a fairly strong element of selection and personal preference, and the urge towards aesthetic balance that true nature doesn’t always care about. However, it’s often necessary to create the semblance of randomness, and for this it’s usually better to discard the brush, using other things such as crumpled tissues or natural sponges to dab paint on .. anything in fact which defies complete control. Making textures do the painting .. i.e. stippling polyfilla to make a rough surface and either dry-brushing or thin-washing over it to bring that texture out .. is good in this respect because there are always some surprises, elements that weren’t planned. I like creating paint effects by spraying though something else such as scattered granules or torn netting (see Creative spraying further on) because it increases the element of chance.

Waiting for paint to dry

I’ve included this as a ‘general’ point because I think there’s a lot of confusion about how long different paints need to dry and harden thoroughly. Many paints become touch-dry very quickly but this doesn’t necessarily mean that they are ready for anything! For example a very thin coat of acrylic paint may be dry enough to over-paint safely in under a minute but the complete hardening of the paint to attain its full strength and adhesion to the surface will take days! In fact, acrylic paint can be particularly misleading because thicker coats will quickly develop a skin (especially annoying when they are still on the mixing palette) while underneath the paint can remain soft and damageable for weeks! The same goes for the matt enamel paints featured later .. they can also be dry to the touch in a matter of minutes but will remain very susceptible to handling until they’ve had a full 24 hours to dry completely. These enamels dry differently from acrylics .. they dry from within and do not form a skin, hence the fact that although initial touch-drying can take longer, complete drying is generally quicker.

PRACTICAL GUIDANCE

Priming surfaces

We’ve looked at the importance of this as a safeguard against warping in the previous post on Creating surfaces. But that’s not the only reason why priming (i.e. painting or spraying an undercoat) is important. Acrylic paint is often favoured because it will take to a variety of surfaces and dry properly on them without those surfaces needing any special preparation. This is generally true .. but there are times when even acrylic needs some assistance with covering evenly. Some acrylics (if they have a strong binder) don’t necessarily need an absorbent surface and will even stay on plastic, but most often the smoother and less absorbent the surface the ‘streakier’ the brushstrokes will be. The paint covers but it’s almost impossible to get it to cover evenly. This is partly down to the individual properties of the paint .. there are pigments which are more opaque than others and there are paints which are designed to be more opaque, as I’ve said. But even coverage is also dependant on the structure of the surface being painted. A good example is provided by canvas which, even today, is still largely unquestioned as the best possible painting surface. It’s texture traps paint and the regular weave tends to portion it evenly. In painterly terms this is often referred to as the tooth of the surface, and the oil-painting paper I use for colour swatches has a regularised tooth. Gesso which is for priming canvas or underpainting in white has a slightly rough tooth, though much less visible, which helps to anchor the paint more evenly.

Although paint will take better to absorbent surfaces it also sometimes makes sense to make those surfaces somewhat less absorbent, another reason for priming. This means that paint can be more easily moved around or sometimes even fully removed rather than immediately soaking into the surface (see later Staining, tinting and varnishing and the use of semi-absorbent oil paper). Some oil-based paints fail to dry properly if the ground is too absorbent because it soaks up the oil too quickly, leaving the pigment as a powder on the surface.

Working with acrylic paints

Acrylic paints seem to be the ‘default’ choice of theatre designers for their models .. tube acrylic paints, that is .. particularly amongst students or beginners. When I go to teach 1st-year theatre design students I see boxes of them everywhere and, understandably, these are often the ‘discount’ or cheaper kind. I’m afraid to say that I personally don’t get on very well with tube acrylic paints and from the look of many of the results .. neither do they! I find it much too thick, and difficult to thin down evenly; I’m happy for it to dry fairly quickly on the piece I’m painting but annoyed that it does the same on the mixing palette .. but more annoying is the silkiness or even glossiness that remains after drying which is usually inappropriate to what I’m painting!

