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!

Using plaster as a filler in polyurethane resin

I’ve been asked this question a number of times now .. whether regular plaster can be used as a filler for resin, in place of the other ‘white’ powders more commonly used such as talc, chalk dust, marble dust etc. Don’t forget that these are all versions of calcium carbonate and are chemically inert, whereas plaster is calcium sulphate and certainly not as ‘inert’ since it reacts so strongly with water. I hadn’t ever considered it as a filler, and hadn’t heard of any cases of it being used in regular practice. My advice up to now had therefore been to avoid it, because I assumed that it could affect the curing of resins. Plaster is hygroscopic meaning that it will readily absorb moisture from the atmosphere however well it might be stored. Powder pigments are the same, and I have found that the slight moisture in them will cause polyurethane to foam and expand a little even when just a little pigment .. i.e. up to 10% by weight of resin .. is added. So I always assumed that adding a more substantial amount of plaster would cause bigger problems .. not only affecting cure but probably also thickening the resin too much to pour properly. Yesterday I finally found the time to do some tests using a couple of regular plasters with polyurethane resin and discovered that although there are some adverse effects these could also be turned into benefits.

Expansion of polyurethane resin when filled with casting plaster

For the first test above I made a control mix of Tomps Fast Cast polyurethane resin without any filler .. 15g of each part, so 30g total. The mix set touch-hard in just a few minutes as normal, becoming a pale ivory solid (the cup on the left). I then did the same but added an equal weight (30g) of Crystacal R which is a fine, hard, ‘alpha’ casting plaster. As per usual with polyurethane resin, the whole amount of filler has to be mixed thoroughly with Part A before adding the hardener Part B.

Whereas mixing is usually very smooth using conventional fillers such as Fillite, the plaster/resin needed a lot more stirring before the lumps disappeared. But after some effort the two combined making a smooth but thick liquid .. like treacle. As usual though, this thins down quite a bit once Part B is added, and the resultant mix was still very pourable. Far from the reaction being slowed down by the plaster I found that the cup started to get warm very quickly, and then the liquid started to expand. Once it had set touch-hard it had practically doubled its volume, as shown by the initial mark I’d made on the cup. The mass was solid, hard and ‘dry’ within 30mins .. there was no under-curing, failure to mix or greasiness on the surface .. all the indications of a good cure!

comparison of volume of 30g unfilled resin with 30g plus plaster filler

What was completely unexpected was the change in tone .. from the normal clean, pale ivory to something slightly darker, dirtier as shown here .. and I can’t really explain that yet! The test piece detached cleanly from the cup and the surface was smooth as shown below. The only indication of foaming was minute but noticeable pocking of the surface towards the top, none at the bottom.

I measured the volume increase compared to the control pour, both before and after foaming. The control pour measured 30ml in volume once solid, roughly consistent with the SG (‘specific gravity’ or weight per ml) of the combined resin parts given by the manufacturer as 1.1g. The volume of the same amount of resin with 30g of Crystacal R added .. before expansion .. was just 40ml. This is also consistent with the way plaster behaves in water, absorbing much of the liquid volume. The volume of the expanded mass once set touch-hard was 70ml.

effects of foaming visible on cast surface

I expected a roughly similar result when I repeated the test using the same proportions with pottery plaster in place of Crystacal R  .. but the result was more dramatic! Pottery plaster is a coarser, softer-setting ‘beta’ plaster, called ‘pottery’ plaster because it’s designed for making the absorbent plaster moulds ideal for slip casting. In the first place whereas the 30g Crystacal had combined with the 15g Part A resin eventually as a smooth liquid, the same amount of pottery plaster became a thixotropic paste rather like car body filler. Addition of Part B thinned it considerably but it was still a significantly thicker liquid than that obtained using the Crystacal.

expansion of polyurethane resin when filled with 'pottery' plaster

But more importantly, foaming was more ‘aggressive’ producing larger bubbles and until it set hard the mixture expanded to almost three times its original volume. As before though the mass became solid and hard within 30mins with no tackiness or other evidence of failing to cure.

larger-scale foaming on surface using 'pottery' plaster

However, as shown below there was more noticeable damage to the cast surface in the topmost area because the bubbles here had become much larger. As with the Crystacal the volume of 30g resin combined with 30g pottery plaster prior to reaction was 40ml, but this expanded to 115ml before setting firm.

larger-scale foaming visible on cast surface

I made a sectional cut through the upper parts of both test pieces and sanded the surface .. the fine casting plaster to the left and the pottery plaster to the right below.

cut sections showing foam structure

I can only account for some of this marked difference in behaviour. The fact that the pottery plaster appeared to thicken the mix more is predictable .. it is because of the shape of the particles. Commercial fillers such as Fillite are composed of minute microspheres which roll over each other meaning that quite a lot can be added to a liquid without affecting its flow too much. The particles of pottery plaster must be jagged, causing them to clump together whereas those of the Crystacal must be finer and smoother. As for the stronger foaming reaction and increased expansion .. the pottery plaster was older than the Crystacal and may have acquired more moisture; it may also contain an additive; or it could have something to do with the particle size. I’m not entirely sure!

I imagined though that whereas plaster would never be a sensible option for flawless casting, these results could have some uses. At the moment I’m making cast versions of pieces of driftwood to use as components in a sculptural project. So far I’ve been hollow-casting these in polyurethane resin, but using Fillite as a thickener. I’ve described this casting process in my article Making hollow casts in open or closed moulds in the ‘Methods’ section under ‘Mouldmaking and casting’. One difficulty with this technique is getting a thick enough build-up, especially on vertical surfaces, when using polyurethane resin because there is no way of making it truly thixotropic. I tried the pottery plaster/resin mix for coating these moulds below, with a little black pigment added. I found that because of the swelling it was much easier and quicker to build up a thick shell, even on the vertical parts.

making a hollow cast in polyurethane resin

I also found, as I’d observed from the cup tests, that since the foaming is largely directed upwards there was no damage or loss of detail on the cast surfaces. The intricate patterns of weathered wood have reproduced perfectly here!

hollow casts using filled polyurethane resin



Recommended websites for visual research

You’ll find this list now under Visual research in the Methods section, and I’ve illustrated it with examples taken from some of the websites listed. I’ve compiled it with scenic designers in mind .. set designers for theatre, film or television .. but I’ve included a section on ‘Costume and fashion’ and the list should also be of relevance to prop-makers. Apropos ‘subject divisions’, I think I still need to work on these .. I’ve divided it according to instinct and feeling, but it may need a bit more logic. Like many things on this site, it is a work-in-progress, meaning that it is meant to develop over time even if this is hardly perceptible.

The so-called 'Hobbit House' built by an eccentric artist in the Cotswolds

Above from .. the so-called ‘Hobbit House’ in the Cotswolds Below from .. Eric Eakin’s collection of bedpans.

Eric Eakin's bedpan collection

I will always be on the lookout for interesting additions to this list, so if you’d like to recommend any yourself don’t hesitate to get in touch. I’ve given preference to websites with high visual content obviously, but the quality of supporting information has been almost as important. The Internet is a vast and far-reaching resource for all of us .. the task of making it more ‘responsible’ is one we all share!


Why not just Google?

