For the five days we’ll be working together we will be focusing on how to make moulds of objects and how to cast in them .. of course, that was Jasmin’s main reason for inviting me here. But in the process we’ll be trying out more than that! Firstly Jasmin suggested that we practise how to make a scale model figure, and we will be making one that can be converted into a more suitable object for casting. Secondly, I wanted to show you what can be done with Kapa-line foam (the foam part of Kapa-line foamboard), so we will also be making small ‘architectural’ forms using that material. Lastly, the method we’ll be using for making parts of a model chair (so that a flat mould can then be made and the chair parts cast) is also the method I would recommend for individual pieces of furniture in other materials such as wood.
The three moulds you’ll be making will be in silicone rubber, the best and really the only material for doing this kind of work properly. All three of the moulds will be of the same type, simple ‘one-piece block moulds’ (created by fixing the original form on a flat surface and pouring silicone rubber as a block over it). But in mouldmaking and casting ‘simple’ never means ‘limited’ .. in fact it’s the opposite! Aiming for something ambitious and only being able to achieve it in a complicated way .. that limits the possibilities! On the other hand being equally ambitious but determined to achieve it in the simplest of ways .. that liberates other possibilities!
If we’d all tried to make a more complex multi-piece mould to cast a fully 3D form in the time that we’ve got, we wouldn’t get to do much else! On the other hand, it’s certainly valuable to get a clear idea of how it can be done. For that reason I’ll be making a two-piece fully 3D mould during the five days and explaining the process, so that you can see it being done step-by-step.
I said that we will be making a model figure (in the proper way, starting with a wire armature, and then building up simple ‘body masses’ on that) but that we will then ‘convert’ it. What I meant was that the figure will then become a ‘caryatid’, a piece of figure sculpture which merges with the architecture. It will still be fully 3D, and seen from all sides, except the back. I will be providing sheets with two types of image reference to help with the modelling .. sculptural references (images of stone figures, some of which you may be familiar with) and anatomical references (clarifying what shapes go together to make a human body .. odd that we don’t really know well enough when we have to model one!). But additionally there are all the reference images that I’ve collected together here .. the idea being that you can get a sense of what we’ll be doing before we start, and you can then access them while working in the studio.
Just one last thing! In my view ‘rough and expressive’ is much better for this, and more powerful than ‘smooth and refined’ .. and more practical in the time that we’ve got! With this in mind I’ve put together a number of images here in the folder ‘Expressive modelling’. Don’t get too ‘precious’ while modelling .. the word, I think, is close to ‘penibel’ in German, possibly ‘pedant’ in Austrian .. but the sense is ‘striving for unnecessary and self-defeating perfection’.
Please note that I’m just guessing we’ll start at 10.00 each day .. it can be earlier if that’s what you’re used to! With a 10.00 start we should finish by 17.30 at the latest, if all is going well, but it may be necessary to stay a little longer if we are getting behind. We should be able to discuss this in advance during the course.
10.00 Introductions Fundamental principles of mouldmaking and casting. How can it be best applied to model-making? The importance of getting the most out of simple methods. What we are aiming to achieve in the week? Quick advice for taking process photos throughout the work.
11.00 Making a 1:20 scale chair model for moulding/casting Constructing the chair in flat parts using basswood (lime) strips glued to a paper drawing-template. Tools to help with fine, small-scale construction.
Looking at other examples of simple, flat moulds made to produce complex objects. Showing examples using the same ‘template’ method to make one-off pieces of wooden furniture.
14.00 Making a silicone rubber mould from the scale chair Preparing the prototype, building the mould box. When is a ‘barrier agent’ necessary between the original and the silicone? General types and properties of silicone rubber i.e. ‘platinum’ cure, ‘tin’ cure, special silicones for different purposes. How is the choice made of the best type for the job? Calculating quantities. Ensuring a tight seal. Mixing and pouring the silicone, leaving to cure.
16.00 Making a simple block design using Kapa-line foam Tools to assist with shaping foam. Properties and uses of Kapa-line foam. Preparing the block form for mouldmaking.
First stage of 3D mouldmaking demonstration which will show clearly step-by-step over the 5 days how a more complex mould for a fully 3D object is made. First stage, embedding the object up to half-way in a soft modelling material.
10.00 ‘Figure within Architecture’: modelling a 1:20 scale ‘caryatid’ type figure against an architectural setting
Explaining the aims and outcomes of the exercise, looking at reference images. Shaping the architectural piece. Further special tools for foam shaping. How to texture and apply relief detail to the Kapa-line foam.
12.00 Unpacking and cleaning up the previous day’s chair mould Making sure the mould can lie flat, etc.
14.00 Making a 1:20 scale figure armature ready for modelling The importance of the armature; not just as support, but as a proportional guide. Modelling as flat first, then bending into a pose.
15.00 Modelling a figure in stages using Super Sculpey Properties and benefits of Super Sculpey compared to other polymer clays. Looking at figure reference resources and tips for small figure modelling.
Second stage of 3D mouldmaking demonstration Making a containment wall, and pressing ‘natch’ or locator marks in the clay. Applying the silicone ‘detail coat’ on the first half. Adding a special ‘thixotropic’ agent to silicone to turn it into a paste. Spreading a 1cm thick layer on top of the detail coat to create the first silicone half.
10.00 Continuing with figure modelling
Putting together with the architectural base. How to attach Sculpey to foam. Controlling ‘undercuts’ and filling in ‘windows’.
15.30 Preparing shaped/modelled assemblage for mouldmaking Sealing the foam surface, building the mould box. Estimating amount of silicone needed to fill, mixing up and pouring, leaving to cure.
Third stage of Second stage of 3D mouldmaking demonstration Making a plaster supporting ‘jacket’ on the first silicone half, leaving to cure.
10.00 Casting 1:20 scale chairs in polyurethane resin Setting up for casting work. How to work with polyurethane resins, their main properties and benefits. How to work with small moulds and casting in small amounts. How to colour polyurethane resin. Looking at some common, and not so common, ‘fillers’ added to the resin for larger work. Making a few castings, trimming the casts while they’re still in the ‘green stage’.
A brief summary of other resins and the differences between them.
11.30 Trying out plaster and cement castings in the ‘block form’ moulds What are the differences between plaster and cement? The common types of plaster, what they’re good for, what they’re not, and how to work with them. Making test castings in plaster and cement. Using pigments to colour.
14.00 Casting in the larger ‘base/figure’ form Starting with a polyurethane resin cast, this time in stages. Then possibly trying a ‘hollow’ cast, adding plaster to the resin to make it thicker and more spreadable (but only if the particular plaster and resin we’re using there will work together in this way).
Finally a ‘stone’ plaster casting, starting with a ‘detail coat’ first.
Other ways of dealing with air bubbles in plaster.
Fourth stage of 3D mouldmaking demonstration Turning over and cleaning up the first mould half. Cutting air-release channels in the first mould half if necessary. Greasing with Vaseline as a barrier agent. Repeating the detail coat, then the thick silicone skin on this second half, leaving to cure.
10.00 Working with clear epoxy resin Properties and uses of epoxy resins. Making a clear epoxy cast in the smaller ‘block form’ mould, leaving to cure
11.00 Final stage of 3D mouldmaking demonstration Making a plaster supporting ‘jacket’ on the second silicone half, leaving to cure. Once plaster has set hard .. taking the mould apart, removing the original, then making a test cast in polyurethane resin.
The remainder of Day 5 has been left unscheduled for now, partly to allow for more time if anything is taking longer than anticipated .. but also to give some time for individual choices if anyone has them, or to answer individual questions.