Where to look for ready-made forms

I’ve compiled a new page List of sources for ready-made forms which I’ve put in the Materials section under ‘shaping’. If you’ve ever searched for something just the right size for puppet eyeballs, wondered whether you can get mini ‘taxidermy’ domes or whether there’s maybe a ‘magic’ way of making model bottles, you may appreciate this list and some of the tips included. I’ve copied the introduction and a short extract from the list here.

inside 4D modelshop, London

There are many instances where being able to take advantage of a pre-formed shape could not only save a lot of time but also opens up exciting possibilities .. promoting the work beyond one’s technical means. But often the thought of having to take the ‘time out’ to hunt down the right something is a dissuader, as is the notion that somehow using something ready-made is a bit of a cheat! I started this list originally to encourage myself to make more use of the ‘ready-made’ by having a quicker overview, but also because whenever I came across useful ‘things’ I never knew where to note them down for the future.

I’ve tried to divide the list into categories as far as possible, so here is the ‘Table of Contents’:

Discs especially small, in various materials; Domes flattened or semi-circular, whether thin/hollow or solid, including taller display domes; Spheres or balls whether hollow or solid; Ovals in 3D; Wheels and cogs; Teardrop shapes; Cones mainly solid; Straight dowels, rods, cylinders i.e. solid, circular in cross-section; Small rigid tube mainly plastics and metals; Larger round tubes including cardboard and plumbing supplies; Patterned rod or tubing because there are some; Curved or bendable rods, flexible tubing to include foams, Pvc and silicone, cable supplies; Rings; Trumpets, funnels etc; Eggs wooden or polystyrene; Blocks  ‘off the shelf’ and lastly Other forms for the rest.

Each section is organised by supplier and the underlined product titles are from the online catalogues so you can find them more easily in searches. The fact that this wording is sometimes specific and unpredictable is the reason why I’ve bothered to make a separate list in the first place .. after all, one could just do a Google search as/when needed .. but unless one uses many different search words some possibilities would always be missed! Prices were last updated in May 2016, all adjusted to include VAT. I haven’t just listed the cheapest, rather those suppliers who seem to offer the most useful range. If you have anything to add to the list your suggestions will be welcome!

 

Trumpets, funnels, ‘bottle’ shapes and superglue dosers

Heatshrink tubing or ‘sleeving’ is made from polyolefin plastic ( i.e. polyethylene, polypropylene ) and commonly used in electronics/electrics for wire insulation or bundling. It shrinks uniformly when heated with a heat gun, usually in the ratio 2:1 meaning it becomes half as small. It comes in different diameters and the clear versions are ideal for making small-scale ‘bottles’. Finer heatshrink tubing also makes very good ‘dosers’ for superglue work, to attach around the existing nozzle if more precision is needed (Poundland includes a few already in their packs of superglue bottles). I should note though that you will need a heat gun (preferably a small one) to shrink the tube uniformly as shown below.

clear-heat-shrink

www.cablecraft.co.uk

Easi-Shrink’ Heatshrink Sleeving available in small diameters 1.2 – 6.4mm, and bigger sizes up to 100mm. 3.2mm diameter is ideal for 1:25 scale bottles (since these are commonly 8-9cm wide). Price for clear 3.2mm £0.83 per metre.

heat-shrink tubing

www.e-deala.co.uk

1ml or 3ml pipettes e.g £10.99 for 500 3ml pipettes

1ml and 3ml pipettes

I’ve included these because there are sections that can be cut to make reasonably good model bottles (from the thinner 1ml) or glasses depending on the scale you need. Bear in mind that this polyethylene plastic is never ‘glass’ clear, it has a slight frosting.

www.modelshop.co.uk

Plastic funnel set 50, 75, 100 and 120mm diameter £1.85

plastic funnel set

www.partypacks.co.uk

Plastic party glasses are a good source of shapes, but online suppliers don’t usually list measurements except capacity in ml.

Clear Brights Plastic Champagne Flutes’ 148ml (like image but clear, uncoloured) £4.14 pack of 10

plastic flutes

 

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Cutting smooth holes in foam

I chanced upon this method of making almost perfect holes in rigid foam after I was asked about the best way to do the same in cake .. making holes to take tube supports between storeys of a wedding cake! For this I very roughly carved ‘teeth’ in the end of a plastic plumbing pipe, which as it turned out could be twisted into the cake without a problem. So I wondered whether something similar would work for other materials. I was fairly certain it stood a chance of working if I could cut the teeth finely enough, and for this a slightly harder form of PVC pipe is needed .. MuPVC ..which stands for ‘modified unplasticised polyvinyl chloride’.

I’ll need to cover this briefly first. The various plastic waste/drainage pipes you’ll see in any building supplier or DIY store (whether white, black, grey or brown) are likely to be two or more different plastic types. They will either be polypropylene (PP), ABS (a form of styrene), uPVC or MuPVC. MuPVC is harder than the others, but actually easier to cut or file cleanly because it is slightly more brittle. The only sure way of identifying it is finding the letters ‘MuPVC’ as part of the printed info along the side of the pipe, but also if the pipe is referred to by the store as ‘Solvent Weld’ it’s very likely to be MuPVC.

hole-cutting tools for rigid foam

Obviously there are only a few available diameters when it comes to these pipes and it depends on the store which ones they actually have. Standard outside diameters start at 22mm and normally end at around 44mm .. before they become something else, i.e. drainage or guttering pipes which are either brown or black. At the moment in the UK Wickes has the best selection of MuPVC .. 22mm, 36mm, 40mm and 50mm .. but don’t search for ‘mupvc’ in their online catalogue because that will only bring up one of them. Instead find the sub-section ‘Plastic pipe’ in ‘Heating & Plumbing’ which should show all the others, just described as ‘solvent weld’.

Wherever and whatever you find, the supplier normally should list the pipe according to its outside diameter, not its internal one. For more technical details see ..

http://www.hendersons.co.uk/pipework2/page2.html

squaring end of Pvc pipe

After trialling a few ways of making the ‘cutting’ edge, I found this to be the best method. Firstly, the end needs to be cut and filed/sanded straight i.e. at 90 degrees to the pipe length, as above. Then, using either sandpaper wrapped around a dowel or a round file, the thickness of the cut edge needs to be reduced to almost a point, as below. This should be a gradual slope (over 5-10mm) and on the inside .. the outside diameter remains constant.

chamfering end of Pvc pipe

The next job is to file the ‘teeth’ and I would recommend using a small-size power drill and a diamond-coated bit .. if you have those things. If not you have to do it by hand using a round needle file, but again, I’ve found the diamond-coated needle files more effective on hard plastics. The box of diamond-coated bits below is from Rolson, found in Maplin, costing around £5.00 as I remember.

fine filing tools

For each of the ‘teeth’ shown below I held the drill bit or file at a slant outwards from the centre of the ring and also slanting forwards around the ring, as saw teeth normally are. This may look painstaking, but it wasn’t really .. it look a while, but the plastic sanded comfortably. I made the teeth on the inside of the pipe so that the hole cut might be smoother.

finished 'teeth' on pipe

These tools worked well on the three types of rigid foam I work with .. blue styrofoam (extruded polystyrene); Kapa-line foamboard (polyurethane foam), and ‘Recticel’ another polyurethane insulation foam sold in thick sheets i.e. from Wickes.  Below, the pipe is first positioned on the foam and then turned very carefully until it has some purchase. After that it needs only moderate pressure while turning, making sure to keep the path of the tube straight .. the angled teeth will draw the tube in. Recticel is very soft and fibrous, but the tool still managed to make quite a smooth-sided hole.

turning foam 'hole cutter'

cutting holes in Recticel PU foam

I made use of the technique for the sculptural pieces I’m working on at the moment .. i.e. this prototype base shape for casting, which is meant to take a number of peg forms.

base unit shaped from styrofoam

 

Coating styrofoam with polyurethane resin

These are the latest forms I’ve been making for my .. not-quite-working-title .. Ridiculously Organic Construction Toy. For this I’ve been creating simulations of eroded rock and driftwood cast in resin, twisted Pvc branches covered in fake moss and lichen, corals, leaf clusters and strands of seaweed made from latex etc. But I also wanted to include some play elements which are more obviously scaled down, such as these brickwork ruin pieces. The best way of picturing the whole idea is to think of aquarium or reptile tank accessories and then imagine getting a large collection of these instead of a box of Lego. I’m still working on the question of how exactly the ‘construction’ is achieved .. i.e. how such components will be fixed together when playing .. but as part of the system I’m working on an artificial ‘mud’ which I’m hoping will solve part of it.

ruin fragments in resin-coated styrofoam

The forms above were cut/carved in regular blue styrofoam, textured using a heavy-duty wire brush and then coated in polyurethane resin. There’s a bit more to the ‘painting’ process .. something new I haven’t tried before .. but I’ll come to that. If properly done the method of resin coating makes the forms unbelievably strong! .. perhaps not enough to survive little children, but certainly any adult wear-and-tear.