A while ago I thought it might be useful to put together a list of websites most valuable for visual research, either those I’ve used and favorited in the past or some recommended by others, and I posted in Facebook groups such as the Society of British Theatre Designers (SBTD) asking for suggestions. Many thanks for the comments I received! .. I’m still working on the actual list and I will put it in a new folder Visual research in the Methods section very shortly.

For the time being I wanted first to provide a sketchy illustration as to why one shouldn’t confine one’s visual research to Google .. at least, not to the extent I’m accustomed to seeing from my undergraduate teaching. Don’t get me wrong! .. I don’t believe that Google Images can be .. or should be .. ignored! It all depends on how one uses the tool. For example, it is often my first port of call if I first want to define exactly what I’m looking for or to locate sites which are likely to give me better images and more information.

As an illustration, if I’ve really no idea what a ‘duchesse brisee’ is I can type it in and Google will very likely correct me if I’ve got the spelling wrong. That’s a great help in itself! Most of the images then displayed will give me a clear and immediate indication of what it is but also give me a wide choice of period interpretations. It may help at this point to change the search size from ‘Any’ to ‘Large’ because this often keeps the more informed sites and cuts down on the Pinterests and Flickrs. Now Google can be .. and should be .. left behind to refine one’s choice; checking the period and country of origin, and generally acquiring the kind of supporting information that sensible designers need to have! Here for example is the one I might have chosen  ..

Louis XV period duchesse brisee

The website it’s from.. ..tells me that it’s Louis XV period or mid 18th century, carved in walnut and even that it’s attributed to the maker Pierre Nogaret. A quick Google of ‘Pierre Nogaret’ shows me many other pieces of furniture of the same feel and period. Unusually doesn’t provide measurements in this particular case, but many other antiques or restoration sites do for similar pieces. Here Google repeatedly offers an invaluable ‘means’ ..but not the ‘end’.

Or to take another example, if I want specific information on what a tenement dwelling in New York looked like in the 1890s I might also try Google first just for fun. In this case, because typing ‘1890 New York tenement’ could bring up too many irrelevant results it may be better to choose the ‘Advanced’ search option and type one’s search words in the ‘all words’ box. When I did this I was presented with this image from someone’s Flickr page, which looks pretty authentic and is entitled ‘New York tenement 1890’, but as often with Flickr or Pinterest there’s no other information and no indication of source so that I can verify that it’s authentic! For the serious designer this is a rather ‘blind alley’ and therefore a waste of time.

photo from Jacob Riis 'How the Other Half Lives' first published 1890

What one needs to do is either scroll down to see whether the image appears again from a more ‘official’ source in which case there is likely to be more information about it or, failing that, click on the thumbnail and use the ‘Search by image’ option in the window that appears to find other sources. Luckily this image appears on a number of reliable sites such as the Smithsonian, or Wikipedia and further clicking on any of these will reveal the fact that the photo comes from a priceless social document How the Other Half Lives published in 1890 by the American journalist Jacob A Riis (although initially the photos were reproduced either as line drawings or halftone and wouldn’t have had the impact they have today).

photo from Jacob Riis 'How the Other Half Lives' published 1890

The point I am making is that someone intent on the ‘fast-food’ method might not even discover that, or the wealth of other relevant photos from Jacob A Riis that might not fall within the search terms used. Sure .. Google, Flickr or Pinterest will deliver instant results which can be effortlessly collected. It’s so easy to ‘click and save’ that even the thought of having to halt one’s happy gathering in order to check and document weighs curiously heavy!

The way we used to work as theatre designers before the establishment of the Internet could be admittedly arduous at times .. we had to go to libraries! We had to first search through catalogues arranged by subject or browse the shelves to locate books that might be helpful. If we found images we wanted to ‘keep’ we would have to take them down to the photocopier .. often just black&white, if there even was one and if it was working! But that meant that we had to become very focused and selective in our responses to images and the choice of them! We had to make conscious notes of where we found things, rather than trusting a computer to save that info ..which meant we were accustomed to reading and digesting it first! The books we found the images in would usually tell us all we needed to know about them and suggest yet other sources in their bibliographies. More often than not, writers were both circumspect and thorough when it came to the printed word! All this could be time-consuming, but on the other hand we could assess the quality and relevance of a book in mere seconds, just by flicking through it .. try doing that with a website!

Jacob A Riss understood not only the value but the necessity of ‘hard graft’ .. as a humanitarian, a pioneering journalist and a documentary photographer he was essentially optimistic, driven and persistent! Any serious designer, especially for theatre/film/television, has to operate in much the same way as an investigative journalist like Riss .. leaving few stones unturned. The problem with the Internet is that there are far too many pebbles!

New Blades 2015

For another year running I was so thankful that I didn’t miss the single, ever-so-brief chance last Thursday 11th to see New Blades 2015 the annual model makers recruitment fair at the Holborn Studios in London. In actual fact this was amazingly the 23rd year running and this unique event is organised each year by 4D modelshop on behalf of the colleges, featuring the work of graduating students from model making or special effects courses throughout the UK ( go to the end for more info on the colleges and courses ).

I have rather ambivalent feelings towards the terms ‘model’ and even more so ‘model maker’. Personally I cringe inwardly when I’m referred to as a ‘model maker’ because I feel it instantly reduces me to a fraction of what I am or what I’m involved with .. and judging by the quality, depth and variety of much of the work on show at New Blades 2015 I think the graduates deserve to feel the same! But however much I might dislike the term because of how little it’s understood ..seeing the show makes me very proud to be considered a ‘model maker’ too!

I’ve tried to include photos here of the work that most impressed or interested me this year, but I’ve also included work from past years which I felt was indicative of New Blades as a whole. Unfortunately, since there are no catalogues or online records of the exhibits, I was limited in the choice of photos and only had the names of the exhibitors, but no work titles or other info..

Thomas Hughes, New Blades 2015

From this year’s show above work from Thomas Hughes and below from Alex Brooker

Alex Brooker, New Blades 2015

This is not really a ‘review’ of New Blades 2015, just some thoughts on what I saw and on the regular institution the show has become over the years, because I feel that something so special deserves wider attention. The students, their tutors, the colleges and the organisers could do with more feedback, in spite of the show being very well attended during the brief time it was on.

But wider publicity is more for the benefit of the public than the contributors. There is work here that would not be seen anywhere else .. at least not so close and personal. Each year the chance comes along to focus on the type of painstaking, practical work that contributes so much to our media experiences .. if actors are venerated, almost worshipped by some, for igniting our imaginations why not the objects created too?

Imogen Nagle, New Blades 2015. Tiger mask

Also from this year above from Imogen Nagle and below from David Patterson

David Patterson, New Blades 2015

This is a great deal more than a ‘model making’ show .. it is a roller-coaster ride through some of the finest, most entertaining, most inspiring examples of physical making! It is a show about passion, dedication .. and breathtaking skill! At times it’s very difficult to connect the works on view with the young, hopeful people standing next to them during the ‘Industry Night’. The quality of many of the objects suggests more years of experience .. many years of practise and an ‘old school’ attention to detail. What comes across from the show as a whole is that the passion and dedication are so obviously shared by everyone involved with it .. the organisers, the tutors, the industry professionals and the commercial sponsors.

