Some of the principles of technical drawing simply illustrated – Part 1

Have a look at this drawing. This is ‘technically speaking’ a technical drawing .. but a naked one! It describes an exact three-dimensional form in just three views, just using lines to represent the visible edges.

Orthographic projection without scale

Technical drawing relies on a number of agreed assumptions: .. that all views are of the same object and only that object, but from different viewpoints and that all views are the same scale; that all visible edges are shown by a line and that we assume those edges progress away from us to form faces which are normally flat and at right-angles unless otherwise indicated elsewhere on the drawing; that there is no perspective used in the drawing. In other words our lines of ‘sight’ do not converge with distance but are parallel and perpendicular (at right-angles to) the face of the object shown; that wherever possible these views are ‘lined up’ with each other so that we can easily relate one to another, moving three-dimensionally in space, as it were, around the object and that most often the ground-plan view is placed at the bottom because it is the ‘basis’ from which all else is elevated.

If you had not read  the above and had never seen a technical drawing before you wouldn’t be able to read much with certainty from these shapes. But when one takes on these agreed assumptions .. known as conventions in technical drawing .. one can start to read it, deducing various things, albeit not with complete certainty yet.

For example, if the bottom view is the ground-plan view then the shape above it is most likely to be the front face because it’s the same length and it explains that the line we see dividing the bottom form is because the block extends upwards at that point. Because the shape to the right of the front view is lined up on the same ‘level’ we can assume we’ve turned on a horizontal axis so it’s a side view and it looks the right width if we compare this to what we see on the ground-plan. We can be certain that we are looking at the left-hand side because this is the only view that fits with the other information we’ve got. We’ve had to do a small amount of mental/spatial visualization to get this! As I’ve said, this drawing has been stripped of all the additions which are supposed to make it easier to read than a visual puzzle .. but nevertheless a certain amount of mental visualization is always needed.

simple orthographic layout

Of course it all becomes easier to interpret if this is added .. a simple 3D line drawing using perspective! Now we can see clearly that we were right about the ground-plan view and the front, although we still have to use our power of visualization a little for the side. Despite being undeniably helpful, perspectival views haven’t been common in technical drawings up to now. This is probably because they take too long to do and are somewhat outside the skills or motivation range of most draughtsmen. It may also come from the purist notion that technical drawings shouldn’t need them, or that it even goes against the rulebook of using a language devoted to strict parallel projection. But nowadays it’s so easy to create perspective views in programmes such as SketchUp and either print or trace them, with or without shading, onto the drawing if there is an available space to put them.

The first version shown above satisfies many of the fundamental strictures of a proper technical drawing .. but of course not all. The most important missing are scale and measurement. Here below is the same drawing .. now almost fully ‘clothed’. Now it is clear what size we are dealing with .. the scale used for the drawing is given in the block of information commonly termed the title block and in any case the measurements are also displayed. We could get all the measurements if we scaled up the drawing 10 times (the scale given is 1:10) but the inclusion of most (often not completely all) of the measurements is a recognised courtesy, so that the reader of the drawing doesn’t have to use the scale ruler for everything. It’s also possible that a drawing can distort during copying, whereas written measurements remain exact. Also, if the scale is there but no measurements given against any lines, how can you be certain that the drawing has been copied at 100%?

basic orthographic drawing with measurement info

These measurements are written in millimetres here, the most common practice for theatre in the UK and increasingly now .. thank goodness! .. in film and television. Notice how the longer, overall measurements are kept a little separate to make them easier to find and notice how heights and lengths are not needlessly repeated. Notice how these ‘clothes’ sit .. comfortably, with some breathing space. The structure itself is still very clear, because the measurement lines are thinner and spaced a little away from the edge of it. Because of this the beginning and end of each measurement line needs to be emphasized, hence the slight crosses. Notice also that the measurements are written to be read in just two directions, from bottom-top and left-right .. rather than circling like ants!

We now also have important written information .. the views are labelled to remove any remaining doubt and the title block has, as the name suggests, a title! The sheet is identified as ‘1 of 3′ and the version dated. All this, and sometimes more, is necessary to keep track of what might become a large batch of drawings within a single project.