Some types of acrylic paint are much more ‘model friendly’ than others. For example I like painting with the bottle acrylics found in many craft/hobby shops because these are generally thinner, more opaque, more matt, longer lasting and much easier to dose out. The ‘Americana’ or the ‘Crafters’ range from DecoArt, below, are the best I’ve found in these respects. They must have a good binder, because generally I’ve found they will fix well onto most things, even foamed Pvc if it’s lightly sanded, and when dry they are sufficiently hard-wearing.

DecoArt bottle acrylics

Apart from their good performance, I like their handy, tight-sealing, flip-top style which keeps them remarkably well and allows me to dose single droplets if needed! This is a big plus in terms of comfort! On the downside, the colour range is certainly not as good as most other ‘artist’s’ acrylics and the shops which sell them don’t tend to stock the full range or keep it stocked anyway. I wouldn’t use them if I wanted complete colour freedom or vibrancy .. but I often rely on them for my usual ‘naturalism’ palette. They’re not expensive .. the common price for a while now seems to be £1.99 for 60ml.

There are other acrylic brands in similar bottles, and some of these work just as well but some do not. The ‘Inscribe’ range is good, as is the ‘Folkart’ and ‘Anita’s’ .. I haven’t tried them all! The £shop-like chain ‘The Works’ stocks some useful things from the ‘Royal & Langnickel’ brand including their bottled acrylic paints. Some of these may be usable, but the darker colours I’ve tried were very streaky (i.e. too transparent) and they dried almost gloss!

An excellent form of acrylic paint in just about all the respects I’ve mentioned is the SuperSaturated scenic paint from Rosco. This is concentrated, and pigment strengths are fairly well-balanced. 1 litre bought will make 2 litres of strong, opaque paint and it mixes readily with water. It contains a very strong binder and it’s claimed that this is strong enough to stay put on plastics and metals (though in practice these surfaces need to be roughened at least). Good coverage can be achieved thinly and it dries very nicely matt! Unfortunately it’s anything but cheap! It’s normally only available in the 1 litre pots and these can cost between £12 and £25 each. There’s a tester box available which is very useful, shown below but this costs around £50. However, if you’re on friendly terms with a scenic workshop that uses these paints you won’t regret filling some sample bottles!

Rosco SuperSaturated range

Acrylic owes a lot of its popularity to the fact that it dries so quickly, meaning that relatively little time is wasted between coats. But this also means that acrylic can’t be manipulated, especially blended, with the same ease as oil paint which remains workable for a great deal longer. It also means that it’s difficult to use textured applicators such as sponges to distribute the paint before it dries on them. For these reasons manufacturers of artists’ acrylics sell what they call retarders which can be added to the paint to slow the drying time. The retarder medium also becomes a perfect vehicle for making the paint more transparent, as a form of glaze, if enough of it is used. I use the retarder for acrylics from Winsor & Newton, which seems to work with all types of acrylic I’ve tried. Below I’ve mixed quite a high proportion of retarder to paint  and used natural sponges, crumpled tissue, newspaper or rags to distribute it over paper. It remained workable .. i.e. movable or removable .. for about 15 mins.

using a paint retarder

Working with gouache

I see almost as many boxes labelled ‘gouache’ in theatre design studios. Gouache is basically a modified form of watercolour, with a filler such as chalk or talc added to make it more opaque (hence it covers evenly) and usually a little glycerine to help it brush or ‘flow’ better. Like watercolour it contains only the minimal amount of binder needed to hold it together because after all, it’s meant to be used on a properly absorbent surface such as paper and it’s not meant to be touched afterwards. It can’t be over-painted easily without re-dissolving what’s underneath .. but this does mean that some nice blending is possible. It’s also agreeably matt! Another difference to acrylic is that whereas light gouache dries a little darker, dark will dry a little lighter.

mixing Pva glue with gouache

Because it has very little binder in it, it is neither sticky nor durable. So if for example you paint a modelled figure with it, it may have just enough cohesion to stay on the surface and dry there but it will fairly readily come off. However, gouache can be very easily modified just by adding a little water-based glue. I usually mix in roughly the same amount of Pva wood glue to gouache on the palette. I’ve had good results with this .. even taking on, and staying on, plastic. If you’re careful with the proportion of Pva used it shouldn’t change the matt quality of the paint too much, but it will change the covering properties i.e. it will make it more transparent and therefore a little streaky.

