For most resins, add 2% by weight, i.e. 1kg of resin requires 20g of Catalyst (based on room temperature). Alternatively, use our Materials Quantity Calculator For Clear Casting Resin the catalyst addition is 1%.
For colder conditions, more catalyst may need to be mixed into the resin to ensure a cure. In the winter months, our Roofing Kits will increase from 2% catalyst addition to 3%. Likewise, in warmer climates, less catalyst may be needed (or smaller batches mixed) as warmer temperatures will decrease the working times of your resin.