But what is represented here is a very simple form which assumes no significant surface detail. I intended this playground ‘street furniture’ unit to be made of brick and chose the dimensions to conform to standard brick measurements, but I wanted a specific pattern. When the designer intends an appearance which directly affects the construction of it, this information must also be on the drawing. I also had to draw all visible sides first in scale just to work out how standard bricks could be laid in the pattern I wanted. This illustrates yet another fundamental .. that measured drawing is not just a final rendition after all design decisions have been made, but an important tool for working things out even in the early stages.

complete orthographic information

The drawing is now starting to look more typical of the densely packed set drawings you may have seen if you’ve had a chance to look at any from theatre, film or television. The perspective view has had to go, to make room for the two remaining elevations as they’re now called, and to avoid any possible confusion arising from ‘back’ or ‘front’, ‘left’ and ‘right’, these are given letters which correspond with clear indications of viewpoint arranged around the ground-plan. This is a more sensible method, because these pointers not only indicate the direction of view but also where the point or rather the plane of view is. The identification and linking of parts of the drawing by means of letters and symbols is known as coding.

Notice also how the measurement lines are now arranged .. overall measurement on the outside with more detailed divisions closer to the object. The line bordering the sheet may seem just a presentation nicety .. but it actually has a more serious purpose. When the drawing is copied it indicates that the whole drawing has been copied, i.e. with nothing missing at the edges.

So, in conclusion to this first part, the ‘principles’ I referred to in the title are firstly those general and often unspoken assumptions I listed at the beginning, plus the following which I’ve tried to illustrate in this article, namely:

.. that technical drawings need four qualities above all else: accuracy (both drawn and written measurements should be correct, precise and in the right place); clarity (both meaning and appearance should be clear and readable); consistency (the ‘language’ used should be used in the same way throughout); economy (the drawing should be uncluttered by needless repetition)

.. that the layout, the arrangement of views on the sheet, is fundamental to the understanding or ‘reading’ of what they mean

.. that technical drawing primarily involves common sense in the way three-dimensional structures are represented in line but that common sense alone is not enough to either create or to read them. The special language of conventions has been developed to assist and it is expected to be used. This reduces the amount of mental visualization we need to employ when trying to understand three-dimensional space from a two-dimensional drawing, but it will always involve some!

.. that there should be no room for misinterpretation, no ‘reading between the lines’. The reader of the drawing should not have to make guesses outside of the agreed ‘assumptions’ or conventions referred to.

.. that the object views themselves should be treated a lot like VIPs or ‘untouchables’ .. clearly defined, with everything else at a respectful distance

.. that technical drawing is not just the ‘final account’ where all the sums are checked but an important tool in developing the design

.. that at the very least the primary measurements should always be written even if the scale is clear and that this is not only a courtesy but also allows the reader to check the accuracy of the copy

.. that the drawing should include all important information that directly concerns the structural making of the object or anything in ‘relief’ but doesn’t usually include details of painted design or colour. It is also generally agreed that the designer’s responsibility is to convey what is seen but not necessarily how it will be made

So far though I’ve illustrated using a simple, solid object which doesn’t bear much resemblance to a theatre or film set .. we’ve dealt with a simple block from ‘without’ rather than a box from within. When something like this is the object of the drawing there are some major differences .. the layout usually has to be different, the ground-plan contains much more information, and there is often the need for sections in addition to elevations, a device we haven’t considered yet. These and other things will be featured in Part 2.


5 favorited in July – Institute of Making, Grace Emily Manning, Salao Coboi, Edwina Camm, Casting About

It’s about time that I started a Links page .. because there are so many useful websites or examples of inspirational work I’d like to share .. so I’ve set it up above and hope to add to it whenever I can. Here are the first few entries .. just the first ones that came to mind.

Salao Coboi

Salao Coboi sculpted figures

Although the figures produced by ‘Salao Coboi’ reference the familiar from comics and toys, there’s also much about them that’s really quite unique. Salao Coboi means ‘cowboy salon’ and the name was adopted by a Portuguese artist’s collective in 2009, though the figures exhibited from 2011 onwards are largely the work of the group’s co-founder Apolinario Pereira. Although they may look as if they should be small, many were more than a foot high and produced as hand-painted resin casts in limited editions.


