Wikipedia; Concentrated Methyl Ethyl Ketone Peroxide (MEKP) is an organic peroxide, a high explosive similar to acetone peroxide. MEKP is a colorless, oily liquid whereas acetone peroxide is a white powder at STP; MEKP is slightly less sensitive to shock and temperature, and more stable in storage. MEKP is a severe skin irritant and can cause progressive corrosive damage or blindness. Dilute solutions of 30 to 60% MEKP are used in industry and by hobbyists as the catalyst which initiates the crosslinking of unsaturated polyester resins used in glass-reinforced plastics, and castings. For this application, our MEKP is dissolved in dimethyl phthalate, cyclohexane peroxide, or diallyl phthalate to reduce sensitivity to shock. Benzoyl peroxide (Perkadox CH-50) can be used for the same purpose. The standard ratio is 1 oz. MEKP to 1 gallon of polyester resin. For smaller quantities, please refer to the ratios below. Because there are numerous factors that govern the cure rate of the resin, the ratios listed are suggested starting points only. Always do a test with a small amount of resin first before mixing up a larger batch. INFO( 16 oz resin: 1/8 oz MEKP 32 oz resin: 1/4 oz MEKP 64 oz resin: 1/2 oz MEKP)