Working with enamel paints

The term ‘enamel’, when applied generally to a paint, is supposed to denote that it will be particularly hard-wearing, but it should not be confused with the ‘enamel’ finish given to metalware which is much harder because it is fused on using heat. ‘Cold enamel’ paints are commonly available in gloss finish but can also be found in ‘satin’ finish or matt. They are also commonly oil or spirit-based rather than water-based. Generally the matt versions are suitable for painting straight onto absorbent surfaces such as regular paper or card and will dry properly there (unlike oil paint). The added advantage is that the paint will not warp even the thinnest paper, unlike any water-based paint.

Humbrol enamel paints

The enamel paints sold in modelshops (mainly for painting plastic kits) are good examples. Both brands, Humbrol and Revell, use otherwise identical tins and a similar range of colours. The Revell enamels tend to be a little thicker .. there are strong devotees of one or the other. The same distinction between ‘tough dry’ and ‘properly dry’ applies to these enamel paints. Matt Humbrol paints will be touch dry almost as quickly as acrylic, sometimes within 15mins, but it will be a further 24hrs at least before the paint is durable. Humbrol enamel paints cover exceptionally well (with much less streaking than acrylic) and dry very thinly so fine detail does not get clogged. The oil in them will rise to the surface in the tin if they are left for a long time and this means that they can have a very long shelf-life if the tin is properly closed. As a disadvantage it means that they need to be thoroughly stirred if left for a long time as the pigment and filler has separated to the bottom. They also have, like regular oil paint, a very pervasive smell, and although there are no serious health risks with good ventilation I have experienced occasional headaches and smarting eyes after working with them for more than a few hours!

The tins may look small but what they contain goes a very long way because often full, opaque coverage can be achieved with a very thin layer and the paint can be eked out with the brush to cover a very large surface without losing opacity. I would guess that a 14ml tinlet has easily the same covering reach as a 60ml bottle of acrylic for example. Both Humbrol and Revell tinlets are widely available in shops (those selling artists’ materials, hobby or craft shops, or those dealing with scale model building) and are relatively inexpensive though prices vary from one shop to another. For example the best deals are online at www.wonderlandmodels.com with tins around £1.36 including VAT whereas in shops they range from £1.50 to £1.80.

Although I’ve always been a devotee of these paints for whatever purpose, mainly because of their extraordinary adhesion and toughness, there are definite drawbacks apart from the smell! They’re designed for simple, flat coverage rather than ‘painterly’ painting i.e. there’s little blending possible and no additives such as retarders or glaze mediums available. On the other hand they adhere strongly even if heavily thinned with white spirit and can make very effective wood stains. There’s quite a good range of colours, though this is far better weighted in favour of earth colours or natural greens than strong primaries.

Tempera

The type of ‘tempera’ familiar to most people from school days comes in two forms; large plastic bottles and hard, round ‘cakes’. Both are relatively cheap, and certainly not the best pigment quality, but they can still be very useful! At around £2.00 on average for a 500ml bottle of Reeves Redimix Tempera there are at least some colours within the limited range which could serve as excellent basecoats especially for large areas. This type of tempera is also soft compared to most acrylics so it is ideal for the topcoat paint layer which has to separate easily when using craquelure medium for special paint effects. Whereas the liquid tempera appears to have a reasonable amount of binder the ‘cake’ version doesn’t so it behaves more like a cheap, solid gouache which can be wetted ‘on the cake’ where none is wasted. In UK art shops cake tempera is not a common sight apart from the children’s’ painting kits but in some other countries they have a more prominent place in art shops and there is a much more serious colour range.