Making a brickwork arch in styrofoam

These two photos illustrate other forms intended for the collection and the process of making them. I’ve described this method of form-making in more detail in Shaping styrofoam. The arch piece above started with a Pvc template, which I used to help sand a block shape. I found I had to make a separate drawing template (the one at the bottom) just in order to inscribe the brick pattern onto the styrofoam shape. Then I used the special diamond needle files pictured to scratch out the brickwork divisions at the right thickness. I wanted these pieces to be 1:12, i.e. usual dollshouse scale, but I’ll eventually use a mixture of scales.

Making a brickwork niche in styrofoam

To make the ruined ‘niche’ shapes above I also used the method I described in Shaping styrofoam of using a curved sander to create the concaves. I roughed out very deep channels for the mortar lines, because these will become partially filled with coloured resin .. and this is what gives the pieces unusual strength. I found it was better to make all the channels before attacking with the wire brush, because I made the pitted texture mainly by hitting or pressing with the brush. This peppers the foam with deep holes and it may fragment a bit too much if the channels are made afterwards.

diamond needle files

Here is a close-up of the type of file I’ve found to work best for detailing foam. These have a ‘diamond coated’ surface which has more of an effect on relatively soft materials than the other, cheaper, form of needle file which is just ‘toothed’, grooved metal.

wire brushes useful for texturing rigid foam

I usually use the smaller brushes pictured above when working with the more delicate polyurethane foam in Kapa-line foamboard, but styrofoam has a tougher surface .. the heavier wire brush has more effect. Importantly, the action in this case is not a brushing or sweeping one, it’s more hitting downwards and rocking around .. I call it ‘scumbling’.

styrofoam 'ruin' fragments

Now to get to the main point of this article! Of the polyurethane resins I most often use (Sika’s Biresin G26 and Tomps’ Fast Cast) I know that both can be used in the following way, but Tomps Fast Cast is best because it’s a little thinner, powder pigment mixes better into it, and according to Tomps it is designed to cure properly in very small amounts or in very thin layers. This is not the case with all polyurethane resins. I’m basically making a very quick-setting paint with it, and because it’s quick-setting it has to be done a little at a time. To dose both resin parts I use disposable plastic pipettes (which are available from a few places online) and usually work with not more than 2ml of each part at a time. I can normally manage to use up to 4ml before it thickens too much. Because there’s usually no time spare to clean the palette surface before it sets I use a ceramic tile which can be scraped clean afterwards. There’s always just enough time to clean the brush though, and this can be quickly done with acetone.

Coating styrofoam with polyurethane resin and pigment

Here I’ve dosed 1ml of each resin part together on the tile, added a small amount of powder pigment, mixed the whole together with a synthetic-hair paintbrush and used the same brush to paint the foam. Synthetic is best because the hairs will be rigid enough to push the pigmented resin into deep pattern, but full and fine enough to hold a lot of the paint. Powder pigment is the best form of colour to use .. strong colour, inexpensive, available .. and I usually find that it mixes better into resin than it does with water!

The polyurethane resin has no effect on styrofoam (unlike polyester resin), it will cure hard and ‘fused’ to the surface, and it’s done .. that is, it’s touch-hard and ready for further work .. in about 15 minutes! Whereas regular paint such as acrylic will infiltrate more and contract as it dries, polyurethane resin does less of both so there will be a little ‘smoothing over’ of fine surface detail. It will also be a gloss finish! .. which I don’t like, would never choose, and at the moment I’m experimenting with the different  ways of dealing with this. There is no matting additive for polyurethane resin, and regardless of which pigment or filler is mixed with it, the top surface exposed to the air will always be glossy. Obviously painting over with another matte paint, such as a good acrylic, is an option .. but polyurethane needs a lot of preparation if the paint coat is to resist a lot of handling and this is made difficult by such a patterned/textured surface.

One possible solution is to use my own version of cold powder coating. If you google ‘powder coating’ you will find that this refers to an industrial painting process in which fine thermoplastic powder is melted onto metal to create a durable surface. It’s very like the enamelling that you might have done at school, with coloured glass powder on a copper plate, melted in a small oven. My version does not require heat, and it’s perhaps more related to the model-making practice of scattering granules into glue to create a surface .. but it does share some of the surprising durability of these other methods!

crushed brick

Below is a close-up of the styrofoam ‘ruin’ forms after coating. I first gave the bare styrofoam an undercoating of resin mixed with black pigment, and then a second coat without any pigment, covering a small area at a time. While each portion was still wet I sprinkled a mix of finely crushed brick and sand onto the resin. I’m fortunate in that, living close to the Thames beach, I can pick up fragments of any colour of brick, illustrated above. Since these have already been broken down by the elements they are much easier to crush to a powder using mortar and pestle.

detail of brickwork surface done with 'powder coating' method

While working I could see that the particles were readily sinking into the thin coating of resin, and when the excess is shaken off after a few minutes the powdery top layer still adheres strongly. Polyurethane resin is a strong adhesive, especially if the dust or particles are porous and jagged. Having tested the strength of the surface once the resin cured I have little doubt that it is permanent. I still have to do some paint finishing on these pieces, emphasizing contrasts and colours and giving more ‘speckle’, but I have no worries about regular acrylic paint attaching itself on top. The greatest bonus in this particular case is that these pieces have a lot of the look and feel of real brick .. because that’s what it is!

 

Making a non-slip ‘gripping board’ and a bench hook

polyester grip fabric

I would imagine you’ve all seen this material or something similar .. textured rubber sheets for placing underneath rugs or mats to stop them sliding about. I’d bought this version from Poundland a few weeks ago for another idea which in the end didn’t work and so it was pure coincidence that I had it still lying around when I had to cut a lot of Pvc piping for another project. I’ve never bought myself a proper bench vise .. that probably says something about me, though I don’t know what .. and in the past I’ve made do with something like the setup below, the pipe slightly raised on a cutting mat with perhaps some kind of coarse cloth underneath for extra grip. It’s always worked, more or less, but it’s never been comfortable. Cutting mats grip the table well enough for normal knife cutting but rather lose it when the force acts across them .. such as when sawing.

trying to support Pvc pipe for cutting on table

So I tried a few cut pieces of this grip liner underneath and pressed down firmly in position as I would normally do, and I have to say that it worked incredibly well! Although there was a little give, it felt as if the pipe was in some kind of vise. By the way, as you’ve seen .. for once I prefer the American spelling as opposed to ‘vice’!

polyester grip fabric as support for cutting or sanding

I could have just left it like that and it would have been enough of an improvement, but I felt I was onto something and wanted to make a proper ‘gripping block’. I clad both sides of a piece of 8mm MDF with the material, using double-sided carpet tape to stick it down. The carpet tape needs to fill the surface, otherwise the grip material may ruck when the block is used. I thought initially of using rubber glue to attach the material but the carpet tape holds it well enough in place and it means that it can be easily replaced.

cutting block surfaced with polyester grip fabric

I call this a ‘gripping board’ rather than a ‘cutting board’ or mat because I hadn’t intended it to be cut ‘on’ so much, it’s more about helping to hold things steady while cutting slightly ‘off’ the edge of it, but there’s no reason why it couldn’t be used for both especially if a softer base such as chipboard is used. I found that the board gripped anything, round or flat .. plastic, wood or metal. It was just as beneficial when sanding ends or edges, as below.

sanding with gripping block underneath

I tried various thin strips or rods of metal which I’d hitherto only been able to cut using a small metal vise I have .. and it was, again, almost like having a vise! I find it bothersome to set up the vise every time I want to do this and it’s difficult to keep the surface of the metal undamaged.

using gripping block for cutting metal

I found it worked even better after I made a small ‘finger block’ surfaced with the grip fabric which meant that I could press down more firmly without crooking the fingers uncomfortably.

using gripping block with additional 'finger plate'

I’ve always thought I should make a bench hook so this was a good time to try my own augmented version! I just used a piece of laminated chipboard I had (this one 15cm wide, 20cm long) attaching end-pieces of timber (25mm x 15mm) firmly screwed. The screw-heads need to be countersunk!

simple bench hook build

The ‘bench hook’ is so-called because it hooks along the front edge of a work table to provide steadiness while sawing .. at least on the forward stroke! They have been around for centuries, and making one often used to be the first project in school woodworking classes. Here, below, are a couple of manufactured ones .. from http://www.badaxetoolworks.com

manufactured bench hooks

If I’d bothered to look at examples like these before I very hastily put mine together I would have made the timber end-pieces a little short on the right side (for right-handers) as shown above, so that the block could be sawn ‘on’ .. but I wasn’t using the right kind of wood for this anyway.

