JS-Butanox M-50 is a general purpose methyl ethyl ketone peroxide (MEKP) for the curing of unsaturated polyester resins in the presence of a cobalt accelerator at room and elevated temperatures. The curing system JS-Butanox M-50/cobalt accelerator is particularly suitable for the curing of gelcoat resins, laminating resins, lacquers and castings; moreover the manufacture of light resistant parts may be possible contrary to the curing system benzoyl peroxide/amine accelerator. Practical experience throughout many years has proven that by the guaranteed low water content and the absence of polar compounds in JS-Butanox M-50, this peroxide is very suitable in GRP products for e.g. marine applications.