Should I Use a Release Agent for My Mould?

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Wondering whether a release agent is necessary for your resin mould? The right choice can make a big difference to the ease of demoulding and the quality of your final casts. Here’s what you need to know.

When is a release agent needed?

Release agents prevent resin from sticking to your mould, especially if it’s made from porous or textured materials. Surfaces like untreated wood, plaster, or even certain 3D-printed forms often benefit from a light coating of release agent to ensure a smooth release. For non-porous materials such as quality silicone rubber, a release agent is usually not required, as these surfaces are naturally non-stick and flexible.

How to select and use a release agent

If you’re moulding with porous materials, opt for a release spray or liquid specifically intended for resin casting. Always apply an even, thin layer and allow it to dry, following the manufacturer’s advice. For those using robust silicone moulds such as the “Pure Mould” silicone rubber, the addition of a release agent is rarely needed. However, in complex or intricate shapes, a minimal amount can still aid in prolonging mould life and ensuring easy demoulding.

Practical tips for successful demoulding

Always clean your mould thoroughly before and after use to prevent residue build-up.
If demoulding is difficult, gently flex the mould to help release the piece instead of forcing it out.
For repeated casting, monitor for wear and occasionally reapply release agent as needed with more textured or older moulds.

When this matters most

Using a release agent is especially important if you notice any sticking issues with your mould or if your cast pieces have delicate, detailed edges that could tear upon removal. It can also help extend the life of both custom and store-bought moulds.

Related guides

How To Create A Mould For Resin

Choosing whether to use a release agent depends on your mould material and casting needs. For more guidance on making your own mould and working with resin, explore our full guide on how to create a mould for resin.