Nevertheless my idea of covering the working surfaces on both sides with the grip fabric turned out to be a significant improvement, because it gave even more steadiness on both forward and back strokes. Since it is only attached with double-sided tape the fabric can be easily replaced if it gets too damaged.

bench hook with grip cladding

using bench hook

I also found it very useful to have both the bench hook and the simple mat for supporting lengths of wood while cutting.

using mat as extra support

 

More work with styrofoam

I’ve made some additions to my .. according to the statistical accounts .. most visited page Shaping Styrofoam which is under ‘Shaping’ in the Materials section. One is that epoxy resin glue works very well to bond it! I’d always assumed that epoxy would damage it, in the way polyester resin does .. but no, it doesn’t dissolve it and the bond is very strong! .. and I’ve used the cheapest stuff around, the one from Poundland! The other addition deals with preparing styrofoam prototypes for mouldmaking and I’m reproducing the entry here. I’m also finally managing, by the way, to hint more at what I’m up to at the moment .. working towards a solo exhibition of my current sculptural work which will take place in or around September next year!

If a styrofoam shape is being made as a prototype form intended for casting it doesn’t need to be made particularly durable .. it only needs to withstand silicone rubber being either brushed or poured over the surface. It does however need to be sealed, because if not the silicone rubber will grab into the surface too much and become very difficult to separate. Vaseline (petroleum jelly) is an ideal temporary sealant in this case because it can be easily brushed or rubbed into the micropores without damaging the surface. If care is taken not to use too much of it the Vaseline will also even out the surface, although I’ve noticed that most of it is absorbed into the silicone anyway. The only problem is .. it’s very difficult to see where you’re applying it! The solution is to colour it.

base unit shaped from styrofoam

This is one of many base-unit prototypes I’m making for a sculptural work which I can describe best by its working title .. ‘the ridiculously organic construction toy’! The components of the ‘nature driven’ form system will be assembled by means of holes and joining-plugs, hence all the holes in the base. Once I’ve made the mould from this the base units will be cast in polyurethane. I found a laughably easy way to carve out clean holes in styrofoam and I will explain this method sometime soon.

pigmented Vaseline

The best way to colour Vaseline is to first mix a little powder pigment, in this case half a teaspoonful, with roughly the same amount of Vaseline to make a thick paste not unlike tube oil paint. I chose the ultramarine here because it’s a strong pigment and finely ground, combining smoothly with the Vaseline .. some powder pigments may be grainy or clump a bit, which is not so good! The half teaspoonful was sufficient to give a strong colour to c. 50g of Vaseline when I added this to it, but one could use far less pigment. For example, the pigment will stain a porous prototype, so you have to bear this in mind if you want to keep it or if it’s an object of value.

using coloured Vaseline to seal styrofoam

There were a couple of larger scratches in the surface which I needed to fill and I’ve found that soft modelling wax (this one is the Terracotta Modelling Wax from Tiranti) is the easiest to use, worked carefully in with a brush.

filling larger holes with modelling wax

That’s actually it .. surprisingly short this time!

More on gluing, surfacing and repairing styrofoam

I’ve been slowly adding to my page on Shaping styrofoam in the Materials section, partly because I saw that it was one of the most visited pages. I wanted to consolidate the scraps of knowledge I’ve gained over the years on gluing styrofoam and the range of options for finishing or reinforcing the surface. I also wanted to look into a more satisfactory method of making repairs which I found, as you’ll see from the photos  .. well, very satisfying!

More on gluing styrofoam

I’ve bonded pieces of styrofoam together with a strong, double-sided carpet tape for years and they’re actually much more permanent than I’d first imagined. I have composite forms made many years ago which have been well-used as teaching examples and show no signs of coming apart! A few observations are necessary though! .. the two surfaces have to be smooth and flat against each other; if these surfaces have been sanded to make them fit, all dust should be removed, ideally vacuumed using a brush attachment. For the same reason the best bond occurs between the slightly ‘skinned’ surfaces of the sheet as it comes. When using the tape it’s particularly important to avoid placing it too near to where the styrofoam will be carved or sanded if one wants a seamless join .. but this applies almost equally when using most glues. But if it’s impossible to predict, or avoid, gluing in an area which will later be carved through or sanded, I’ve found some of the following options most suitable because they offer the least resistance.

For example what works surprisingly well as a bond between flat styrofoam sheets is spraymount, by which I mean the permanent spray-glue types from 3M. 3M’s ‘Craft Mount’, which is the strongest of their range, is particularly suited because it has a little more body. It should be sprayed on both sides to be joined (different to how it’s normally used), and it’s best to wait a little i.e. half a minute, before the two pieces are firmly pressed together. As with all contact glues, even the ‘instant’ ones, the bond will hold straight away but needs a day or two to get stronger. But the same applies with this as with double-sided tape .. the surfaces must be completely flat against each other and dust-free to bond strongly enough! Spraymount never sets completely hard, even though it’s grip is strong. When cutting through a glued edge the glue may catch the blade a bit but one can get used to this. It will sand reasonably well, especially if the tackiness gets mixed with styrofoam dust. For the same reason, I’ve found that it can help to dust the piece with talc while sanding.

If you want to glue pieces of styrofoam together which do not lie completely flat against each other .. you will need something ‘gap-filling’. There’s hardly anything more gap-filling and instant that hot-melt glue! Contrary to what you might have read elsewhere, hot-melt glue will work reasonably well with styrofoam .. as long as it’s not too hot! One just has to know how to manipulate it. Polystyrene foam is much more heat-sensitive than polyurethane foam .. it softens already at 90°C (193°F), while the temperature of hot-melt glue is around 180°C or more. So there is bound to be some melting of the styrofoam surface, but if you experiment and are careful you can find just the right number of seconds to wait before pressing the surfaces together, cooling the glue down a little but not so much that it fails to stick. Obviously it’s not possible to cover a whole surface, even a small one, with hot glue before most of it hardens. Think of this more like ‘riveting’ .. applying very quick spots of hot glue which will secure the pieces at those points once the glue has cooled. This method is definitely not for carving into or sanding though.

Another option is provided by the ever multi-tasking polyurethane! It’s common practice in scenic work and prop-building to use a rigid-setting, 2-part polyurethane foam to bond other foams such as styrofoam together. A small amount of the two parts must be mixed together in the directed ratio and then brushed quickly onto the joint before the foam pieces are pressed together. The resulting foam will expand to fill any gaps in the joint but the pieces must be held firmly in position while this is happening, otherwise they’ll be forced apart. Often this is easier said than done because the expanding foam exerts quite a force, but generally with these polyurethane foams and glues the less gap there is the stronger the joint will be. Prop-makers and sculptors are more likely to use the foams which are supplied in two separate parts and which need to be manually mixed .. a good source is a sculptor’s supplier such as Tiranti .. but the ‘instant foam’ tube cartridges sold for wall repairs or insulation are similar.

Gorilla glue is yet another option .. a polyurethane glue that comes as one part, so no mixing is necessary, and which foams while curing on contact with moisture. What this means is that both surfaces to be glued need a light misting first .. best with a small pump spray. The glue needs to be applied thinly to just one of the surfaces before the two pieces are pressed together. Below are two blocks of styrofoam already sprayed .. just enough to dampen the surface, certainly not dripping wet!

Gorilla Glue test, styrofoam moistened

Gorilla Glue can be deposited in spots if preferred, and these will spread once the pieces are squeezed together. It is not necessary to spread the glue beforehand over the whole surface but here I used a coffee stirrer just to distribute it better. What is very important to note (and not included in the manufacturer’s directions!) is that the glue should be dropped from the nozzle without letting it touch the wet surface! If it does moisture will contaminate the bottle and some of the glue will set inside .. as I found out when I tested it for the first time!