Institute of Making

Institute of Making

The Institute of Making describes itself as a ‘cross-disciplinary research club for those interested in the made world’, opened in March 2013 and housed in the Engineering faculty of University College London. Full membership of the ‘club’ is only open to UCL students and staff .. but the website, the excellent Materials Library and a variety of talks and workshops are open to the public. This is not all about the search for flexible concrete or transparent aluminium .. recent public masterclasses have included spoon-carving, felt-making, animatronics and ‘low-cost 3D scanning’.


Grace Emily Manning

Screenshot from the intro of 'Pupa' by Grace Emily Manning

I first saw Grace’s work at her BA Performance Design and Practice degree show presentation at Central Saint Martins this year. Her 7.49min stop-motion animation Pupa is what I’d call ‘the genuine article’ .. charming, unpretentious, and really well-made for what it sets out to be, in her words ‘motivated by non-precious childlike creation’ and founded on exploring tactile and material experiences. It’s certainly one of the most glutinous, squashy and fibrous pieces of animation I’ve seen!


Edwina Camm

Edwina Camm 'The Tale of Thomas Dudley'

A couple of years ago, when I was doing my usual sessions on ‘white card’ model-making for film/tv production design students at Wimbledon College of Art, I searched around for some more interesting examples combining model and drawing .. and found exactly what I had been looking for in Edwina’s work! Edwina originally studied film/tv design at Kingston but then went on to do an MA Illustration Authorial Practice at Falmouth. The image above is from her own on-going project ‘The Tale of Thomas Dudley’ for which she combines narrative, 2D illustration and 3D models.


Casting About

Richard Arm, Casting About homepage detail

This useful, well-organized and friendly looking ‘how to’ website .. a ‘dedicated electronic resource for mould-making & casting methods and materials’ .. is the work of Richard Arm, Senior Technician/Lecturer in the School of Art and Design at Nottingham Trent University. It is perfect for anyone looking for a clear introduction or an overview of the creative possibilities.

Does foamed PVC have a grain?

Although this question will not be of much value to most people, it is certainly of interest to those few .. like myself .. who work with this material. The answer is .. yes, it does .. and this has a significant bearing on how one can get the best out of it! I have to confess that even though I’ve been using it for years, I’ve never properly realised this until now. There’s hardly any visible indication and although I had noticed at times that cutting in one direction seemed slightly harder than another I didn’t attribute a cause. I’d always assumed that sheet plastics just don’t have a ‘grain’, or rather a directional difference, because of the way they’re made and this would be especially so with foamed materials. In all these years I’ve never noticed any reference to a ‘grain’ in any of the product information available .. until now.

I should point out that I’m going on the basis of the tests I’ve made with the brand I use, which is Palight and Palfoam foamed Pvc manufactured by Palram. But I’m assuming that the manufacturing process for foamed Pvc will differ very little between the various brands even though there is often a difference in hardness. After looking more closely at the manufacturer’s documents available for download, I found this tucked away in some notes entitled ‘Installation':

‘Palight is manufactured as an extruded foam PVC product with a directional grain running the entire length of the sheet. This manufacturing process gives Palight greater flexural strength in the direction of the extrusion. The grain of the Palight should always be installed perpendicular to the fastening point.’

In other words if a thin strip is cut along the direction of the grain this will have more rigidity than the same strip cut at a right-angle to it or ‘against’ the grain .. just like wood! To test this, amongst other things, I first had to find a way of recognising the grain direction, because as I’ve said .. it’s hardly noticeable when looking at the surface or the cut edges! If you hold a piece of Palight up to the light (better still a light that’s glancing the surface) and look at it closely, then rotate the piece 90° and look again, you may just about discern a faint direction of surface texture in one of these views. Another test involves making an indented line with a metal point, such as an embossing tool, a nail or a compass. Along the grain progress will be fairly smooth and hardly make any sound, whereas against the grain there will be a higher, scratchy sound and the surface will resist a bit more. A third test just involves cutting a strip, and is perhaps more noticeable in the thicker versions of Palight. I tested with squares of 1mm, 2mm and 5mm Palight, cutting strips just 5mm wide, first along one edge of the square and then the other. I made sure to keep my exertion with the knife roughly the same, and I found that I consistently needed a couple more strokes to cut against the grain. These strips were also noticeably more bendable than those cut along the grain.

