How thick should silicone mould walls be?

For most sculpture moulds, 10-15 mm walls are standard. Smaller pieces (under 10 cm) can use 8-10 mm walls. Larger pieces (over 30 cm) benefit from 15-20 mm walls for rigidity. Too thin and the mould distorts; too thick wastes expensive silicone.

What is the difference between addition and condensation cure silicone?

Addition cure (platinum) silicone is more precise, has negligible shrinkage and is food-safe. Condensation cure (tin) silicone is cheaper but shrinks slightly over time and releases acetic acid. For fine art casting, addition cure is preferred.

How much silicone do I need for a two-part mould?

A two-part mould uses more silicone than a block mould because silicone surrounds the master on all sides including the top. Expect roughly 30-50% more silicone compared to a one-part block mould of the same master.

Can I reuse silicone from old moulds?

No. Once cured, silicone rubber cannot be melted or re-processed. However, silicone moulds last for dozens or even hundreds of casts depending on the casting material used. Resin and plaster are gentlest on moulds.

ArtCalcs

Mould Making Calculator — Silicone Volume for Moulds

Calculate silicone rubber volume for making moulds from master dimensions and wall thickness.

Master Length

Longest dimension of your master piece

Master Width

Width of your master piece

Master Height

Height of your master piece

Wall Thickness

Silicone wall thickness around the master

Mould TypeOne-part for simple shapes, two-part for complex

Silicone TypeAddition cure is more precise but costs more

How We Calculate This

How Mould Volume Calculation Works

Silicone volume = Outer mould volume - Master volume

The calculator computes the outer box dimensions (master + wall thickness on each side + base thickness), then subtracts the master volume. A wastage allowance covers mixing losses and air bubbles. Part A and B weights are split by the silicone mix ratio.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify quantities before purchasing materials.