The most useful brushes to have

You’ll notice from the photographs in this article that there aren’t any fine and expensive sables here! Painting brushes aren’t designed to be rubbed against scratchy surfaces or poked into tight corners, let alone used like a plunger for stippling! So there’s no point in buying expensive brushes! Synthetic brushes such as the one shown on the far right below (usually white or tan-coloured nylon or ‘Prolene’) are the most hard-wearing for this kind of work and they keep their shape well. They are not usually expensive and it’s worth having a few different types i.e. a couple of extra-fine detail brushes (’00′ or smaller), a couple of larger round ones and a few flat. The flat ones are the best to use for streak-free painting of larger areas but they are also good for dry-brushing.

brushes for model-making

It’s also useful to have some general-purpose hogshair brushes (such as the one on the left above) for thicker, textural painting especially stippling. These brushes are also better for forcing paint into tight detail such as the mortar lines inscribed in Kapa-line foam when making brickwork. A third useful type is the full, soft kind shown in the centre (in this case a calligraphy brush) because these are the best for loading when applying washes of watery paint.

Caring for brushes properly is almost as important as having them in the first place i.e. obviously they should never be left for long after painting before cleaning them. Even then, cleaning is not just a matter of rinsing them out thoroughly in the water used while painting. This will get rid of most of the obvious paint but (especially with acrylics) there will always be some which has crept up to the metal sheath (the ferrule) which is harder to remove. This will continue to collect after each use, the hairs will gradually be pushed apart and the brush will never close neatly when loaded with paint like it used to. The solution is to wash it more thoroughly in warm, soapy water after each use, using a stronger bristle brush or even a wire brush carefully to infiltrate the tight bundle of hairs at its base. It’s also worth periodically reviving brushes by doing the same using a stronger brush cleaner or more forceful soap such as ‘The Master’s’ Artist’s Hand Soap.

After brushes, the next most important piece of equipment for painting is a mixing palette or at least some kind of non-absorbent surface on which paint can be mixed and which is easy to clean afterwards. I mostly use flat, white kitchen tiles because these can be left and the paint scraped away once dry without damaging them. Occasionally a flat surface is not suitable if more than just a little paint needs to be mixed up to cover a larger area, especially if this needs to be kept for a while. Of course things like yoghurt pots will serve but I’ve found there’s more need for smaller vessels. The customised mixing palette below is a sheet of 5mm foamed Pvc plastic, light but stable, and makes use of plastic milk-bottle tops glued to the surface to hold larger amounts of paint. I’ve also included a pad of washable plastazote foam to wipe brushes on.

customised mixing palette

Basecoating and working ‘light to dark’ or ‘dark to light’

If an element of the model has been made from more than one material but will be given the same surface treatment it makes sense to paint on a unifying coat first. Dependent on the effect one wants one can start from a pale or white base and paint conventionally from light to dark, or alternatively the basecoat can be dark with further colours applied, especially if dry-brushing, from dark to lighter.

Paint can be applied to a white, or light foundation in various ways. If the paint has a fairly strong, quick-drying and ‘self-sealing’ binder (meaning that once dry the paint layer will not be dissolved by further paint applied over it) it is usually possible to apply the paint as it comes to achieve a solid and even colour. This is true of most acrylic or wall emulsion paints for example. But these paints can often be thinned down considerably and applied as washes, which should still seal themselves, so that other or darker colour washes can be applied on top with the initial colours still showing through. This is sometimes referred to as a type of glazing. By this means it is usual to build up effects gradually from light to dark. Watercolour paint and gouache are non-sealing because they contain the minimum of binder and are normally only used for painting on a suitably absorbent surface, such as paper, which goes some way in fixing them. They can be used in the same way (as above) for building up rich colours on suitably primed surfaces but preceding colours will always mix through and the contrast may be limited. Watercolour is transparent, because it generally doesn’t contain fillers, whereas gouache is opaque because it does. Acrylic is the best in terms of giving the versatility of working in very thin coats but gradually increasing colour richness, depth and contrast. With acrylic it is difficult to go back to white though i.e. to start again and repaint areas without it being noticeable or mudding the look.  