So, I’ve already implied the possible advantages of utilising the grain direction and I’m guessing that the following will apply to all thicknesses .. having tested 1mm, 2mm and 5mm with the same results.  Thin structures will be stronger if the grain follows their length, and they will also be easier to cut! If strips are intended to be bent, this will be easier if they’re cut at a right-angle to or ‘against’ the grain. Finally, and as I’ve illustrated in my page ‘Palight’ brand foamed Pvc under constructing in the Materials section, Palight can be scraped with sandpaper to simulate a wood-grain surface and this will be easier following the actual grain of the plastic. Pvc can also be embossed, ideally using a smooth-pointed embossing tool, and a slightly different quality of line is produced either with or against the grain. You’ll have to try it out, to see which you prefer.

How to refurbish a cutting mat

A cutting mat should only be used to cut on and not as a general work-surface for all sorts of other things such as gluing and painting. I try to say this to everyone I’m teaching .. and I try to remind myself of it whenever I’m working. Even the slightest spots of paint can contribute to diminishing the purpose of the cutting mat, because it’s not just table surfaces that cutting mats are supposed to protect .. it’s also us! The surface of the cutting mat is designed to grip, so that when for example one’s pressing down firmly on something while cutting it, it’s less likely to slip around. If that happens it not only makes it difficult to cut cleanly .. it also makes it dangerous!

But the practical fact is that it’s often a real bother to take the cutting mat away every time one’s finished cutting something. Few of us have the luxury of large workspaces where separate ‘stations’ can be reserved for separate tasks. Usually everything gets done in the same tight table space, the one where the light is best .. and the cutting mat gradually becomes a playing-field for just about everything involved. If we accept that the cutting mat needs to stay put, a better way of cleaning needs to be found.

I’ve tried various ways of cleaning cutting mats in the past .. scrubbing with detergent, scraping with paint scrapers or razor blades .. but none have been that effective. There is certainly no way of removing superglue from the rubber with a knife-blade without damaging the surface. But recently I tried a different approach, and it worked surprisingly well!

cutting mat with superglue

Above is a portion of a cutting mat with a dribbling of superglue .. very common! Unless it is wiped immediately from the surface superglue will set to a rock-hard mass. But superglue is brittle .. one reason why it never lasts if it has to fill even the slightest gap .. and although near impossible to carve into, the surface can be easily broken down by abrasion. It only takes a couple of minutes .. below is the same portion of cutting mat sanded, using first a coarse (60 grit) sandpaper to break down the raised parts and then a finer (120 grit) one to finish the surface.

cutting mat sanded

This will only work properly if the sandpaper is mounted on blocks, such as the ones I make shown below, which will give the abrasive surface maximum strength and also ensure that sanding remains flat and even. If careful, even most of the printed grid can be preserved and the slightly roughened surface actually enhances the cutting mat’s grip.

sanding blocks 60 and 120 grit

Another thing that can very easily happen to a cutting mat is that it can warp .. but only with heat! I can remember, when we used to get a consistent run of hot days, if a cutting mat had been left on a studio window-sill it would end up permanently warped .. no amount of bending or leaving flattened down under heavy books would alter this. Unfortunately this is the end of the story! I’ve tried laying cutting mats in hot water, or laying newspaper on top and ironing them .. they can’t be flattened again. I’m assuming this is because cutting mats are composed of bonded layers, with a tougher interior layer. Heat causes the top layer to expand but the interior layer is less affected, and the top layer does not contract properly again on cooling. On the other hand cutting mats can take a lot of physical bending without any permanent harm i.e. if bending them makes transportation easier I’ve always found that they’ll lie completely flat after about half an hour.

But here’s an alternative idea for making the working situation easier! When I first started out I remember that I invested in the largest cutting mat I could find .. A1 size .. thinking that I would then be prepared for any eventuality. On the diagonal the maximum cutting length is a little over a metre. But I rarely had the free space to use this without a time-consuming clearup! Over the years I’ve acquired at least one of every size of cutting mat, starting with A5, and by default now I use the smallest one I can get away with for the job I’m doing. If I’m suddenly faced with having to cut a much longer line I’ve found it more practical just to place two A3 cutting mats on end, giving a maximum reach of up to 940mm on the diagonal with a little margin. I also keep one very small, A5, cutting mat purely for fine or intricate cutting. Even after a lot of use the surface looks hardly touched, because it’s not subjected to much pressure, so I can rely on it to remain the best support for delicate work.