Gorilla Glue test, applying the glue

Below, I have weighted down the two pieces with a solid metal block. This was sufficient, although where possible it is always better to clamp the pieces together (sandwiched between flat pieces of wood to protect the styrofoam). The expansion occurs after a minute or so, 3-4 times in volume according to the manufacturer, and if the pieces are properly clamped the excess is forced outwards rather than upwards. If, because of the shape of the pieces, it is difficult to clamp without damaging the surface, masking tape or cling-film could be used to bind them together but these could give way a little and there may well some shifting as the foam expands. I had to correct the alignment of these blocks a few times before the foam stopped moving them.

Gorilla Glue test, weighting down

A couple of hours are needed for the glue to cure. Here below is a section through the seam line, cut with a knife then sanded. If it is properly cured the glue sands through well …. although it is different to the styrofoam it is much more alike than other glues. Also the bond is as strong as they say it is! I think polyurethane grabs on the styrofoam particularly well .. at least, I couldn’t pull the blocks apart.

Gorilla Glue test, section through the seam

More on surface treatments

If the surface is going to be reasonably protected .. I mean, if it’s not going to be handled and if it’s shielded from knocks etc. .. a good coat of acrylic paint may suffice. Acrylic paint will toughen the surface slightly, but by no means protect it from any handling, even if careful. Coating first with non-waterproof Pva glue and then painting will do a little more, and the same applies if coated with Pva or a water-based varnish afterwards. But the surface will still be very susceptible to scratches or dents.

If Paverpol is added to the paint mix .. more than half by volume .. greater surface strength can be achieved. Paverpol is a Pva-type medium manufactured in the US mainly for the hobby market and is intended for painting on fabrics or foams to give them a much tougher surface. For example fabric will become rigid and almost ‘resin-hard’ if soaked with it and the manufacturer recommends it for outdoor sculpture. It will not impart the same degree of toughness when painted on styrofoam because it doesn’t infiltrate far into the surface, but a couple of coats using Paverpol will be stronger than either regular Pva or acrylic alone. On its own Paverpol is quite viscous (a little more so than straight Pva glue usually is) but with careful brushing can be worked into a detailed surface without clogging it noticeably. In fact, whether applied straight or mixed with either powder pigment or acrylic paint for an opaque colour, the first coat will emphasise much of the porous foam surface and appear matt with an even roughness. If this is allowed to dry completely (needing a good few hours or preferably a whole day) and then painted again, the pores will start to be filled. Especially if combined with careful sanding between each coat using a medium grit sandpaper (for example 120-200 grit) a fairly smooth finish can be achieved. This must be applied as evenly as possible because raised streaks in the Paverpol will be tough to sand down!

Paverpol fabric strengthening medium

The next option is either painting or coating with a ‘polyfilla’. I make this distinction between ‘painting or coating’ because certain polyfillas can be thinned with water to a gesso-like consistency without losing too much of their strength and can be smoothly painted on. Polycell Fine Surface Polyfilla is in my experience the best of these. It is bought ready-made in tubs; it’s particularly smooth; thins evenly with water; sticks very well to sanded styrofoam and is far less subject to shrinking and cracking than other types. It also retains a little flexibility when dry. To get an even, lump-free cream with water it’s best to ‘condition’ some of it first either in a bowl with a spoon or on a clean glass plate with a spatula or palette knife. As you work it around it will become more liquid and if this is continued while adding water a few drops at a time you will gradually get something like the consistency of gesso, without any lumps.

The forms below were carved/sanded in styrofoam; the sanding stage finished with a flexible foam-backed sanding pad (see below) to achieve the smoothest surface. They were then painted with a thin coat of Polycell’s Fine Surface and left to dry for a day. After this a second coat was applied and then a third, which was left as before. The final treatment before painting was a careful sanding with a very coarse (60 grit) sandpaper which imparted a visible grain, softened with an overall rub using finer (240-300 grit) sanding cloth. The surface achieved with this polyfilla is not any tougher than the Paverpol, but it is much easier to sand, making it more ideal if the aim is an even, glass-smooth one. I painted these with Humbrol matt enamel, which is thin enough not to clog surface detail or add any additional texture but opaque enough for a rich and streak-free coverage.

Finished forms in styrofoam, coated in polyfilla, re-sanded and painted

I waited a few days for the paint to reach maximum hardness (although thin, the enamel dries very hard and durable) then rubbed carefully with a fine sanding sponge (these look similar to kitchen washing pads) to bring out some of the grain.

But an equally smooth and even harder surface can be achieved using a more specialized material. Casting resin is not usually considered as a medium for thin coating, mainly because it’s thought that it will fail to cure properly under a certain thickness. This may be true of some, but I’ve used both general-purpose (GP) polyester resin and special types of polyurethane resin many times for this, mixing in very small amounts and applied like a varnish .. with consistently good results! Polyester resin cannot be used to coat styrofoam because the styrene part of it will eat into the surface. However, polyester resin will work perfectly on polyurethane foam and, with predictable logic, polyurethane resin works perfectly on polystyrene foams such as styrofoam!

Uncoated and coated styrofoam 'heads'

The ‘head’ on the right above was painted with a small amount of Tomps Fast Cast polyurethane resin, first mixed together quickly and then worked with a soft brush into the styrofoam surface. I chose this brand because of its low viscosity, designed to cure even in very thin sections. After about an hour this cured enough to be sanded, just to even out the surface a little, before being coated again. More careful sanding followed, and finally one more coat. The overall coating is now akin to eggshell in thickness and hardness .. but in important respects stronger because it is supported uniformly by the rigid foam underneath. An ‘industrial’ ceramic-look smoothness can be achieved using a mixture of careful rubbing with special sanding ‘cloth’ (blue/green below) or thin layers cut from the surface of a nail parlour sanding block. These will flex with the shape, unlike sandpaper. Polyurethane resin sands surprisingly well for something so hard .. even easier to sand than some fillers!

Foam-backed and cloth-backed sanding materials

Below I’ve included the stages in the shaping of these ‘heads’ .. starting with a block shaped on a template, then sanding away from a centre line.

Stages in styrofoam shaping

The concaves for the eyes were started with a curved sanding tool, similar to the one used on the form at the beginning of Shaping styrofoam. These are easy to make, involving only a thin strip of sandpaper glued to a former.

Custom sanding tools for making concave shapes in foam

Major repairs or alterations to styrofoam forms

It is a long-established practice amongst carpenters and, in more recent times, restorers to neatly excise a damaged area .. i.e. to cut it neatly out .., glue a new block of the same material in its place, and then reshape this rather than ‘bodging’ with something else like a filler. Most fillers tend to shrink, to varying extent .. inevitable if they rely for hardening on the evaporation of a solvent. They usually can’t be laid on too thickly otherwise they can take an age to harden, and it may take a few goes to fill a deep repair properly. The other disadvantage of using fillers, especially to repair or alter styrofoam is that when set the filler material reacts very differently to sanding than the surrounding foam. It is usually much harder and inflexible, making a seamless transition difficult. The much better way to do it .. patching in with the same material .. is illustrated below.

This test form was made in the same way as one of the components described above .. first rough sanded and then finished with a 120 grit sanding block.

styrofoam repair demo test form

Below is some stylised ‘damage’ ..

styrofoam repair demo 'damaged' form

I sanded away a broad channel, making sure that the bottom of it was flat and smooth. The side edges are not parallel but a little tapered, so that a wedge-shaped block can be slid into position. This means that the block doesn’t need to be perfectly accurate in width.

styrofoam repair demo, damage cut out

In this case I secured the block with double-sided carpet tape. I’ve found Ultratape ‘Rhino’ very reliable so far. The block needs to be slid into position, as I’ve said, but not pressed down until it’s tight against the channel edges. I also slanted the edges of the block a little i.e. making the top surface a little bigger than the bottom, so that when pressed down it squeezes even more tightly into place. Styrofoam will compress a little to make this possible.

styrofoam repair demo 'patch' inserted

Then it was just a matter of re-attaching the semi-circular templates either end of the form (see earlier) to protect the undamaged surface and sanding the block down to the same point.

styrofoam repair demo 'sanded flush'

Just out of interest I tried similar repairs using Gorilla Glue as a filler ..thinking that, since the glue takes so well to the styrofoam and cures with a similar composition it might be an ideal solution. Unfortunately not!

Gorilla glue as filler, test piece

I made some notches with the scalpel, spray-moistened the styrofoam surface, then laid the glue into them making sure to spread it completely over the edges of the cuts. I also spray-moistened the topside of the glue after this was done.