An alternative is laying down a dark colour first (or starting earlier with a dark priming coat) and applying progressively lighter colours on top of it .. working from dark to light. This doesn’t work very well with transparent paints or glazes; it is most effective using opaque acrylic, gouache or matt enamel. This is especially when there is an under-lying texture which will automatically pick up most of the colour on its raised parts, revealing the structure more (as in brass rubbing). This technique is known as dry brushing. This involves putting only a small amount of paint on the brush (similar to blusher on a makeup brush), so it is not literally ‘dry’ but certainly minimal, and lightly skimming the surface. It can be used to subtly alter or enhance colour on a light ground but it is usually much more effective when applying lighter opaque tones over a dark ground. It’s also easier to paint over mistakes with more of the basecoat colour and start again without betraying the fact. Dry-brushing tends to give an enhanced, more dramatic look because of the increased contrasts .. as if glancing light is casting stronger shadows.

wet skimming with paint

For example, above, I am skimming over the relatively prominent brick structure on this piece of black foamboard using a partially loaded brush and thin but opaque acrylic. The main object is that the mortar lines and other indentations remain darker. For the more subtle floor surface being painted below a ‘drier’ application of paint is needed to give full effect to the minute variations in the texture.

dry brushing

An even more delicate ‘dusting’ of paint was needed to bring out the raised pattern on the piece of kitchen tissue used to simulate this quilt and to suggest wear on the old leather Chesterfield.

dry brushing on model furniture

Naturalistic painting can be likened to a performance by a highly skilled actor. It can be so convincing that it feels somehow effortless and spontaneously generated .. belying the layers of thought and preparation that have gone into it!

painting brickwork_basecoat

For this wall piece using Kapa-line foam (a teaching example, hence left unfinished) I have base-coated in a sandy mortar colour instead of a dark one, so that this will remain visible in the inscribed lines. I used thinned acrylic and worked it into the surface with a hogshair brush. This was followed by randomised touches of two more colours shown below. It already looks fairly convincing as brick, but more like brick which has been sand-blasted .. too clean and evenly coloured.

painting brickwork_overlaying colours

So the final touch was using a wash of thinner, darker colour, concentrating on where the bricks are more deeply worn away, where grime would mostly collect. If this wall were in a proper model setting there would be more of this at the bottom, dirtying the meeting between wall and ground.

painting brickwork_final wash

Staining, tinting and varnishing

I’ve briefly touched upon the use of wood stains in the previous post on creating surfaces. Wood stains of various shades simulating various types of wood can be found in stores such as B&Q, and on the whole the spirit-based type are best because they infiltrate the wood fibres better giving a richer effect. But these can be expensive especially if only a little is needed and good stains or tints can also be made by mixing a little pencil or pastel pigment with white spirit, or thinning down enamel paint as also suggested. Liquid shoe polishes are also cheap and are effective either for staining wood or glazing other surfaces. The pieces of stencil card below were given a grain using sandpaper and then stained variously with transparent acrylic, bought wood stain, pastel/white spirit or liquid shoe polish.

stencil card wood-effect samples

Below are texture samples made with Polycell ‘Fine Surface’ Polyfilla which have been rubbed lightly at one end with coloured pencils, then wetted with a little white spirit. The pencil pigment blooms into life and can then be pushed around a little, blended or rubbed off before drying. It is a way of achieving subtle dirtying or colour-tinting and can even be rubbed away with an eraser after drying. Regular paint such as acrylic would be too brutal, difficult to control and would fix itself too quickly even if a very thin wash is used. Most colour pencils, pastel sticks and wax crayons can be dissolved in this way. If the surfaces are going to be handled the effect can be preserved by spraying with either fixative or hairspray.

stains using white spirit and pigment

Below, if the same technique is used on oil-painting paper or board it is possible to work up very even blends or graduations of colour. As I mentioned before re. the colour swatches I make, oil-painting paper works best for this because the surface has just enough absorbency to ‘key’ what’s put on it but much of this will remain sitting on the surface and can be worked around for a while. This will work in a similar way on plastic (i.e. foamed Pvc) which has been sanded, surfaces primed with the fine polyfilla above, and also some fine-surfaced or coated papers. Here I’ve rubbed with the flat of the pencil at one end of the paper to deposit some pigment (this is easier if the surface has some texture), put a little white spirit on a small wad of tissue or cotton-wool, and started rubbing it around to dissolve it and then even it out. The colour will lessen as one moves towards the centre and if one’s careful one can get a very even fade, even blending two different colours in the middle.

