Does Silicone Rubber Shrink After Curing?

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Silicone rubber is a popular material for mould making thanks to its flexibility and fine detail reproduction. A common question is whether it shrinks during curing and if so, how much it might affect the final result.

How Much Does Silicone Rubber Shrink?

Most liquid silicone rubbers are formulated for very low shrinkage. Typically, any dimensional change is minimal—making them ideal for projects where accuracy is important. Slight shrinkage may be more noticeable in larger or especially thick moulds. Translucent silicone formulations are sometimes a bit more prone to minor size changes, but for most small- to medium-sized applications, the difference is barely perceptible.

Minimising Shrinkage for Precise Results

If you require highly precise castings or moulds, there are a few steps you can take to control shrinkage:

Follow manufacturer instructions for mixing and curing times precisely.
Cure the mould at a stable room temperature away from excessive heat or cold.
Use silicone products formulated for low shrinkage, such as the “Pure Mould” Translucent Liquid Silicone Rubber, which provides reliable dimensional stability for crafts, resin casting, and wax injection.

When This Matters Most

Shrinkage becomes a concern if you are making moulds for parts that need to fit together or where measurements must be exact, such as jewellery, model making, or engineering prototypes. For decorative or non-precision items, minor shrinkage is rarely noticeable.

Related guides

How To Create Liquid Silicone Rubber

Understanding shrinkage helps you select the right silicone for your project and achieve the best possible fit and finish. For more tips on creating liquid silicone rubber and moulds, explore our main guide on how to create liquid silicone rubber.