Gorilla Glue as filler, cured foam

I waited a little more than two hours, during which the glue had expanded .. as the manufacturer says .. 3-4 times in volume. The first few millimetres of the cured foam was fine-pored and sandable, ideal in fact, but deeper down the bubbles were much bigger and the consistency soft and fibrous. It was like trying to sand bread! The foam had become weaker and more irregular because it was allowed to expand too much and I’m guessing that it would work better as a sandable filler if it were more confined i.e. by wrapping a non-stick covering over the form before the expansion starts.

Gorilla Glue as filler, sanded down

‘Model-making Basics’ – modelling and shaping

Please note before you start reading this older post that I have long since included a version in the Methods section, under Making realistic models, which can be accessed above. That version may have been updated or expanded since.

This is the third 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 .. in other words the ‘ways of thinking’ behind the practical work .. and this is followed by a selection of ‘ways of doing’ giving more specific and practical guidance on the materials and methods used.

As I see it, ‘modelling and shaping’ encompasses the making of any element in the model that cannot be achieved by methods of construction. That is, if a form or part of a form cannot be achieved by cutting sheets or strips of bought material and assembling the pieces, it means that it has to be either shaped or modelled. So for example this would include model figures and trees; forms of relief decoration which are more than just cut outs; the making of specialized forms such as globes, domes, bowls, niches; soft furniture such as armchairs, sofas .. I’m sure you get the idea! Some of these things can be bought, including figures or trees, but usually the likelihood that these are ‘just the thing’ is slim. It’s very easy to persuade oneself that it’s a good move if it will save hours or even days of time, so one should guard against ‘cheating’ oneself by compromising on what one really wants. Nevertheless it is worth knowing what the options are for a number of difficult forms, such as transparent globes or domes for example, because believe me unless you are a highly experienced maker there’s no easy way of making such things oneself. 1:25 scale figures can be bought and are often used, but again I’ve seen too many examples of their careless use in theatre design models to want to recommend this solution.

It’s expecting rather a lot of a theatre designer to be a good sculptor too, especially a good sculptor of miniatures! .. and modelling is traditionally the province of the sculptor. For this reason ways have to be found of keeping within one’s ‘comfort zone’ in terms of knowledge and skills. You can’t know and be able to do everything! There’s no such thing as ‘cheating’ here (except in the case of cheating yourself, as above). What counts is that you’ve done what you can to make the model look as you want it to look, and it conveys your design intentions, regardless of the means you’ve employed. Most ‘serious’ sculptors have tricks which they don’t like admitting to for whatever reason and a number of those are included here. But any method of getting the job done which you imagine a serious sculptor may frown on .. is in this context probably worth a try!

GENERAL APPROACH

The difference between ‘modelling’ and ‘shaping’

The main thing is .. ‘organic’ shapes with little geometric regularity such as human figures or trees are more easily modelled, whereas more streamlined forms such as domes or niches are more easily achieved by controlled shaping. Modelling is generally additive, usually starting with a support then adding an amount of soft material, then adding more, etc. .. modelling is ‘pushing a soft material around’ until it’s where you want it to be. Shaping, at least the kind I do with the materials I’ve chosen, is generally subtractive .. the form usually starting as a block which then has successive parts taken away from it until the intended form is all that’s left. One major consequence of this difference is that modelling can usually be back-tracked if a mistake is made whereas shaping usually cannot. If too much modelling material is added or if it ends up in the wrong place it can be removed or moved, whereas if too much is taken away when shaping wood or foam it can’t be put back. For this reason modelling feels more free, there’s room for improvisation and chance, and there’s room for taking risks and making mistakes because these can be smoothed away if they don’t work. In fact modelling has to progress in this manner. Shaping on the other hand needs a different ‘mindset’ .. it needs to be more anticipated and must be quite tightly planned, leaving little room for chance or experiment.

Choices of modelling material

Of all the materials for modelling available now, natural clay remains the most reliable and versatile, in addition to being the cheapest by far. In its fresh state it is one of the softest, smoothest, and can be made more ‘liquid’ very easily, so it can be almost ‘smeared’ on when fresh, and successive layers fuse with each other readily. As it loses water it firms up, allowing more detailed modelling, and even fine carving at the so-called ‘leather hard’ stage. But as it dries it also shrinks and cracks, small forms are very fragile when dry if left un-fired, and larger forms are heavy .. so unfortunately it’s not suitable for model-making. But a number of different modelling materials have been developed which either remain in a soft, workable state for much longer or harden by themselves.These have a range of different properties, but they can basically be grouped into three categories (though some overlap more than one). Incidentally, I’m just going to say ‘clay’ from now on in place of ‘modelling material’ as a general term.

There are the plasticine clays which remain soft and workable almost indefinitely, even after long exposure to the air. Most of them cannot be made hard and durable. Their basis is usually an oil or wax (at least something other than water) and a filler, such as finely powdered natural clay or talc. Examples modelling wax, plasticine, Chavant, plastilene, etc. Polymer clays such as Super Sculpey can be hardened and more properly belong to the third group, but if they’re not baked they will remain workable for as long, at least as long as plasticine. In my experience modelling wax is the leader of this group .. at room temp firm but softens quickly, does not stick to fingers, can be smoothed with hot tools. Many waxes can be melted to a liquid state in order to be poured into a shape (only some ‘plasticines’ can, such as the American Van Arken brand). Here in the UK the ‘Newplast’ type of plasticine in long blocks is probably the easiest clay to obtain, and relatively cheap at an average of £1.80 for 500g. It is easy to model with, although when very soft I find it too sticky .. it gunges up finger-tips and is not ideal when impressing with texturing tools etc. Importantly though, plasticine will accept coats of Pva wood glue, which toughen the surface and allow it to be painted. Pva wood glue contracts a great deal as it dries so there is usually no danger of losing detail in the modelling, even after more than one coat.

Modelling waxes

Modelling waxes, plasticines and polymer clays all come in different hardnesses .. at least, certain brands do. Above are two types of modelling wax, the brown one very soft like natural clay and the white one much firmer. For more on working with these see Modelling wax in the Materials /- modelling section.

There is a significant, but subtle, difference between modelling waxes and plasticines in terms of their surface behaviour when being modelled, which some may find fairly crucial but others may not. It’s a bit difficult to describe, but on the whole modelling waxes have less elasticity meaning for example that if you impress a cocktail stick against the surface you will get an exact groove with quite hard edges. If you do the same with plasticine (and particularly Super Sculpey, which is even more elastic) you will also get an exact groove but the edges will be more rounded because the material there has been pulled down a bit. In other words, plasticines and polymer clays are a little more rubbery, and this can save time if you’re going for smoothness. But on the other hand it means that these materials have a significant ‘push-back’, a little resistance to being pushed around, which can make very fine and sharp detail a bit more difficult. Generally the softer modelling waxes are similar to natural clay in having really no ‘push-back’ at all.

To get back to the three basic types of clay .. the second category is the air-drying materials which all share having water, in the place of oil, as a carrier and these will harden as the water evaporates. Since some of their content is lost in this way they will shrink .. and some of them will shrink and crack badly!  Examples  natural clay, Paperclay, Newclay, Claydium, Das, etc. Many have a fibrous texture which helps in holding them together but often makes fine detail difficult. Some are light, some are quite heavy. Pricewise they are very good; after natural clay some are the cheapest clays around! I usually only use the air-drying, pulp-based clays if I want to built up a rough core modelling shape easily and cheaply, but only if I’m not bothered about cracking or the time it will then take to dry.

The final category includes those clays which will set or ‘cure’ as the result of a chemical reaction, brought about either by two reactive parts being mixed together or by heating. Examples Milliput (2-part epoxy putty), Green Stuff, polymer clays. My firm preferences from this group are two, Super Sculpey and Milliput. They are very different materials to model with and I use them for very different purposes.

Super Sculpey (that’s the full brand name for this type unfortunately, not just me being enthusiastic!) is almost as soft and ‘pushable’ to model with as a soft modelling wax and just as non-sticky ‘finger friendly’. It doesn’t stick to itself as readily as soft modelling wax or natural clay but it will with just a little extra coaxing. I prefer it for modelling medium-sized forms which need a combination of surface detail and smoothness .. a puppet head with sculpted hair for example .. because I find smooth contours much easier to achieve with it than wax, but at the same time very detailed textures can be achieved by imprinting with texturing tools. Super Sculpey can be easily modelled up in layers, heated in between. More on this is included later when discussing model figures. The only characteristic of Super Sculpey that I don’t like is it’s very slight translucency which sometimes makes it difficult to judge surface detail. There is more on Sculpey in the summary page I’ve included in the Materials /- modelling section. Below is an example of a small fish form I had to make in Sculpey which needed to be baked and fitted into a curve, so I had to rig up a curved cardboard support for modelling it on. Small forms don’t take so long to bake so in this case the cardboard survived the hot-air gun.

modelling a stylised fish in Sculpey

Milliput’s main distinction is it’s hardness once fully cured, much harder than a polymer clay. I use it for small or delicate forms which I really want to last .. small, because Milliput is more expensive than Super Sculpey. It is much more difficult to model freely with, having far too much ‘push-back’. The two component parts of Milliput need to be mixed together in equal amounts and the window for modelling before Milliput becomes too hard is 1 – 1.5 hours. For more information on Milliput, there is quite a long entry in the alphabetical Lexicon.

