Is a Release Agent Necessary for Polyurethane Casting in Silicone Moulds?

← Back to how to create a resin mould for polyurethane

Whether you are new to mould making or an experienced caster, you may wonder if applying a release agent is really necessary when casting polyurethane in silicone moulds. While silicone generally has non-stick properties, using a suitable release wax still offers important advantages for successful and repeatable results.

Why Use a Release Agent with Silicone Moulds?

Silicone moulds are prized for their flexibility and natural non-stick finish. However, repeated casting of polyurethane often leads to gradual adhesion, which can cause sticking and deterioration of the mould’s surface over time. A quality release wax, such as Global A2 Release Wax, forms a fine barrier, helping preserve fine details, prevent unwanted bonding, and extend the working life of your moulds.

How to Apply Release Wax for Polyurethane Casting

Before pouring your polyurethane resin, ensure your silicone mould is clean and fully dry. Apply the release wax either by brush or spray, spreading a thin, even layer across all internal surfaces. Let the wax dry for 2–3 minutes—products like Global A2 are formulated to cure quickly—before introducing the casting resin. Regular application before each casting session will help maintain mould performance and improve demoulding ease.

When This Matters: Protecting Your Mould Investment

A release agent becomes essential if you plan to reuse your silicone mould for multiple polyurethane castings, especially for intricate or detailed designs. It minimises the risk of tearing, preserves surface quality, and helps you achieve clean cast releases every time—a key consideration for hobbyists and professionals alike.

Related products

• "Global A2" – Release Wax for Epoxy and Resin Moulds, Liquid, Heat Resistant to 180°C
• "Pure Mould" – Translucent Liquid Silicone Rubber for Mould Making

Related guides

• How To Create A Resin Mould For Polyurethane

Using a quality release agent is a simple step that will enhance both the quality and lifespan of your silicone moulds for polyurethane casting. When learning how to create a resin mould for polyurethane, this small precaution offers valuable peace of mind and reliable results for every project.