How can this rather diminutive word ‘model’ begin to do justice to the serious quality and vast range of the work produced. In this context the word has to embrace prosthetics, costumes, ‘cosplay’ artifacts, theatre and film props, puppets, animation sets, automatons, animatronics, character portraiture, creature design, architectural models, product design, museum and exhibition displays, sculpture, fine engineering and bespoke furniture.

Stephanie Bolduc, New Blades 2015. Still from 'Manoman'

Above still from Stephanie Bolduc’s short film ‘Manoman’ and below work from Alexandra Poulson, both from this year’s show

Alexandra Poulson, New Blades 2015

Below work from Matthew Cooper 2014

Matthew Cooper, New Blades 2014

Joanne Harvey, New Blades 2014

Above costume work from Joanne Harvey 2014 and below Ollie Knights from the same year

Ollie Knights, New Blades 2014

Perhaps the general tag of ‘model’ is not so bad in some respects though .. it is like a little signpost pointing to the ‘hands-on’, the physical and practical. Unlike some Degree shows objects are always centre-stage here, and partly because of that each show is packed with immediate focuses of interest .. but never feels cluttered!

'please touch' New Blades 2013

The roller-coaster experience may be a little unkind to the architectural or product models exhibited .. I always feel a bit sorry for them! They need a quiet zone of contemplation. They are often beautifully made, faultless, and they certainly have their devotees amongst the audience .. I would say the same for the custom vehicles .. but they’re not so likely to get the ‘popular wow’ vote.

Henry Welch, New Blades 2015

Above Henry Welch from this year and below Petre Craciun from 2014

Petre Craciun, New Blades 2014

Below Ollie Knights 2014

Ollie Knights, New Blades 2014

There are however prizes awarded in a number of categories, including ‘Best Architectural Model’ ( awarded in 2014 to Petre Craciun, above ). We all like being acknowledged ourselves and it’s difficult not to be moved when we witness the acknowledgement of someone we believe deserves it, but I feel that the prize-givings are more just a part of the entertainment. With so much variety, so much choice .. it can never be completely ‘fair’ .. I’d estimate a good 25% of the achievements in New Blades deserve the same accolade each year!

Speaking of choice .. in terms of subjects and treatments I’m guessing that students don’t have a completely free choice as to where or how to focus their efforts. If they want to get work these choices are conditioned by the market and tutors would be failing the students if they didn’t equip them to satisfy it and guide them towards it. So bearing this mind there’s always a surprising measure of individuality and innovation .. I’m just not sure that I want to see another Incredible Hulk, Elephant Man or Dobby the House Elf. I feel that no matter what skill or sensitivity is shown it’s getting hard to remain inspired by them.

Skilled makers don’t necessarily have to be innovators, or have great or original ideas, but in New Blades 2015 as in previous years there was no shortage of ‘special’!

Thomas Hughes, New Blades 2015

Above another piece from Thomas Hughes this year and below from ‘S.B’ 2013

S.B, New Blades 2013

Below another piece this year from Imogen Nagle, ‘Herman the merman’

Imogen Nagle, New Blades 2015 'Herman the merman'

The show also offers the unique opportunity to learn something about the making processes. As one comes to expect from design/practical Degree shows there are many portfolios to browse through which include detailed records of the designing and making process. What distinguishes New Blades in this respect compared to other Degree shows I visit is that many of the students really do take this aspect of ‘record keeping’ seriously .. as an integral part of their work. Often the work-in-progress photos are not merely snapshots, but carefully balanced and crafted works in themselves! I think this reflects the increasing importance of Internet presence, but also perhaps the increasing popularity of ‘making ofs’ as part of the entertainment.

Imogen Nagle, New Blades 2015 'Herman the merman' sculpt

Above ‘Herman’ sculpt from Imogen Nagle and below the ‘space bulldog’ maquette in progress from Thomas Hughes

Thomas Hughes, New Blades 2015. Space bulldog maquette in progress

But I feel one of the most important inspirations from this exhibition within the current climate is that much of the best work emphasizes the value of ‘fusion’ .. the discerning use of digital help and the perfect fusion of traditional hand-work and machine-enabled. Faced nowadays with a greatly expanded toolbox, ‘model-makers’ have to become expert ‘choosers’.

Rujie Li, New Blades 2015

Also from this year above Rujie Li and below Jack White

Jack White, New Blades 2015

It may be wrong to take perfection or absolute realism as benchmarks for judging the physical work .. one has to accept that if the work is destined for the screen it could undergo further transformation. Considering the fusion of practical and digital methods currently prevailing it may not make economic sense for a physical object to contain every nuance .. it may be quicker, easier and cheaper to add refinements digitally. On the other hand I’m guessing that the students are nevertheless encouraged to put as much as possible into the physical rendition. I was very glad that the exhibition gave the physical objects centre-stage, and that there seemed to be very few monitors or laptops around!

This year’s students haven’t exactly been ‘quick off the mark’ in getting their portfolios online, part of the reason why I’ve used examples from past years as much as from the present to illustrate the range and standards achieved. If you like what you see, you can see more work from this year’s or previous exhibitions at

.. and go to the 4D modelshop website from May onwards next year to see when the next New Blades will take place.

There’s only one single and major fault with this show .. that it’s not on for longer, at least long enough for more of the public at large to appreciate what it offers! It’s always brief, but this year was extremely so. It’s a big ask in London though! It must cost a lot to stage it even for a couple of days and all money made goes towards the costs.

University of Hertfordshire, Character and creative effects

Above work from the University of Hertfordshire website

The colleges and courses

If you’re not a film/tv industry insider you may struggle to understand what is meant by ‘visual effects’ as opposed to ‘special effects’ .. and it’s even a little more complicated when it comes to courses! Course options are changing in accordance with constantly evolving territories. For example University of Hertfordshire offers three ‘Model Design’ BA choices .. ‘Character and Creative Effects’, ‘Model Effects’ and ‘Special Effects’. Arts University Bournemouth offers one comprehensive BA in ‘Modelmaking’. University of Bolton runs a BDes in ‘Special Effects for Film & TV’. University for the Creative Arts entitles their BA ‘Creative Arts for Theatre and Film’ and City of Glasgow College offers an HND in ‘3D Design: Model Making for the Creative Industries’.



Working with epoxy resin

I’ve started working with epoxy resin and have put quite a few pages of useful information under casting in the Materials section, together with the write-up of a recent test. I’ve copied them here in full..

Definition and general properties

Epoxies tend to be stronger than other resins, certainly much less brittle on their own than polyester .. in other words, they have very good flexural strength! They come as two parts which are commonly mixed in ratios ranging 2:1-4:1 resin to hardener by weight. Also compared to others, epoxy resin generally has a very long pot-life (working time) i.e. even a ‘fast’ epoxy resin will still give c.15mins working time before it starts gelling whereas a regular/slow can take 100mins or more (the average would seem to be 40mins). A ‘fast’ epoxy may be demouldable in 8hrs and sandable after 12-18 hrs whereas a ‘slow’ may need 30hrs before it can be removed from the mould. Full cure generally takes 5-7 days.