pencil wash on oil-painting paper

The test piece in the centre was to see how much of the colour can be removed with a wetted brush or with an eraser once dry. Sometimes one can get back to almost white again! This technique of ‘removal’ is almost a whole method of painting in itself .. I call it ‘painting off’ .. and doesn’t just work with pigment/white spirit. For example, if watercolour is applied as a dark wash and left to dry on a surface which is only partially absorbent (i.e. as I’ve said, absorbent enough to anchor the paint evenly but not letting the paint soak in) the paint can be removed again using water. This can be done in a very general way, using a wetted sponge or rag, but it can also be done in a very specific and controlled way using a fine, wet brush. One of the best surfaces to try this method on is oil-painting paper but suitable surfaces can be created on any base form by priming either with acrylic gesso or the polyfilla as mentioned. Apart from having to have this only partially absorbent ground what is also important here obviously is that the paint used will dry but not seal itself so that it can be re-dissolved. Both watercolour and gouache are just as suitable for this as the pigment/white spirit combination.

Metallic and gloss finishes

One conclusion that I’ve reached over the years is that it’s almost impossible to simulate the look of clean, polished metal using a paint .. as impossible as it would be to paint-on a perfectly reflective mirror surface. In place of a pigment, metal-look paints contain finely ground metallic particles which reflect light back. Often these particles are not even real metal but ground minerals such as mica which are coated and transparent dyes are added to produce a colour range from silver through to copper. The effect when applied to a large smooth surface is usually rather dull and uninteresting! Usually I recommend using a foil-covered paper or card instead. There are some that have an almost mirror-like surface and a little ink or pure pigment can be added to varnish to change silver into gold or copper or darken the surface further to look like steel or lead.

On the other hand it’s relatively easy to suggest tarnished, dulled or dirtied metal surfaces for smaller elements. It’s an interesting example of the assumptions our minds tend to make against the evidence of our eyes, that many real metal surfaces are not in fact shiny, reflective or even lustrous when viewed objectively. I’m often asked what special materials or paints should be used to simulate manhole covers, when in fact no more than normal paint is needed because on the whole there’s very little that remains truly reflective on a dirtied manhole cover. However, because we know it’s metal we picture it differently. If objects nevertheless need something special to make them look convincingly ‘metallic’ it usually needs very little! The small architectural elements below, cast in polyurethane resin and meant to look like buffed iron or pewter, were base-coated in matt black enamel. This was given more than a day to harden properly before being dry-brushed or ‘dusted’ with a special wax gilt called ‘Treasure Silver’. This is like a polish filled with fine metallic particles and is most effective if used very sparingly so that much of the dark under-painting is still visible as contrast. ‘Treasure Gold’ is commonly used and often applied to larger forms such as picture frames with the finger, although for smaller forms one can achieve more subtlety with a brush. As the polish is worked over the form the metallic particles are made to lie flatter giving a more reflective surface than paint. This can be enhanced if need be afterwards by gentle buffing with a fine polishing cloth. There is a special sealer available to protect the surface from handling.

using wax gilt

Cracked or peeling paint

I’m asked many times how best to achieve the look of cracked or peeling paint in a scale model. The best way is to use a special medium often called either a ‘craquelure’, ‘crackle’ or ‘cracking’ medium .. but the technique is not simple, and it is impossible to totally control the results especially in terms of scale. Usually the first requirement is that the surface to be treated is painted with a dark base, of whatever colour you want the cracks to be. This has to be thoroughly dry, then a coat of the cracking medium is applied over it. This also must be allowed to touch-dry before applying a top-coat of a contrasting colour. It is important that this top-coat is applied quickly, evenly and in as few brush-strokes as possible .. because too much disturbance of the layer of cracking medium can lessen the effect. This means that a soft, wide brush is usually best. Also, the best results are obtained with an opaque, but relatively liquid and weakly-adhesive paint .. in other words wall emulsion or poster-paint as opposed to tube acrylic. The cracking effect starts to appear almost as soon as the paint is applied, in other words while it is still liquid. What is happening is that the cracking medium, a form of glycerine, is stopping the contracting layer of paint from finding anchorage on the surface, so it starts separating.

using cracking medium

The size or scale of the cracking will partly depend on the thickness of top-coat applied. Here above, I managed to get a fairly fine scale of cracking by applying DecoArt liquid acrylics as thinly as possible.