Just for the heck of it, out of interest and for those of you who are really price-conscious here is a comparison I put together earlier this year. I have taken prices from the sculptor’s shop Tiranti in London, which I know are fairly average or ‘reasonable’ .. not the cheapest but certainly not the highest! I have compared the price per kilo even if the materials are not normally packaged in this amount and where there is a price range it reflects the cheaper price for larger amounts:

Natural clay £0.47-£1.27 per kg £11.88 per 25kg, £6.37 per 5kg

Newclay £1.19-£1.96 per kg £15.08 per 12.6kg, £8.83 per 4.5kg

Newplast £3.56 per kg £1.78 per 500g 10% off 20

Claydium £3.94 per kg £1.97 per 500g.

Plastilin (Flints) £5.10 per kg

Modelling wax Terracotta Wax or Scopas White Modelling Wax £9.29-£12.72 per kg £46.45 per 5kg, £6.36 per 500g

Chavant £10.45 per kg £9.48 per 907g

Milliput Standard £20.10 per kg £2.28 per 113.4g

Super Sculpey £20.64 per kg £9.37 per 454g

Milliput Fine White £44.62 per kg £5.06 per 113.4g

Green Stuff £156.33-£240.50 per kg £4.81 per 20g, £9.38 per 90cm

The principle of ‘controlled limitation’

This is not an ‘official’ phrase but one I have assembled myself to help me to think about it. It is a principle behind all successful making but applies particularly to modelling and shaping. It makes me think of ‘damage limitation’ and conjures up a film scene of soldiers building a strong barrier around a bomb to contain the blast. Perhaps ‘containment’ would express it just as well.

I remember always being very impressed, and equally relieved, hearing about the ways sculptors make their lives easier! For example making a block of wood firstly into a rough profile shape of the whole head, to define the limits .. or rather to remove what one was certain one didn’t want first .. before going further. Working in the other direction (i.e. building up rather than removing), I was impressed when I saw the method of sticking long nails into an emerging clay head to set the positions of key points on the eventual surface.

But put sculptors aside for the moment .. without doubt, craftspeople are better at coming up with ingenious ways of making their lives easier! The photo below illustrates a delightful technique called sledging which is still known to some traditional plasterers, used to create profile shapes particularly for wall cornices. After some basic volume has been roughed in using coarse plaster, a layer of finer plaster is shaped by dragging a cut metal profile along it which collects and removes the excess.

sledging a shape

Another example for a more complex form is provided by the schoolmaster/model-maker Thomas Bayley in his truly precious book The Craft of Model Making, last published in the 1970s. Here he shows how to tackle interior alcoves and domes by first making a positive shape from which a shell cast can be taken. He recommends making the main shape of the positive by means of, what he terms, ‘running with a template’.

Thomas Bayley 'The Craft of Model Making'

These methods may offer a manageable solution if one has time and patience, but they are by no means simple to achieve, even the first example! One does also need quite a bit of skill and practise. I include them here because they are more important as examples of the type of thinking that one should do .. thinking in terms of templates which control the material and limit the ‘damage’, but also ‘thinking in negative’ which there will be more about later.

These methods of control all apply to making larger-scale forms and are designed for precision .. whether of line, smoothness or detail. When it comes to modelling on a smaller scale a lot less precision is needed .. one can often get away with good ‘suggestion’ rather than realistic depiction. This, together with the fact that things like weight and structural integrity are not such issues at a smaller scale, means that the solutions for modelling forms or creating shapes can be more free and varied, that is .. not tied to conventional sculptural methods.

For example below I am modelling a figure directly onto a drawing, without using an armature. The idea with this is that the complete front half is modelled, the material is then hardened, after which the back half can be continued directly onto it. The big advantage here is that the drawing imposes clear limits i.e. it is almost impossible not to get the general proportions and shape of the figure right if one keeps to the drawing.

modelling on a template _1

I’m using Super Sculpey here, a flesh-coloured polymer clay which, as I’ve said, is one of the softest and most malleable. It hardens with heat, which means that the usual way is to bake it in a normal oven (130 degrees centigrade, c.15 mins for each 6mm of thickness used), but it can also be hardened quite well using a hot-air gun, which is better for the task here. One needs to be careful though, when heating the figure up, that the paper template doesn’t start buckling too much with the heat. Normally I’d suggest having the paper glued down to a board, but it’s better if the paper is not because then it’s easier to peel away from the baked first half without damaging it.

The disadvantage of this method of ‘modelling flat on a template’ is that obviously it works better for forms which keep mainly to one plane, as with this figure ‘standing to attention’. It helps a lot to have copies of the drawing close to the modelling, as below, and it’s pretty essential to work out a clear side-view to be able to check the thickness being built up. As I mentioned, a conventional sculptor would not work this way, arguing that one can’t get the same sense of the overall three-dimensionality and poise of the figure while working. But for the purposes of suggesting figures in a model, whether they’re there as characters in the drama or features of the architecture, I think the benefits of being able to keep to a template outweigh the shortcomings.

modelling on a template_2

I’m not suggesting that all model figure work can be done this way. Normally a sculptor builds up a modelled figure on an armature, which is a skeletal support for the figure usually out of wire, and it makes sense to do that even at this small scale. Getting the armature right is more than half of the task, at least in terms of importance. A good armature is not only there for structural support, it should also be as far as possible a guide as to where to put the clay .. it should impose some control. The small figure armatures below are ones I’ve featured in my book, but I describe a quicker method later when we look more closely at figures. The ones below are made of soldered brass and they include double thicknesses of brass on the legs and arms but broken at the joints so that these can be bent at the correct points. They also include flat plates (in brass shim) representing torso and pelvis, which although not strictly necessary for support, are invaluable for keeping the sense of the shape of torso and pelvis while modelling.

small figure armatures

Below is a fuller sequence of photos which illustrate the use of ‘controls’ when shaping soft foam and the usefulness sometimes of having a harder ‘core’ shape to model on. For this task I had to make a 1:6 scale model of an ornamented fireplace, including two large fish sculptures either side. This was for a film still in production, so unfortunately copyright prevents me from showing the completed fish forms until the film comes out, but I can show enough to illustrate the modelling process. Because the fish needed to be symmetrical I decided to make the same basis shape for both out of styrofoam, cutting a template shape first out of Pvc for one and using it flipped over for the other. Below, I have secured the template shape to a block of styrofoam using double-sided tape, which holds it firmly while shaping but which can be easily detached afterwards.

fish base form_1

Knives and wood rasping tools can be used to get close to the edge of the template shape ..

fish base form_2

.. but I prefer to use a sanding block and more ‘control’ to reach the line. I’ve made a round sanding block from a cut piece of thick cardboard tube (the kind used for rolls of carpet or upholstery fabric) with 60-grit coarse sandpaper attached.

fish base form_3

The sides of the sanding block are at a right-angle, so if both the form and the sander are kept against the work surface while sanding, at least the basis blocks for each shape will come out the same.

fish base form_4

I then sanded (or rasped) these freehand, but both at the same time .. i.e. a little off one, then the same off the other .. until I reached the right shape below. Unfortunately I didn’t take a photo in between the two here in this case, but the best next step would be to shape down the top surface on each block first before doing anything else, because this slope can be easily compared. After mostly using a coarse wood-file, I finished off the form below using a small piece of coarse sandpaper. I’ve begun to press the first layer of clay (in this case I’m using Super Sculpey) onto the styrofoam. Because Sculpey really doesn’t want to stick to styrofoam, it was important to work it in thinly at first to ensure a stable coating before adding more.

fish base form_5

Below, I have built up a good, even layer ready for the modelling of the surface details. Making a block styrofoam core-shape like this has a number of advantages .. it means that the modelled shape has a more controlled basis as I’ve said, just like the wire armatures; it gives a firm basis for pushing against, particularly if surface details are achieved by pressing or imprinting, without the fear of pushing the overall form out of shape; it economises on modelling material (some, like Sculpey or Milliput, are expensive compared to natural clay); and it reduces weight, without making the form itself much weaker.

fish base form_6

A note of caution though! .. I modelled these fish in Super Sculpey and didn’t need to harden them because I was making moulds and casts from these prototypes. Heating a very thin layer of Super Sculpey on styrofoam (using a hot-air gun) can distort the styrofoam shape if it gets too hot. If you’re using this method for a one-off where you need a permanently hard surface a thicker Sculpey layer (i.e. c. 5-6mm) would most probably be ok, because the styrofoam would be partially insulated. Otherwise you have to use Milliput or another self-hardening clay.