The density is on average like polyester resin SG 1.1 (the weight in grams of 1 cubic centimetre of mixed resin). Viscosity is generally higher than other resins (i.e. its usually a thicker liquid) with an mPas of 1000-1400 being considered ‘medium’ for epoxy. The thinnest I’ve come across so far has a viscosity of 600 mPas .. compare this with polyurethane resins which can be as little as 50 mPas.

They are also much more adhesive (hence their modification as epoxy glues). They are usually more transparent and cleaner looking than many general-purpose polyesters. However, water-clear epoxies specifically for solid casting are not common, presumably due to the high risk of excessive heat build-up .. the water-clear epoxies commonly available are almost always just for laminating or coating. There are a great many varieties, but most share a relatively long pot-life and cure time compared to other resins. Epoxy resin is just as commonly used as polyester for the binding resin in fiberglass work but because epoxy is more expensive this applies more to industrial applications.

‘The chemistry of epoxies and the range of commercially available variations allows cure polymers to be produced with a very broad range of properties. In general, epoxies are known for their excellent adhesion, chemical and heat resistance, good-to-excellent mechanical properties and very good electrical insulating properties.’ Wiki ‘Epoxy’

In terms of working conditions, epoxy is almost odourless compared to polyester resins.. though this shouldn’t fool anyone into thinking that good ventilation is not as important!

Often resins marketed for sculpture purposes are tagged as ‘not Lloyds approved’ meaning they may not have the structural integrity or moisture resistance necessary for boat-building but are fine for sculpture. This works to advantage because they are often cheaper.

Uncured epoxy can be cleaned up with acetone, cellulose thinners or methylated spirit.

You may see the term ‘infusion resin’ applied to standard laminating resin. This simply means that the resin is of a suitably low viscosity to be used for vacuum infusion .. which is a process whereby instead of being brushed on resin is sucked into the reinforcement material under pressure. This eliminates the air pockets which may occur using brush-on methods and ensures stronger fibreglass.

EL2 laminating epoxy resin from Easycomposites


Advantages of using it

Because of its flexural strength it is ideal for the laminating or casting of load-bearing forms or those which will be subjected to stress. Many epoxies also have enhanced moisture or chemical resistance making them preferable for exterior sculpture (but see below re. UV exposure).

Because of epoxy’s adhesive qualities, good ‘wetting’ properties, the relatively long pot-life before it starts gelling and its toughness.. it is considered ideal for coating or laminating. It is a common constituent in special paint finishes; for the home-practitioner the longer working time makes it ideal if you want to mix your own resin paints.

Re. the above qualities, the resin can just be used as an adhesive and it has very good gap-filling properties when combined with fillers. Most epoxies will bond wood, metal and even quite a few plastics. For example it will usually bond with any plastic affected by acetone. Epoxy will bond well to cured polyester fiberglass but polyester won’t return the favour on epoxy. As with anything, if you’re serious, and you want to learn properly for yourself a test first. Epoxy is more adhesive than polyester or polyurethane because it is able to form bonds with the substrate (the material being glued) at atomic level whereas other resins can only bond mechanically i.e. by gripping tightly.

Epoxies do not attack polystyrene, so may be an ideal choice for coating polystyrene or styrofoam forms.

Epoxy will take a variety of fillers, basically anything inert and free of moisture.. talc, Fillite, marble dust, metal powders etc. I’ve read that powdered/dried ‘ball clay’ mixed into epoxy will even make a good, clay-like putty. Because of the generous working-time it’s practical to mix resin with hardener first before adding filler .. this is usually advised with epoxy. This has an advantage because it means that the consistency can be judged as one’s adding.

Like both polyester or polyurethane resin, most of the epoxy resins available for home use need no special pre-warming in order to cure when mixed and will do so at normal room temperature i.e. c. 20C. Most however allow ‘post curing’, that is, accelerating the cure by heating at a moderate temperature for a number of hours.

The resin component has a much longer shelf life compared to other resins .. sometimes up to 3 years, although the manufacturers are usually bound to define it as 1 year. This is partly because the hardener part is more active, with a shorter shelf life. Apparently though, there are stories of unopened epoxies being discovered after decades and working ok!

Fully cured epoxy can be softened by heating to a temperature over 200F i.e. with a heat gun, but this should only be done in a well ventilated room.


As one should expect, one pays for the advantage of a long pot-life by having to wait much longer for the cure and, as mentioned, with some it could be a couple of days before the cast can be safely demoulded. It also means that epoxy is not so suitable for ‘slush’ or ‘rotocasting’ methods especially by hand, unless you want to sit there doing it for more than an hour!

The resin itself doesn’t present quite the same health & safety issues as polyester and is considered little more than a possible irritant to eyes and skin. However, the hardener part is a different matter! It is classed as ‘corrosive’ and could be very unpleasant if it gets on the skin. It is also harmful by inhalation. Precautions need to be taken against skin contact and, as with all resins, good ventilation is essential!

In price epoxy resins average a little more expensive than polyurethanes, but a lot more than the cheapest polyesters (see example prices below).

Epoxy resins are pretty unforgiving when the mix is even a little bit out, for example the Technical Data Sheet for DX020 from Tomps states ‘The components should be measured to an accuracy of 2% or better’ .. in other words, more than 98% accurate! This can only be done by weight .. not recommended by volume! It also means that it’s not a good idea to measure out portions in separate cups and then decant one into the other when ready, because even the slight amount adhering to the cup could make a difference. Mixing needs to be obsessively thorough! .. not forgetting the sides or the bottom of the mixing vessel. When mixing silicone rubber thoroughly I usually recommend spending at least 3mins to be sure, and I would say the same for epoxy. Often it’s wise to transfer a thoroughly mixed batch into another vessel and mix again to avoid unmixed residues on the sides or bottom of the cup.

There are often warnings accompanying epoxy resins that thick layers .. especially massed volumes.. will become very hot during cure, causing increased shrinkage. Many epoxies are labelled as ‘laminating resin’ which often (though not always) means that they are not suitable for cast volumes. I’ve read the advice that, if smoke starts rising from curing epoxy ‘it’s likely that the epoxy is damaged and should be replaced’ .. and I would add that it should be swiftly but calmly taken outside! To avoid this happening, large and solid castings therefore need to be done in stages which, because of the long pot-life, can become a lengthy process! Although one presumably doesn’t have to wait each time until the layer is cured, I’m assuming it makes sense to wait until it’s at least cooled down but even this can take a while! West System recommends layers of not more than 12mm when working with their epoxies. There is usually no danger of excessive heat build-up or shrinkage when laminating thin layers with a reinforcement in the standard way.

Even the low viscosity epoxy types are considerably thicker than some polyurethane casting resins, so they are not a good choice for intricate castings. On the other hand, if the moulds are 1-piece and open the long pot-life gives a lot of time to pour and coax the resin to fill an involved shape. But partly as a result of higher viscosity, many small air bubbles are generated while mixing and these are persistent! Usually the extended pot-life allows taking the time to deal with these i.e. by skimming away, or passing a hair-dryer or heat gun over the top surface which will eliminate many. Bear in mind though that any heat applied will reduce the pot-life, though this will not be a dramatic reduction. Pouring the resin into an enclosed mould needs to be done very slowly and carefully!