Creative spraying

Being able to spray paint, as opposed to using a brush, has a number of advantages for certain tasks. Its much quicker and easier than brush painting when one has to paint a large area .. when turning a white foamboard model-box black for example. Spraying will also deposit a much thinner and more even coat than is possible with the brush and it will be touch-dry almost immediately. It’s very convenient, but there are drawbacks .. special conditions are needed for spraying because a lot of solvent vapour and paint is released into the air and much of the paint settles as a fine dust; spraypainting is therefore wasteful and some brands can be expensive; surroundings, and areas not meant to be painted, need to be carefully masked. If standard (polystyrene filled) foamboard is being used the solvents in most spraypaints will eat away at any exposed foam surfaces such as the foamboard edges. The best way to combat this is to seal those edges first by painting them with acrylic or Pva glue, then spraying once these are fully dry (i.e. ideally waiting more than a day).

There are many different spraypaints to choose from, and these vary not only in terms of the paint properties but the way they can be sprayed. Some, like the 150ml cans from Humbrol or the 300ml ‘Buntlack’ cans from Marabu, are very opaque, well-covering paints which adhere to a variety of surfaces, including plastic and metal, and which are surprisingly durable when fully dry. These release the paint at a fairly high pressure, so they are ideal for full, fast and even coverage but not suitable if you want to lightly ‘mist’ or tint with them. Humbrol offer a range of specially matt sprays but the Marabu Buntlack collection is satin-matt. The cans of car touch-up sprays found in petrol stations or outlets like Halfords are usually under much lower pressure (presumably because this makes it easier to blend coverage over a repair) so they are better for light misting. They are however more transparent .. and of course they dry glossy, unless used on a very absorbent surface such as paper.

The effects below were obtained using car sprays, depressing the spray-cap only minimally and holding the can at more distance (over 30cm). I first sprinkled granules over the paper to act as a mask .. to the left using sugar, to the right using larger granules of vermiculite. With each of these I did a light spray through them first, brushed the material off, sprinkled again, then re-sprayed with a different colour. A high-pressure spray would simply blast the granules away! Depressing the spray-cap only slightly also means that the paint droplets are a mixture of sizes, some large, which gives a more interesting effect akin to ‘toothbrush splatter’.

spray patterns

Although I’ve tried many different types of spraypaint in the past my preference now is for graffiti sprays such as the Montana Gold or MTN 94 ranges. I’ve found that these combine most of the best qualities of all the other types. They’re commonly very opaque, matt, quick-drying and sufficiently durable .. available in a very good range of strong or muted colours. In particular the MTN 94 range has especially ‘low pressure’ making it suitable not only for controlled blending but focused spraying of small elements. These specialist sprays are also amongst the cheapest .. rather surprisingly! Currently the 400ml cans of Montana Gold cost £3.80 and 400ml MTN 94 £3.60, including VAT at Chrome & Black in London www.chromeandblack.com Buying from a specialist shop such as this also means that they will have a variety of replacement spray-caps to vary how the paint can be sprayed.

I do most of my spraying work outside, but for small work I use an improvised cardboard spray ‘box’ for working inside which doesn’t eliminate the smell but stops the spray-dust from travelling. I’ve cut widows in this to let in light and covered them with clear acetate.

improvised spray-booth

I’ve already recommended the use of Simoniz brand spray primer in the previous post, shown on the left below. This also comes in a neutral grey and a brick-red, both of which make very good basecoat colours in themselves. Simoniz doesn’t make a matt black primer specifically, but their regular matt black spray can be used for this and it is one of the strongest and cheapest matt black sprays I’ve found so far.

paint primers