Modelling with Milliput

Here is the page on Milliput I’ve just completed for the Modelling part of the Materials section. It’s a summary of all you’ll need to know about this modelling material, together with a few suggestions re. similar products. I only discovered recently that Milliput can be pushed .. if heated carefully with a heat gun .. to cure rock-hard within minutes.

My page entries are usually meant to be added to and often start with general outline information, price guidance, suppliers and useful links followed by my worklog where I can put further info and photos when I have them.


Milliput is a 2-part, very hard-setting epoxy modelling putty, available in two fineness grades and a few different colours. It is most suitable for small, delicate work. ‘Standard’ Milliput is a light yellow/grey colour when mixed while the extra-fine grade is white. When equal amounts of both parts are thoroughly blended together (until the colour is uniform) the putty begins to harden, not requiring additional heat to cure. It remains easy to model for around 40-60mins, after which it gets gradually more ‘rubbery’ (but see below for making use of these changes while modelling).

Milliput standard grade

Advantages of using it

It sets much harder and stronger than most other modelling materials .. stronger than fully baked Sculpey for example .. and this final hardness is not dependent on bulk i.e. very small forms will cure just as hard as larger ones. This makes Milliput (more especially the fine white version) more ideal for delicate forms.

1:25 figures modelled in Milliput. First stage of modelling

The 1:25 figures above were modelled with a blend of ‘Terracotta’ and fine white Milliput. They represent the first modelling stage after completion of the wire armatures described in the post Modelling small-scale figures – Part 1: ‘twisted wire’ armature from March 2013.

Milliput sticks very well to a variety of materials, again unlike Sculpey, and is often used for repairs or as a gap-filling cement. It is commonly used in the restoration of antiques and art objects because of it’s high adherence and its strength when cured.

Once it has hardened it can be easily sanded and tooled (i.e. sawn, drilled), even carved with a scalpel. Scraping with the scalpel can work particularly well for fine smoothing once fully cured.

There is no noticeable shrinkage, and that coupled with its strength means that it’s very unlikely to crack.

Unlike most 2-part epoxy materials it can be used with water! This can be used to help smooth the surface while modelling, or water can even be mixed in to make a softer paste i.e. to use as a gap-filling cement or to join Milliput parts while working. But Vaseline on the fingers can also be effective for fine smoothing, as is methylated spirits.

When used as directed and left to cure on its own it will harden more quickly than air-drying modelling materials, reaching an apparent full hardness in 3-4 hours (though full curing will continue for a few more). However, this can also be accelerated by using heat and, with care, Milliput can be rendered rock-hard in a matter of minutes (see .. below). Even if the advantage of heating is not taken up, benefit should be made of the fact that it will start to become firmer after about 40mins .. so for example basic modelling could be done first and then later, when this becomes a firmer support and the surface less sticky, detail modelling can be easier.

What it can’t do

It is very sticky when first mixed, noted above as an advantage, but this also means that it can clog the fingers annoyingly while modelling .. when I’m working with it I need to have a moistened flannel on hand to keep them clean.

Even in its freshly mixed state, Milliput has more ‘push-back’ than modelling wax or Super Sculpey .. i.e. it is slightly rubbery. This increases as it cures and starts to get firmer, so for example after a full hour impressions can still be made with modelling tools but they will diminish a little as the material springs back.

Because of the cost relative to other modelling materials Milliput is not a viable option for large work (see cost comparison of different modelling materials in Modelling and shaping, part of the Making realistic models series in the Methods section).

What it costs and where to get it

Milliput is sold in most good art or hobby shops such as Tiranti, 4D  Price (2014) c.£2.28-£5.06 (Tiranti) per 113g packet dependant on type (ranging from standard to fine grade and colours e.g. terracotta, black). See ‘Quick view materials info’ for ‘modelling’ in the ‘Materials’ section for current suppliers and prices.

Working life

According to the manufacturer it has a shelf life of c. 2yrs if stored cool, dry, sealed in polythene bags provided.. but see notes below.

Further info sources


July 2013

At the time of writing I have not found any other epoxy putty to compare with it. You may come across similar looking 2-part epoxy putties in DIY shops but these are not marketed as ‘modelling’ material and tend to be even more expensive. An exception may be Magic Sculp which looks promising but I’ve yet to try it .. see below July 2014.