Another problem involving bubbles occurs when using epoxy for coating a porous surface such as foam or wood. As the epoxy heats itself while curing this will expand the air underneath it, forcing it out to form bubbles in the resin. The only solution is to make sure that the original surface is completely sealed first. One way is to prime the surface first with a very thin coat of resin and let this set firm before applying a thicker coat.

Epoxies are particularly susceptible to prolonged UV exposure. For this reason when used in boat-building they are more often employed for the inner structure rather than the outer surface. Sunlight doesn’t just discolour epoxy, it degrades it. Deterioration due to UV is known as ‘chalk out’ in the case of epoxy paints or coatings. The usual fix is to coat with a ‘2k’ UV resistant varnish although I’ve read that this doesn’t solve the problem completely.

Although epoxy is ideal for fibreglassing there are some notable differences in method compared to polyester work. The major one is .. with the polyester resin I use for fibreglassing work (Tiranti’s GP) it doesn’t matter if one layer has been left to become fully hard before the next is applied. The second layer will bond firmly to the first, and I’ve certainly never experienced any instances of layers ‘delaminating’, that is, coming apart because of time intervals. Most of the guidance when using epoxy suggests the contrary. Layers should be applied while the first layer is still in the so-called ‘green stage’, meaning that although it may feel touch-dry it should still be possible to make an impression with the fingernail. Any later and the fresh epoxy will no longer be able to chemically link with it. In this event the hard epoxy surface needs to be sanded then dusted/cleaned, to at least ensure a good mechanical bond. Another difference is that whereas with polyester resin one can compensate for certain conditions simply by varying the catalyst dosage i.e. according to the volume of resin being used, the addition of fillers or the ambient workplace temperature .. with epoxy this is not possible because resin and hardener must always be mixed according to the set ratio. The only ways to compensate are either to have the choice of either a slower or faster hardener on hand to use, or to apply external heat while mixing or curing.

Working life

Here are my test notes from 25/5/2015, testing Polyfibre’s EL68 resin with EHA57 hardener (not the one imaged above). The mix ratio was an easy one.. 2:1 resin/hardener.

The product is +14 months old (bought March 2014 and unopened). A little, approx. 1g, poured in plastic cup then tiny amount of green powder pigment mixed in.. appearing to mix well. Topped up to 20g resin, then colour thoroughly mixed in again. Profuse creation of air bubbles! 10g hardener added and mixed together. Material is colourless compared to my usual GP polyester resin.. clear, though not quite water-clear. No noticeable smell. I left most of the resin left in the cup but I trickled some onto a polypropylene sheet to see how the resin would cure in small/thin amounts and to test whether polypropylene would be a good ‘releasing’ base.

epoxy resin pigment/mixing test May 2015

Surprisingly, no evidence of heat reaction for a long time, very mild heat felt from the bottom of the cup at 35mins. After 45mins mix is much thicker but may still be spreadable .. stronger heat from cup but by no means excessive. After 60mins firm gel in cup but the thin ‘spills’ on polypropylene sheet are still sticky like clear ‘honey’. After 90mins almost fingernail hard at cup centre but still soft at edges and flat spills are still unchanged.

epoxy resin cured enough to 'demould' from cup

Returned to at 7.30 a.m. the next morning (16hrs). Both pot and pools touch-dry and hard, no surface tackiness even on thin residue lining the mixing cup. On demoulding the cup contents the resin parted easily and cleanly, with complete surface reproduction, though it gripped noticeably more than polyurethane or polyester. There was a small area of tackiness around the rim of the cast piece (bottom of the cup) which could be due to not mixing 100% thoroughly .. even though I was consciously much more thorough than I normally am when mixing PU or polyester! The thin residue lining the cup above the mass came away intact with the casting and was strong but very flexible, no brittleness. The pigment colour was completely even with no grain.

The ‘spills’ on the polypropylene sheet were touch-hard and firm, with a beautifully smooth, polished-look surface showing no sign of pitting or clouding. But they would not detach even on extreme flexing of the sheet, remaining flexible. An attempt to prise up a small area with the tip of a scalpel blade merely curled and damaged the resin though it did detach. For the moment the resin is effectively stuck fast and I will have to wait longer before I try again.

After another day the resin ‘spills’ were no easier to detach. By getting a blade underneath the pieces could be popped off, but not easily. It shows the adhesive strength of epoxy because even superglue fails to cling as well to polypropylene! Epoxy is supposed not to be able to establish a bond though with plastics which are impervious to acetone, of which polypropylene is one. If I ever use polypropylene as a ‘releasing’ base for epoxy work I will have to remember to spray with a release agent i.e. pva (polyvinyl alcohol) or possibly hairspray (as I’ve heard).

excessive build-up of air bubbles in epoxy resin

Apart from this the two other most significant results were the lack of expected heat from the resin mass .. although small the piece is 2cm thick and av. 4.7cm across .. and the bubbles! I purposely left them unattended to in the cup to see whether they would pop of their own accord, which they didn’t. On the plus side though, they all rose to the surface. There were bubbles initially in the ‘spills’ but most of these could be forced out by ‘tamping’ i.e. jolting or shaking the sheet. I had to pop the remaining few with a cocktail stick.

As for the lack of heat, it may be due to the hardener part being a little past its shelf-life although the resin part is relatively inert and should be fine. Unfortunately I can’t check the results against technical guidance or MSDS since Polyfibre doesn’t provide either!

A little bit of history

‘Credit for the first synthesis of bisphenol-A-based epoxy resins is shared by Dr. Pierre Castan of Switzerland and Dr. S.O. Greenlee of the United States in 1936’ Wiki ‘Epoxy’

What was it about 1936? This was the same year that the first proper patents for both glass fibre and polyester resin were independently recorded!

Additional info

Colouring epoxy resin

Like other resins the general rule is that one can add up to 10% by weight if using a powder pigment, up to 5% if using any other liquid colourant. Similarly, water-based colourants are out .. but usually oil or spirit-based are ok, plus of course specially formulated resin colourants which are usually pre-mixed with a small amount of resin. In the test detailed above the resin ‘wetted’ standard powder pigment very well .. all of it dissolved very easily, there was no frothing of the resin, no graininess and no sinking of the pigment. For more info see this article;

Dealing with the bubbles

Careful heating with hair-dryer or heat gun over the open surface of the mixed or curing resin. The heat source should not be too close, in the case of a heat gun about 30cm away. Another method is to put some methylated spirit in a small ‘mistifier’ bottle and spray a fine mist on the surface. The alcohol doesn’t adversely affect the resin and evaporates quickly, but acts long enough to reduce the surface tension and pop the air bubbles.

Methods of thinning

Thinning the resin itself could help a lot in the elimination of air bubbles when mixing. It can also help the resin to better impregnate a surface if the resin is being used as a coating, or to make it flow better into a complicated form. Apparently there are a number of ways of doing it, though I can’t vouch for them because I haven’t tried them myself. One method is to heat the resin! Epoxy changes viscosity, becoming thinner when it’s warmed. The recommended method is to heat up the two parts separately (whichever way you prefer .. but standing the cups in hot water would probably be best) and then mix them. As always, bear in mind that heating will reduce the working time and accelerate the cure. Note also that if using two cups for dosing the resin initially, once warmed both should be decanted into a third cup for mixing together to maintain the ratio. I noted from one info source that the temp should not exceed 115F (46C). I wouldn’t imagine that it’s a very good idea to heat it if you’re pouring a massed volume anyway though, because it increases the risk of the resin overheating with its own exotherm .. if one actually does have to be as careful as they say!

