Practice question · Multiple choice
Why does a flexible silicone mould usually need a rigid mother mould over it?
Hints
- Ask what holds a floppy negative in the right shape while resin is poured into it.
- The flexibility that solves the undercut problem also means it will not hold its own form.
Show the answer
C. Silicone has no shape of its own and would distort under the weight of the casting material
Why
Because the flexibility that solves the undercut problem also means the mould will not hold its own shape. Pour plaster or resin into an unsupported silicone skin and it deforms under the weight, so the cast comes out distorted. The mother mould is a rigid shell that holds it in position.
Practise Moulds I: Typology
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More questions on Moulds I: Typology
- Sort each mould by how it deals with undercuts.
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- Arrange the steps of deciding how to mould a form, in order.
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