Catalyst Used For Hardening All Polyester Resins, Gelcoats, And Putties. It Is A Peroxide With Medium Cross-Linking Actiity, So It Can Be Used In Most Cycles With Temperatures Ranging From 15 To 80 Degrees Celsius. The Recommended Usage Concentration Is Between 1% And 2% By Weight Of The Polyester Resin, Gelcoat, Putty.