Apparently another method is either to add acetone (not more than 10% by volume) or methylated spirits (US ‘denatured alcohol’) at 15-20%. Adding solvent will affect the strength of the cured resin, but this may not matter too much with small castings. See this article for more informed advice:

Cold casting with metal powder

Works well with epoxy and the surface is not too hard to be successfully ‘cut back’ or buffed with steel wool. Apparently olive oil can be used to give an even patina.


What it costs and where to get it

Prices are dated, and adjusted to include VAT

EL68 resin/EHA57 hardener £26.04 per 1.5kg (1kg resin, 500g hardener. Specialplasters 5/2015) Specialplasters describes this as ‘a low viscosity epoxy resin for laminating and casting’. Mix ratio 2:1 resin/hardener by weight. Manufactured by Polyfibre. The hardener is described as ‘fast curing’; EL68 is a Bisphenol F type epoxy (Bisphenol F epoxies generally have a lower viscosity and greater chemical resistance once cured). Polyfibre do not currently offer an MSDS or further tech data on their website!

EL2 Laminating Epoxy £20.10 per 1kg (770g resin, 230g hardener), £65.93 per 5kg (Easycomposites 5/2015). A choice of hardener is offered; fast (12-17mins pot-life) or slow (95-115mins). Mix ratio 100:30 resin/hardener; medium viscosity when combined 1000-1400 mpas; clear; SG when combined 1.05-1.15. Easycomposites advises that applying it over 1mm thick in one pour could result in too much heat build-up unless the slow hardener is used in which case 5mm should be possible.

DX020 £29.10 per 1.5kg (1kg resin, 500g hardener.Tomps 5/2015) Also described as a low viscosity laminating and casting resin. Pot-life 75-90mins; demould time 2hrs; Shore D 80-90 hardness after 5days cure. Manufactured by Atlas Polymers.

Epovoss Glosscoat £35.86 per 1kg (Tiranti 5/2015) from the website page: ‘A general purpose clear epoxy resin for casting, embedding, cold enameling and coating. The resin is very slightly straw coloured, but this is virtually unnoticeable in coating applications. Epoxy resin cures with a nontacky surface, is self levelling, nonshrinking and will adhere to most surfaces. Polyester Pigments may be used with this resin (5% maximum), and also a whole range of fillers.’ Mixing ratio 100:40 resin/hardener; pot-life 30mins; SG c.1.1; demould 12hrs.

Further info sources

A leading supplier of high-grade marine epoxies. There is a lot of technical information and guidance on the site, almost all of it dealing with boat-building work, but even some of that is useful, i.e. if you want some expert advice on methods of coating with epoxy and getting a smooth, bubble-free surface have a look at this

A quick guide to soldering brass

materials and tools for soldering

I’ve finally managed to update my guide to soldering in the Methods section and I’ve now included photos. Some of these come from my book Model-making: Materials and Methods from 2008 and were taken by Astrid Baerndal. This guide focuses on soldering small constructions, rather than the more common electrical soldering which almost all of the info you’ll find on the subject deals with. As you will see, ‘constructional’ soldering involves some differences in method; the materials are different and quite often stronger tools are needed. For the moment I’ve confined this guide to simple soldering ‘on the flat’ and more advanced methods of assembling 3D constructions will follow.

What is soldering useful for?

For model forms which are too thin to make to proper scale in other materials such as card, wood or plastic .. for example metal bed frames or railings. Occasionally, for bendable metal armatures ..e.g. for figures or trees .. allowing for some careful repositioning. Soldering does not give nearly as strong a bond as welding, and the joints can’t be put under much stress, but there is no reason why properly soldered items shouldn’t last for a long time if cared for.

Most of my teaching work focuses on making 1:25 scale models .. so 0.8mm round brass rod is a convenient thickness for representing slender railings or special items such as the brass bed frame shown below. This bed frame is mainly 0.8mm, but with 1mm at the corners. Most of the 40W soldering irons I’ve tried have had just enough heat output to manage thicker rods .. up to 2mm, the size of standard scaffolding at 1:25 scale.

soldered brass bed frame on drawing

What metals can be soldered?

One of the reasons why I’m updating my soldering info now is that I’ve discovered some new things which call into question what I’ve always been told .. that brass is the only easy option, or at least the most reliable one. I still agree that brass could be the most consistent and the least complicated .. followed by copper, if it’s thin. These are also the two most available from craft or hobby shops in wire, rod or thin sheet form. But I have found ‘gold’ paperclips  to be just as easy and I always assumed this was due to a brass coating I’m not so sure that’s the reason. For example I recently tried silver paperclips, with the same results! I’m looking into other possibilities at the moment and I will update the info here once I’m sure of it. I also found that the ‘welded wire mesh’ commonly available nowadays solders very well .. when I know I tried it years ago with little success! This common mesh is galvanised steel i.e. steel which has been coated with zinc. Apparently paperclips are also made of galvanised steel as a rule, so there may be a connection here.

The simple answer for the moment is that brass is guaranteed to work well, it’s available and reasonably cheap. Other metals such as aluminium or regular steel can be soldered, but require special solder and flux and may need stronger equipment. But if you really want to know what else is possible, just give it a go ..and let me know what you find out!

How soldering works

The metal parts to be joined are heated with the tip of the iron so that they will be hot enough to melt the soft metal solder applied to them. It is important for a lasting joint that the metal itself melts the solder in this way rather than melting solder onto the iron tip and transferring to the joint because this will achieve only a very weak attachment. One could think of it as a form of ‘hot-melt’ gluing, but using a low-melt metal in place of glue sticks and where the material itself has to melt the glue.

soldering in progress

In the photo above I’ve placed the tip of the soldering iron so that it’s touching both pieces of brass rod and as close to the joint as possible. Once this area is hot enough the end of the solder wire just needs to be touched into the joint and a little of it should instantly melt. The iron should be kept in place just long enough to allow the now liquid solder to infiltrate the joint properly .. i.e. not just covering the top but also running to the other side.

If you’re familiar with ‘constructional’ soldering you may ask why there’s something important missing from the above setup .. there’s no sign of any flux applied to the joint. This was purely a demonstration setup and the iron wasn’t even on .. I wanted the joints and the position of the soldering tip to show as clearly as possible. I’ll explain the importance of flux a little further on.

What is needed to do it?

See the end section for recommendations on specific makes, suppliers and price-guidance for the following list:

A soldering iron of at least 30W strength .. 40W better! .. preferably with a flat ‘chisel’ like tip, known as the bit. This means one can press down for maximum contact with the metal surfaces. However, the majority of soldering irons available are supplied with round ‘pencil’ like bits. As some of the older photos here will show, a standard ‘pencil’ bit will work if the iron has a strong enough wattage to generate enough heat, but over the years I’ve found that a flat bit can help a lot more especially when soldering thicker rods! You will also find that the majority of soldering irons on offer are too weak to tackle metal of any thickness beyond a small fraction of a millimetre .. because most are designed for soldering fine circuit connections. These don’t need to be strong .. they’re commonly around 18-25W. A higher wattage such as 40W doesn’t necessarily mean that the iron will reach higher temperatures .. just that it will have more strength to sustain the heat needed for longer. This is important since thicker pieces of metal will conduct the heat away very quickly.

