Polyester Resin and Hardener – Mixing Ratio

When laminating with polyester resin, it’s crucial to consider the mixing ratio of polyester resin to hardener. This article explains what is particularly important and how this ratio works.

At a Glance: What is the Mixing Ratio of Polyester Resin and Hardener?

The mixing ratio of polyester resin and hardener doesn’t need to be measured as precisely as epoxy resin. Generally, it is recommended to use 1% to 2.5% hardener, while other manufacturers suggest 2% to 4%. This range allows you to influence the curing time of the polyester resin.

How Does the Mixing Ratio Affect Curing Time?

The hardener ensures that the polyester resin reaches its final hardness after a certain curing time. If you forget the hardener, the laminated surface will never harden or hold. If you use too much hardener, the polyester resin will become very hot and start to smoke as the hardener and resin undergo a chemical reaction. The less hardener you use, the weaker the strength and the longer the chemical reaction will last.

Tip: Temperature is Equally Important

When working with polyester resin, not only the mixing ratio of resin and hardener is important, but also the temperature: ideally, the resin should be processed at around 20°C but at least above 12°C. If the temperature is lower, the resin will not harden. Higher temperatures will accelerate the curing process.