In the section ‘Making curved shapes in styrofoam’ later on I demonstrate another method of controlling a shape using specially shaped sanders. These are not things one can buy but they can be easily made. I found that only a thin strip of sandpaper was necessary to sand styrofoam (or the polyurethane foam from Kapa-line foamboard you will see later). If this strip is supported on a shape it means that the area of foam sanded will gradually take that shape and this will work for convex as well as concave shapes.

sanding shapers for foam

Developing the ‘scanner eye’

Some people are good at looking at a subject, whether it’s standing before them or recorded in a photo, then looking at the copy they’re making and recognizing how the two differ .. i.e. what exactly needs to be added to or subtracted from their copy and where. Usually it’s something they’ve acquired and developed through a lot of practise at looking at things, so it’s a skill that theatre designers in particular should have already and be particularly disposed to developing. It’s a fundamental of being able to model a likeness! I believe that simply improving your ability to look at and compare things objectively is the most important step towards acquiring skill in sculpting. For example, next time you’re on a train compare the shapes of the heads you see around you. Try to estimate how big people’s foreheads are in relation to their heads as a whole. Are hands bigger than faces, is the length of a nose roughly the same as the distance from it to the bottom of the face, is the space between the eyes the same as the length of an eye? These are simple things to try, you can devise your own questions, and this type of conscious looking won’t fail to improve your abilities if you practise it whenever you have a spare moment.

‘Thinking in negative’ or approaching the form as a void to be filled

Up to now I haven’t included the methods of mouldmaking and casting within this series because they’re more specialised, a whole other subject in itself, and I’ve already written a general summary of it Beginner’s Basics – Mouldmaking and casting explained which can be found under Methods /- Mouldmaking and casting. But I’m including this brief example here because it illustrates a different approach to making a form. It is a method of form-making which goes back a long way and is now an integral part of our technology. I’m sure most people are aware of the principles of it, but almost exclusively in the context of ‘making many copies of something’, which somehow prevents the recognition of it as a solution to making single forms.

The challenge of making a model of a bath is a very good example of what I’m talking about! Most often we only need one, and we know that ideally it should be as thin as possible, so our thinking is automatically channelled in the direction of trying to construct the shape in a thin but bendable material. This would be fine if the curves and slopes of the shape were that simple. If however we think of the essential shape as a solid one first, so that we start with a three-dimensional form template in other words, a lot more is achievable.

making a bath shape

These two photos are enough to illustrate the method. I’ve made the ‘prototype’ bath shape using the foam from Kapa-line foamboard (which I’ll say more about later) but styrofoam would also have done. For the fish shape previously I used one shape template to guide the sanding block, whereas this needs two to establish the limits of the top and bottom of the shape. These just need to be fixed in the right positions either side of a rough block of foam and the excess foam is then sanded away down to the edges of both templates. Finding the right positions for the templates, either side of a block, is not that simple though! The best way is to fix the larger template to the foam first and sand down to that using a right-angled sanding block (just like the fish). This will give a much clearer indication of where the smaller template should be positioned on the other side. The sanding can then be completed.

making bath shape in foam

I coated the foam shape with polyfilla and sanded it smooth, then made a plaster mould from it. In this case I made the hollow bath shape using a fairly simple process known as absorption casting. The principle behind this is that the plaster mould will absorb water from a liquid material filling it, meaning that the material gradually forms a tougher skin next to the plaster. The remaining still-liquid material can be poured out of the mould leaving a thin shell which is left to dry. This contracts a little as it does so it can be taken out easily. It’s the method used, on an industrial scale, for casting crockery using clay slip. I’ve used a special form of liquid papier-mache called Liquache which is not so available in the UK (but I’ve included one source in my Suppliers list). An alternative would be to use the more familiar method .. the beloved ‘balloon pasting’ one .. of papering the inside of the mould with small pieces of newspaper and glue. The mould surface would need to be Vaselined first though. In actual fact, if the thin shell is built up this way there’s no need to make the negative mould at all .. it could be built up on the prototype form, as long as it’s strong enough.

PRACTICAL GUIDANCE

Making model figures

Let’s just assume for the moment that making three-dimensional scale figures to inhabit a three-dimensional scale model is a good thing, before arguing the pros and cons of having to do them! The first thing that’s needed is information. We need to know what the human figure looks like and, just as importantly, what it looks like at 1:25 scale. When I’m modelling in 1:25 scale I work from visual cue sheets such as these ones. For these I’ve taking the trouble, not only to find the clearest, most authentic looking and most general models for the proportions and details of the human figure but I’ve also adjusted them all in size to fit the 1:25 scale. It doesn’t mean that every bit of visual reference I have needs to be in scale as long as I’ve got this basis.

female figure reference sheet

For these I’ve looked at various sources .. anatomy books for artists, figure reference websites, medical books .. but the visual references I’ve found most helpful have come from reliable digital artists such as www.selwy.com One can usually tell at a glance whether the artist really understands figures, and the neutral grey or brown surface of a digital sculpt is much easier to read than even the best real-figure photos.

male figure reference sheet

Before one can begin modelling though, an armature is needed. As explained above the armature supports the material but it should also serve as a modelling guide. In my post from March 2013 Modelling small-scale figures I provide a step-by-step account of making the simple armature out of twisted garden wire below.

1:25 scale twisted wire armature

The template which is useful as a size guide during the process is also included in the post. The twisted surface of the wire has an added usefulness in that it gives more ‘tooth’ for the clay to attach itself to.

making wire armature

In my opinion it’s much easier to model a figure at this scale when it’s ‘spreadeagle’ i.e. laid out flat like a five-pointed star, keeping the joint areas free almost until the last. This way it’s easier to portion out and balance body and limb masses, getting a symmetry first. Super Sculpey lends itself in particular to this because very small amounts can be applied first of all just to put some mass on the skeleton, and these can be quickly fixed with the hot-air gun before putting another layer on top. It doesn’t matter how many times the same portion of figure is subjected to the hot-air gun for successive layers as long as it’s not too close (i.e. not nearer than about 5cm) or dwelling too long on one point. Either the figure or the heat gun needs to be kept moving .. but slowly, not agitated.

building up the form

Milliput is the next best alternative material to use, and some might prefer it. I’ve used it on part of the figure above right and for the whole of the middle stage below. Milliput is a 2-part epoxy putty, and the parts need to be mixed in equal amounts before use. After thorough mixing one has between 1-1.5 hours to work with it before it becomes too tough to model. An advantage over Sculpey is that it’s much stronger, especially when making very slender forms and it’s much stickier. But for this reason I don’t like it as much as it sticks to the fingers and makes detail modelling sometimes difficult. It has much more ‘push back’ than Sculpey, especially so after just half an hour. It also makes the process of building up in stages quite a lengthy one because a few hours are needed before it’s safe to model the next layer.

stages of modelling

Modelling tools

For modelling figures at this scale the question of tools is hardly important .. in fact I often just use a cocktail stick and a Starbucks coffee stirrer! Basically it’s enough just to have something finely pointed and something flattish.

modelling in Sculpey

But if you find that you are doing a fair amount in the way of modelling, and larger things, here is a selection of the most useful bought tools. The four on the left are standard ones for clay modelling and one can get them in plastic or wood. In the centre are two made from walnut strip wood and to the right of these is an embossing tool. This is useful because it has two rounded points of different gauge. The metal dental modelling tool to the right of it is an example of a range of fine-modelling tools one can pick up quite cheaply (even in £shops sometimes). To make modelling easier it can be quite important to have at least one of the ‘loop’ tools shown next to it. These make it possible to remove material rather than just displacing it.

modelling tools selection

But just as much can be achieved using tools which are not meant for modelling, especially when it comes to surfacing effects. Below is the fire part for the fireplace mentioned earlier, modelled in Super Sculpey. A plastic bristle brush and a hogshair painting brush were perfect for giving the burnt wood and coals a suitable surface texture.