All this makes the search for the right soldering iron and the price options just a little more involved .. but unfortunately there are further things to look out for. Look at the three irons compared below:

At the top is my old Draper model K40P .. 40W/240V .. which came with a ‘chisel’ bit and has worked very reliably for many years now. Notice the screw head at the end of the shaft which means that the soldering bit can be easily extended or removed just by loosening it. The bit supplied with the Draper is about twice as long as what you can see sticking out, which means that there’s plenty to extend as it wears away. Underneath is the iron from the ‘Parkside Soldering Station’, a cheap offer from Lidl a couple of years ago and a peculiar 48W! This iron works reasonably well in terms of heat output and the integrated stand makes it comfortable to use .. but .. the soldering bit is the ‘screw in’ type, and very short .. so short that it’s impossible to press the bit flat against metal without the shaft getting in the way. Unfortunately a rather careless design .. making it useless if you need any control! The third iron shown is a 40W/220V from Silverline, who make fairly inexpensive but often reliable tools. This comes with a ‘pencil’ bit, which is not the best to have .. but the heat output is good, the shaft is slender, and the bit supplied can be extended (the locking screw is not visible in this photo) for more control. This has worked reasonably well so far during our soldering workshops.

soldering bits compared

The type below could also be a good option .. although angled bits are not very common. I found this ‘unbranded’ iron in a £-shop and it has worked very well for a number of years. Perhaps it goes without saying though .. one does need to be extra cautious when using cheap, unbranded electrical goods! Really, if you don’t know how to test the electrical safety or know someone who can, it’s safer to leave well alone!

unbranded soldering iron from a pound-shop

To sum up .. get a recognised brand 40W iron with a relatively slender shaft, a ‘chisel’ bit and/or the option of changing easily by means of a simple screw-locking mechanism, and you can’t go wrong! If possible check that the bit provided is long enough to be extended if need be.

A stand (sometimes supplied with the iron) is essential, both to hold the hot point off the work surface when not in use and to secure the tool in one position on the table. Unfortunately the flimsy sheet-metal ‘stands’ most often supplied never manage the latter! There seems to have been a fairly universal agreement that soldering irons should all have just a little over 1.3 metres of rather inflexible cord . This is not long enough to allow the soldering iron to stay on a work-table without some pull from the cord, unless one has a handy power socket ‘kitchen style’ at worktop height. In short .. the iron will move around a lot, independent of one’s awareness or control, which is worrying considering it can inflict a lot of pain! There’s a cheap solution, shown below, which is to tape whatever ‘stand’ you have to the table. Here I’ve improvised a perfectly adequate stand out of welded wire mesh.

improvised soldering iron stand made from welded wire mesh

Or a more elegant solution is to buy a separate stand unit. This one below is from Antex and costs around £6 .. more on prices later. These stands are weighted, and usually have a sponge attached which must be dampened if used for wiping the iron while working.

Antex soldering iron stand

Solder A soft metal alloy wire which melts on contact with heat to form the ‘glue’ which makes the bond. Up to recent times the standard type was 60%tin-40%lead but now there are many lead-free alloys available. Also common now are ‘multicore’ solders with built-in flux. But I have to say honestly that I’ve had consistently better results over the years using an old-fashioned tin/lead solder and a separate flux.

Flux A liquid or paste which is applied to the joint just prior to soldering and which assists the solder to fuse properly with the metal by preventing the metal surface from oxidising. The flux evaporates as soon as the metal gets hot.

Steel wool or fine emery paper/cloth to clean the metal before soldering. It will be easier to wipe rods clean with fine-gauge steel wool but emery or ‘wet/dry’ paper will also work.

A damp sponge, steel wool or metal files to clean the soldering bit while working. This needs to be done once the iron is hot, but it is not enough just to do it once at the beginning of a session. The hot bit of the iron will blacken again within a minute, so to prevent build-up of this oxidation the cleaning needs to be repeated at least each time the iron is picked up again. This has nothing to do with cleanliness! .. a thick layer of oxidation will prevent much of the heat transferring from the bit to the brass.

Kapa-line foamboard or heavy card on which to mount the template drawing

Caution note: Kapa-line (polyurethane) foamboard is suggested because it is a perfect insulator (will not conduct heat away from the metal) and polyurethane foam resists heat to an extent. Standard (polystyrene) foamboard is not suitable .. this melts too easily! If soldering is done properly the paper covering on the Kapa-line foamboard will scorch but there is little danger of fire or burning of the foam. However, proper care must always be taken! Over almost 10 years of conducting workshops we have experienced nothing more than routine paper scorching .. but this is partly because we, and the people taking part, have always been vigilant! Soldering irons must never be left on when not in use for long periods and must be kept well away from flammable materials.

Spraymount for mounting the drawn template onto the foamboard. I normally use the permanent ‘PhotoMount’ version from 3M.

Masking tape for fixing cut metal to template. The tape will normally resist the heat sufficiently to secure pieces while soldering but the glue softens and in cases where extra time is taken or areas redone these fixings can become very loose and may need to be replaced. Understandably ‘Sellotape’ is not an option because it will melt!

Scalpel (adequate to nick a groove thin brass) or hacksaw for thicker rods. I keep some old scalpel blades for this and I’ve found nicking/snapping brass rod up to 2mm diameter fairly easy.

Also pliers, wire snippers and metal files .. as/when needed.

A workplace with good ventilation! This is essential if you are using a traditional tin/lead solder. In addition, flux will burn off in the process and the fumes can be harmful if allowed to build up or stay around.

Detergent to thoroughly clean work afterwards. The flux component is corrosive and it will continue to eat the metal away if left.


Draw up the form to be soldered on paper ( I recommend drawing 1:10 first then reducing 40% for 1:25 if working in this small scale ). Copy this and spraymount to foamboard or flat card. This will be the soldering template. I’ve designed the one below so that I can make use of the curved parts of paper clips.

copy of drawing spraymounted to foamboard as soldering template

Clean metal thoroughly with steel wool before cutting small lengths, even if the rod is newly-bought. Brass rod is given a coating to stop it tarnishing too quickly, and this will interfere with the adhesion of the solder if it’s left on. Rubbing with a fine steel wool is the most convenient method, though ‘wet/dry’ or emery cloth will also work.

cleaning brass rod with steel wool

Cut metal pieces to fit and use thin strips of masking tape to secure them in place on the template. Metal edges must fit to touch, so that heat travels. Luckily thin brass rod is surprisingly easy to cut with a scalpel .. just by carefully rolling the blade across it to make a fine groove and then snapping! With this method one can be very precise as to where one cuts. A small metal file such as the one below will be useful for making fine adjustments to the lengths if need be.

pieces of brass being assembled on a railing template

Usually, and especially in the case of railings, quite a number of pieces are needed which have to be precisely the same length .. because most often they have to fit between two horizontals. The best method of achieving this is to make a ‘cutting jig’ .. an ‘L’ shaped piece of card or plastic which serves as a guide for the scalpel blade as shown below.

using a guide to help cutting pieces of brass the same length

Switch the iron on and allow to heat up for a few minutes. Make sure that the iron ‘bit’ (the tip that gets hot) is clean. If not, wipe on damp sponge or steel wool, or use metal file. Some model-makers recommend ‘tinning’ the iron at this point (dipping the very end of the bit in flux and then applying a little solder to it). This may help the heat-flow to the metal if there are problems, but it may not be necessary.

applying flux to a joint

I use a small, old paintbrush to put a little of the flux (whether paste or liquid) onto the joint. I prefer to do this one joint at a time, because if more are fluxed in close proximity the flux on these will evaporate as the first joint is being heated. It may not matter .. it’s just become a habit.

