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FacebookMould Shrinkage and Durability Over Time
← Back to Review of two-component silicone rubber for mould making
Quick answer
Silicone rubber moulds used in casting and craft applications typically demonstrate minimal shrinkage and strong durability, especially when manufactured from quality two-component silicones such as “Pure Mould”. These moulds are resistant to wear and can be reused for numerous casting cycles, provided they are mixed and cured according to manufacturer recommendations. Slight shrinkage may occur, but this is most noticeable in larger items or when improper mixing ratios are used. Overall, silicone rubber is valued for its ability to maintain shape and reproduce fine details over time.
For makers and professionals who depend on mould precision, the performance of silicone rubber over repeated uses is a practical concern. It’s helpful to understand how shrinkage and degradation can affect your projects—and what you can do to extend the life of your moulds.
Why Does Shrinkage Occur in Silicone Rubber Moulds?
Silicone rubber, especially platinum-cured types like “Pure Mould”, is formulated to minimise shrinkage. However, minor shrinkage can still happen, primarily during the initial cure or in larger castings where slight dimensional changes may be amplified. Causes may include using incorrect mixing ratios, under-mixing, or insufficient curing time. Following the recommended 1:1 mixing ratio and ensuring a complete cure help reduce this effect.
Durability and Repeated Use
High-quality silicone rubbers are engineered for multiple casting cycles. Over time, continuous flexing, exposure to harsh casting resins, or rough demoulding can gradually wear on the mould, but general use with appropriate materials results in long service lives. Durable moulds like those made from “Pure Mould” or “Liquid Mould” maintain their flexibility and detail, supporting professional and hobbyist work alike.
Tips to Extend Mould Life
- Mix components thoroughly and in the recommended ratio to avoid weak spots or inconsistent curing.
- Allow full curing before first use to ensure optimal strength.
- Handle cured moulds gently when demoulding, especially with intricate details or undercuts.
- If casting abrasive or exothermic materials, monitor your process to avoid unnecessary stress on the mould.
When This Matters
Shrinkage and long-term mould integrity are particularly important for creators casting multiples, producing prototypes, or working with materials where repeatable accuracy is critical.
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Understanding shrinkage and durability helps you select the right two-component silicone rubber and adopt processes that protect your mould investment. For further insights and reviews of suitable products, see our main overview on two-component silicone rubber for mould making.