LENHAM POTTERY MODELS
making high-fired semi-porcelain models since 1969
Seven steps to the Shire Horse Model: Step Four

This is
Step Four:
Making the rubber model

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Back to
Step One:
armature


Step Two:
modelling

 

Step Three:
intermediate
mould-making

 

Step Five:
plaster
production
mouldmaking

 

Step Six:
slip casting

 

Step Seven:
fettling and finishing

 

Back to the
Introduction

 

Making the silicone rubber permanent model, Page Two of Two.

 

Plaster jacket and rubber mould ready to fill with resin.

 The plaster jacket is around the rubber mould, which has been partly filled with brown silicone rubber. Now the mould is ready to be filled with casting resin, the first mix is not over-catalysed and so is runny and remains liquid for longer. The subsequent mixes have more catalyst, and are stiffened and strengthened with vermiculite. Casting resin heats up as it cures. This causes it to expand. One result is good - it forces the liquid first mix into all the cracks. The second result is bad - it can force the mould apart, which is why it is strapped up with strong luggage straps pulled as tight as possible.
The rubber model and the original plastilene model compared. The rubber model in the foreground is the same size and shape as the original plastilene model at the back. The filling hole on the rubber model is left as it will be needed when making the production mould. The flat area onto which the tail is attached needs to be as large as possible and yet the filling hole also needs to be as large as possible.

The next step is to make the production mould.