Apparently the setting of Milliput can be speeded to just a few minutes by applying heat (Tiranti website) .. but see June 2014 below. Best method of mixing; portion equal amounts and press these together, then roll this into a long ‘string’, gather up and twist together then roll long string again .. repeat etc. After 3-4 hrs hardening, it needs at least the same amount of time to fully cure. Heat resistant up to 130C. Can be coloured by blending in powder pigment (or even oil paint, or spirit-based colourants) while mixing. Different Milliput versions are intermixable but also resin or hardener parts between them (as long as one knows which is which) are interchangeable. The ‘hardener’ is usually the darker of the two and will develop a resinous crust over time. If used as a press-casting material, ‘talc or a light oil’ can be used as a releasing agent according to the Milliput website. Another tip from this website is that, if you have to interrupt work during modelling, it will keep in its uncured state for up to 36hrs if put in the freezer.

How to model with Milliput Use should be made of the fact that Milliput will change in consistency as it cures i.e. for the first 30mins rough build-up when at it’s softest, after which fine detail especially imprinting and smoothing are easier once its getting firm. Carving can be done after c. 2-3 hrs when almost set, then sanding/filing after 3-4hrs.

Accelerating hardening 7/2013 ‘Tips’ found (not yet verified) include: baking in oven (max 50C) for 30mins. Since cured Milliput is heat-resistant up to 130C successive adding/baking is possible (but see later addition June 2014 below).

How long will Milliput remain usable? I recently made a test of some Milliput I’ve had for at least 10 years. In fact, I was going to throw it away because it had become rock-hard and the darker ‘hardener’ part (as I assume it to be) had developed a tough, resinous skin. I was surprised though that after managing to chop off two equal pieces and starting to squeeze them between the fingers they became softer and eventually soft enough to start mixing together. For this first test I left the tough skin on, believing that it might still blend, but it remained as small hard granules.

mixing Milliput

Above, my usual method of mixing Milliput is first to combine the two parts roughly and then start rolling the mass into a long thin string, which I then divide, twist the strands together and then repeat a few times until the colour is even. The hard fragments of skin remained so I tried chopping and pressing the mixture on a tile in case that got rid of them.

mixing Milliput_2

It didn’t help much, so I stopped blending (it had taking altogether about 20 minutes) and left the piece to harden, below. The consistency was not good (compared to fresh Milliput), ok perhaps for rough work but rather fibrous and prone to fissuring when stretched.

10 year old Milliput

I did another test but this time peeling off the crust from the darker Milliput stick, just using what remained. This mixed very smoothly, a little harder than new Milliput but still a good, smooth consistency, below. I needed 10 minutes to mix it thoroughly.

crust removed before mixing

I’ve never properly timed the setting of Milliput up to now and I’m glad I did that with these tests because I’ve generally been telling people that they have about an hour to model with it. In fact it’s much longer .. if one can make use of the changes to model differently (and later carve) as it toughens. I made a further control test using new Milliput in addition to the two above.

10 year old Milliput with ‘skin’ included After 1 hour firmer but still could be kneeded and modelled; less sticky, and ideal in this state for impressing with tools; little rubbery ‘springback’ as yet i.e. marks made with tools stay as made. After 2 hours no longer easily kneeded or modelled, but still very flexible; still easily cutable with a knife; still good for impressing though slight ‘springback’ i.e. marks made with tools fill in a little; easier to smooth the surface without distorting the form.

10 year old Milliput with ‘skin’ discarded After 1 hour same as above. After 2 hours same as above, though a little firmer and impressions spring back more

Both tests After 3 hours still cutable with a knife; still bendable, but no longer mouldable; can be squeezed but springs back like rubber and impressions do not hold; very good for carving. After 4.5 hours like tire rubber; ideal state for carving

New Milliput thorough blending took 10 minutes. After 1 hour still very soft, a little firmer, a little less sticky. After 2 hours still mouldable and very flexible; cutable with a knife; still takes impressions well with minimal springback, but fissures occur when trying to ‘smear’. After 3 hours no longer mouldable; still flexible and cutable but impressions do not hold.