After applying the flux touch the soldering iron bit as near as possible next to the joint, trying to touch both (or at least more than one) of the metal parts. Hold there for a few seconds .. a good initial sign is if the flux immediately start to smoke, meaning that the brass is getting hot enough. If nothing appears to happen try adjusting the angle of the iron for better contact but don’t take the iron away! With the other hand gently touch the solder wire to the joint. A little solder should melt fairly instantly and hopefully run into the joint. Use as little as possible ..though this will take some practise! Some patience may be needed to hold the iron relentlessly in place, or fine-tune the angle, until the solder decides to melt. It’s actually very difficult to describe exactly what leads to a ‘successful’ soldered joint in every case. It has to be tried, and if something works, looks right and feels strong’ll establish a ‘feeling’ for what you did to achieve it after some trial-and-error and a lot of repetition!

soldering in progress

When all joints are done the work can be removed from the template almost immediately .. fine-gauge pieces like this will cool very quickly. The work should then be cleaned carefully ( either with warm running water, toothbrush and detergent .. or the dry method, using steel wool ) to remove remaining flux. If left on this will continue to eat away at the metal.

portion of soldered brass railing cleaned up

I was fairly happy with this result .. I’d managed to keep the bits of brass rod reasonably straight while soldering them. I did have to work on this piece a bit though, apart from thoroughly cleaning up with steel wool. It can often be very difficult to be as minimal as one would like with the solder, and a number of the joints were far too ‘swollen’ looking. Solder is so soft that it can be shaved away with the tip of a scalpel blade, or one can use needle files like the one above to remove the excess. Soldering ‘kits’ often have a desoldering pump thrown in, which is like a spring-loaded syringe. The idea is that excess solder can be quickly sucked away while it is still liquid. I’ve yet to try one of these myself ..mainly because at that point I don’t want to risk knocking the brass pieces out of alignment!

Why is brass the easiest to work with?

Brass is an alloy this case a mixture of copper and zinc. The zinc gives brass a tougher surface and more rigidity than copper, but also makes it less malleable, more brittle. Brass rod is strong enough to maintain its shape and straightness well, but soft enough to be easily cut with hand-tools. For these reasons it is one of the most available metals in a wide variety of fine-scale forms. Copper is softer and can be worked even more easily, but rods of around 1mm thickness would deform too easily and have much less structural rigidity. In addition, copper is an excellent conductor, which means that standard soldering irons would struggle to keep up with the constant heat loss from the joint area.

closeup of different soldering joints

Above is a close-up showing three common types of joint. .. spot, lap and butt..! Underneath are two small pieces of very thin ..0.1mm.. brass sheet which have been attached by melting spots of solder. To the right is the simple form which I have illustrated so far, where two straight pieces just ‘butt’ against each other. Below to the left is the strongest form of joint, where a small length of one piece runs against or ‘overlaps’ the other.


If the solder is not melting freely on contact with the heated joint or running off in little beads it can mean that either: may be the wrong kind of solder; the joint is not fluxed or there is not enough; the iron may not be hot enough yet, or strong enough for the work; the bit may need cleaning; the tip shape is not making enough contact or close enough to both pieces of metal …

If all else fails assist the heat-flow either by ‘tinning’ the iron as some recommend or touching the iron tip practically over the joint, melting solder directly on the tip to fall on the joint.

An alternative method

As I’ve suggested, it can be very difficult to keep the pieces of brass exactly where they should be because the masking tape loosens a little as the metal gets hot. If the solder melts and fills the joint quickly this is no problem, but for the various reasons listed this often takes longer. The photo below illustrates a method which I’m far happier with, and which produces far better looking results .. but it’s only worth spending the extra time if the set-up is to be used more than once.

a soldering jig created for a ladder form in brass

For this soldering jig I’ve used some tough ‘greyboard’, a recycled cardboard, of the same thickness as the 1mm rod chosen for the ladder form. I’ve cut and glued a complete template of it onto another cardboard base so that the individual brass pieces lie snuggly in these slots.  I’ve used this jig about 4 times so far and I don’t see why it shouldn’t last for more.


Selected suppliers and prices

Brass rod always in straight lengths, never as roll. Cheaper in 1m lengths rather than 300mm. e.g. 4D prices for 1m lengths (April 2015) 0.8mm £0.79, 1mm £0.98, 2mm £1.25

An alternative source is EMA Model Supplies .. for 91cm lengths 0.8mm £0.67, 1.6mm £1.27 .. but choice of thicknesses is very limited.

Solder Silverline 60:40 Tin/Lead Solder (4D £1.80 per 20g, available £4.00 per 100g) works very well! Melting point 183-190C.


The ‘grease’ type flux I always provide when teaching has always worked well, but I’ve had it for so long that the original container started to disintegrate .. so I don’t know the brand anymore! But one I’ve heard as good is La-Co Regular Soldering Flux Paste available from Screwfix £5.39 per 125g .. for use with copper, brass, lead and zinc.

Another one recognised as reliable is Fluxite Soldering Paste, suitable for copper and brass .. actually most metals other than aluminium (although other metals would require different solders) and can be used with either lead or lead-free solders.

On Amazon c.£10 for 100g tin and about the same from Jewson’s. Maplin just stocks the 450g tins for some reason, enough to last a few lifetimes!

Soldering Iron

SolderCraft 40W-230V (supplied with 5mm diameter chisel bit, stand and manual. 4D £20.99) Separate bits available £3.80. Around £18 on Amazon (with chisel bit) ..

From AllElectricRC this will cost £13.59 but supplied with a pencil bit .. still worth it ordering an additional chisel bit (AllElectric doesn’t have them)

Draper 71417 40W-230V on Amazon £15.95 (picture shows chisel bit, so I hope it is)

Draper K40P 40W-240V soldering iron

B&Q stocks a 40W soldering iron for £12.85 which looks almost identical to the old Draper model I have, above, and has a ‘chisel’ bit according to the product photos. This should be fine if it has been assembled with enough care.

Bench Stand Silverline brand, 4D £3.65 well worth getting (Antex shown in photo around £6) £5 from Maplin ..


See also

David Neat Model-making: Materials and Methods Chapter 4: Working with Metals

C+L Finescale. – go to the ‘Knowledge Centre’ for concise notes on materials and methods, including a chart advising on what solder and flux to use for different metals

4D Modelshop – a basic guide to soft soldering

The Basic Soldering Guide – this is written for its specific use in electronics but much of the advice applies.