texturing Sculpey

Other useful texturing tools can be made either from natural forms such as this portion of nectarine stone or modelled and baked in Sculpey itself. The form to the right, which was designed to imprint a tree-bark pattern was modelled on a cutting-knife blade so that it could be fitted into the handle.

special texturing tools

Soft furniture

Rather than modelling the form of an armchair or a sofa out of clay .. this is possible, especially for broken down old things which are any shape except ‘streamlined’,  but they can end up rather heavy .. I use soft sheet foam to make them. Take this old leather Chesterfield as an example of perhaps the most ambitious, alongside something simpler. Kapa-line foamboard has a polyurethane foam inside which is quite dense and fine compared to the polystyrene foam in regular foamboard and the covering paper can be quite easily peeled away without damaging the foam surface. The foam can therefore be used as a versatile sheet material in its own right.

soft funiture using sheet foam

peeling paper from Kapa-line foamboard

Unfortunately I don’t have ‘making of’ photos for these ones, but the process is simply one of cutting the constituent pieces (seat, back and arm shapes) as flat foam cut-out shapes first, then shaping parts of them either before or after they’re all put together. To give a better idea here is the drawing I use as a scale guide for making the small armchair

armchair drawing

Both pieces of furniture were made entirely out of foam except for the legs. Apart from the advantage that Kapa-line foam sands easily and smoothly, it bonds very well with superglue and because of its porous surface accepts any type of paint very well .. including even ink or watercolour! If painted with these or very thin acrylic the surface will look matt, even velvety, with a slight tooth to it like upholstery fabric. But it’s easy to make it smoother, as I’ve done with the leather Chesterfield, by giving it more than one basecoat of acrylic and finishing off with some liquid shoe polish.

styrene chairs

Here again are the chairs made from styrene strip plastic from the previous article on  Fine construction. The chair cushions are Kapa-line foam and I’ve incised very slight lines with a pencil.

styrene chairs painted

Below are foam cut-outs glued to Pvc furniture pieces ready to be sanded down into more rounded upholstery shapes (it’s easier to sand them after they’re fixed down).

using foam for upholstery

For the characteristic ‘quilting’ effect on the Chesterfield, more properly referred to as buttoning I think, I just marked out the pattern before gluing the pieces together and made the indentations by pressing in the corner of a small metal ruler. For the larger- scale pieces below I marked out the pattern, carved into it partly with a scalpel and rounded with a sanding board.

chair cushion buttoning_1

chair cushion buttoning_2

If the surface is coated with thinned Pva glue tissue paper or even soft kitchen roll can be laid on top and pushed into the pattern for more of a fabric effect.

chair cushion buttoning_3

Making curved shapes in styrofoam

I normally use the most common blue form of styrofoam which comes in sheets 2.5cm thick (although thicker sheets can also be found). There are also other types of styrofoam, differentiated by colour. The pink one here is finer and the green one is coarser.

types of styrofoam

I’ve chosen one of the simplest examples first to underline the basic principle of using template cut-outs to control the shaping of the foam. This is just a little step up from the previous example of the fish shape, and it’s much the same as the example of the bath shape, but I think it will help to make the more involved example of the ‘dome’ shape which follows a little clearer.

This sequence is taken from another article Shaping styrofoam in the Methods section. In it I describe the making of simple ‘half-column’ shapes as part of a composite structure, and below is one of the end results.

finished half-column

The first step in making this was to cut a piece of Pvc representing the base dimensions of the half-column (I use Pvc out of habit but cardboard can also be used as long as it’s more resilient than the styrofoam when it’s sanded). I’ve fixed the base templates firmly to the foam with double-sided tape, but they can be easily detached. Next I sanded down to the template using the right-angle sanding block shown above.

small blocks

After this I attached a Pvc semicircle either end, again with double-sided tape. Most of the part that needs to go can be sliced down with a knife if one’s careful, but then it’s straightforward using the sanding block to sand down to the curve, provided it’s longer than the piece itself so that it’s ‘stopped’ by the two semicircles.

setup for sanding curved surface

The principle behind making a regular dome in foam is similar in that it involves setting up template shapes, but this time they remain inside the form rather than attached temporarily outside. The method is suitable for any number of form variations. The faint lines of the plastic inserts are just about noticeable under the surface of the finished dome below.

dome shape

The following photo sequence shows a form with a slight variation on the regular dome shape but will serve to illustrate. The first step is to cut the Pvc shapes which will provide the ‘control edges’ or limits of the form. As I’ve said, these parts will stay within the form.

making a dome shape_1

This particular shape needed to be more ‘pill’ like i.e. a little longer than a sphere, so I had to make a flat section in the middle first, shown below. For this I used some layers of Kapa-line foam sandwiched between the two plastic templates (made in much the same way as the bath shape earlier on except that the two template shapes are the same).

centrepiece of dome shape

Each quadrant of the form is then built up in layers of styrofoam, fixed down with double-sided tape.

making a dome shape_3

I’d advise building in layers rather than a thicker block because a Pvc template can be included on the top of each layer, to further control the shaping as shown below. Here I’ve started to remove the excess with a coarse wood file, judging by eye. But I made a

making a dome shape_4

couple of curved sanders (shown in the last photo), to the same curve as the principle semicircle, in order to sand the foam down to the template ‘stops’ smoothly. As I said at the beginning, shaping certainly needs to be thought about beforehand and thoroughly planned. The thinking may be involved but the doing of it is relatively easy, and once

making a dome shape_5

one’s practised a little it opens up many form-making possibilities.

making a dome shape_6

Perfect ‘bowl’ or concave shapes are much easier, again making use of the fact that a thin strip of coarse sandpaper suffices to sand through styrofoam. The photo below is also taken from the article Shaping styrofoam in the Methods section, and shows the shape near completion. I first inscribed the size of the circle needed as a guide while sanding. I made the sanding tool to the same diameter, with a c.6mm strip of coarse black sandpaper attached. When the tool is pressed against the foam and revolved it will make a rough depression at first but this will get smoother as it continues. For more on this and how to make a round-topped alcove shape as an extension of this method see the article mentioned.

sanding a smooth concave

Liquid modelling

Again this is my term of convenience for the technique of ‘piping’ a liquid material onto a surface, as one might do when decorating a cake, to create the effect of relief decoration without the effort that more conventional modelling or carving would involve.

relief decoration

Here I am using a relief medium I have prepared myself .. Polycell ‘Fine Surface’ Polyfilla .. with a little water added to make it just a little more liquid. It should be mixed as-and-when needed because the consistency is perfect for piping evenly when fresh but after a while (i.e. after a few days) it starts to become a little lumpy.

relief decoration_2

The main trick is getting it into a suitable, squeezable, small plastic bottle with a fine nozzle. It isn’t difficult to find these. The one above was from a £shop and contained glitter-glue and so were the pen-like ones below. I’ve had to mix the polyfilla thoroughly with a little water first in a small container, then fill a plastic syringe and use this to transfer it into the bottles. If not applied too thickly the polyfilla takes 1-2 hours on average to dry. I prefer using this polyfilla mix because it shrinks the least of the various materials I’ve tried. It also dries the quickest and if deeper relief is needed a second layer can be applied, as I’ve done with the portion of picture frame in the top photo.

mixing up polyfilla

Idenden Brush-coat, which is a texturing compound commonly used in the theatre here, also works very well. An advantage of this is that it can be used as it comes without dilution and will consequently keep its consistency much longer. But unless you have access to a friendly scenic workshop, Idenden will be expensive because it only comes in 10litre buckets.

Other possibilities are offered by various fabric relief paints or glass-painting relief outliner shown below. The Pebeo ‘Touch’ relief paints are more like a liquid plastic, so one can ‘draw’ with them very evenly, and there are various colours including good metallic such as gold or pewter. It is a little disappointing that they shrink quite significantly, so they don’t manage something like the picture frame, but are perfect for the suggestion of a relief surface. The Pebeo ‘Cerne Relief’ glass-painting outliner is a thicker medium and the small tube comes with a much finer nozzle, so very detailed effects are possible.

relief modelling media

Working with wire mesh

I usually categorise my use of metal mesh as a method of shaping .. if not modelling even, because it’s also ‘pushing a soft material around’ in a way. I work mainly with ‘welded wire mesh’ which is welded firmly at each intersection, so that different forms can be produced according to where the mesh is snipped and how the free pieces are bent. It’s ideal for small tree forms, for example.

wire mesh trees

snipping wire mesh

I’m sure many other structures can be made in this way .. but that’s something for another day ..