7/2013 the nationwide £shop chain ’99p Stores’ now stock a form of mixable epoxy putty from the ‘Do It Right’ brand. This is packaged in small, pre-portioned pellets which one just has to blend together. Each pellet is c. 4g and there are 8 to a pack so this doesn’t work out any cheaper than standard Milliput.. just could be easier to get hold of on the ‘high street’. It has different properties though, as one can guess from the smell which is more like regular epoxy glue than Milliput. For a start it’s much softer and stickier when first mixed (so much so that using one’s fingers becomes rather difficult) and there’s a graininess that doesn’t really disappear. The only other possible advantage (depending on what you use it for) is that it sets up much quicker than Milliput; in my test it was a bit too firm to model with after 15 minutes and had reached almost complete hardness after 2 hours. When fully cured it was also very strong. It may be ideal as a gap-filling glue or repair medium, but not so good for modelling.

'Do It Right' putty

The mixed test piece above was gently flattened and pulled out in the same way as the Milliput tests but the graininess and fissuring are apparent here.

Heating Milliput

June 22 2014

The Milliput website (address in the main text above) mentions that the curing of Milliput can be accelerated with heat but goes no further in explaining how much heat or how much quicker this can be. I recently did my own test .. mixing up a little standard (yellow-grey) Milliput and quickly modelling a basic head, torso and arms on a very small (1:25) figure armature of twisted garden wire (see Modelling and shaping in the Making realistic models series in the Methods section). I used brand new Milliput, which was particularly soft. For a heat source I used a Wagner brand ‘Heat Tool 400′ which is a hand-sized heat gun, not so available in the UK anymore but a similar type can be found in Hobbycraft. This type has only one heat setting and will deliver a temperature of up to 400 degrees C, but this represents the local temperature reached if it is focused on a spot for a length of time, and it is normal to keep the heat gun and/or the victim moving, when baking Super Sculpey for example, because otherwise it will quickly burn!

I held the heat gun at a careful distance of c.20cm from the figure parts and moved it back and forth while also rotating the figure slowly. I estimated that it had been about 15-20mins since the Milliput had been mixed. I noticed after about 10secs that the Milliput surface was starting to ‘bubble’ very slightly and appeared to expand a little, but when I took the heat gun away the bubbles disappeared. From that point I was very careful, heating very slowly and I noticed that gradually I could move the heat gun closer without the surface blistering. I gave it around 5mins heat gun treatment all over, then left it to cool down. On cooling the figure was rock-hard, just as if left to cure normally and carving with the scalpel showed no weaknesses in the surface.

The hardened Milliput showed no signs of the earlier blistering. Gentle, more gradual heating may have solved this; or starting with a lower temperature then building up. It may also be prevented if the material is allowed to cure a little more first i.e. 30mins after mixing rather than 20, or older Milliput may even react better .. I’m guessing now, it’s something I intend to test so if you want to try this method it would be worth doing the same first.

July 2 2014

From what I’ve recently read Magic Sculp may be well worth trying! It sounds identical to Milliput in all respects .. working/hardening time, water-solubility, toughness when cured, effect of heat etc. .. but with better price options. For example, when ordering from the UK website, a 200g packet will cost £8.40 inc. VAT and standard 3-4 day delivery is also free. This is more expensive than the best shop price (Tiranti) for the standard grade but cheaper than the other white or coloured types. Magic Sculp is available in natural/grey, white, flesh colour or black .. all the same grade. The natural/grey is perhaps a comfort for those who may be slightly sickened by the ‘yellow/grey’ weirdness of standard Milliput. But the advantages over Milliput may increase if one needs larger amounts. For example 1.6kg will cost £34.99 including VAT and delivery, giving a price of £2.47 per weight of a Milliput pack, for a product which is, according to others .. finer, softer and in colours!

Magic Sculp like Milliput, is a UK product. I rang the manufacturer and I was told that the reason why there’s a ‘Magic Sculp’ here and a ‘Magic Sculpt’ in the US .. with a ‘t’ added, if you didn’t spot it! .. is that the US firm copied the UK product and the agreement was reached that ‘Magic Sculpt’ would only be sold in the US. I was also told that Magic Sculp is softer to work with than Milliput because it contains less clay filler. As I’ve said, I haven’t worked with it yet, though I certainly intend to .. so you’ll have to judge for yourself how it compares. If there’s anything you think I should know, I’d be happy to hear it!

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