Do Silicone Rubber Moulds Shrink Over Time?

How Much Do Silicone Moulds Shrink?

High-quality silicone rubbers, particularly platinum-based formulations, are designed to have minimal shrinkage. For most applications, any size changes are barely noticeable, especially with smaller pieces. Larger castings might show slight shrinkage over time, but this is generally not problematic for most crafts or commercial work. Choosing a silicone such as “Pure Mould” – Translucent Liquid Silicone Rubber for Mould Making can help ensure long-lasting dimensional stability.

Tips for Extending Mould Life

• Always follow the recommended mixing ratios for your chosen silicone product and mix components thoroughly.
• Use the moulds within their suitable temperature ranges and avoid sharp temperature switches if possible.
• Clean moulds gently and avoid abrasive cleaners or tools, as rough handling can degrade the silicone over time.

Proper handling will help your silicone moulds retain both detail and shape through many casting cycles.

When Does Shrinkage Matter?

If you are casting objects that must fit together precisely or require tight tolerances—such as jewellery components or technical prototypes—minimal shrinkage becomes especially important. In these cases, a high-quality, platinum-cured silicone is advisable to achieve reliable repetitions without dimensional loss.