The isocyanate component (Part B) of a polyurethane system has a freezing point around 20°C. As a result, if it is stored for long periods below this temperature it will crystallise.

It can be re-melted again by warming to around 60°C for 3/4 hour and then stirring.

You must not use it while still warm as this will inevitably lead to extremely short pot life and poor properties. It is essential that once re-melted, the isocyanate is allowed to cool back down to room temperature.

Freezing and re-melting has no adverse affects on the product.