MEKP is the catalyst (hardener) needed to cure polyester and vinyl ester resins. MEKP is also used with gel coats. It is a solution of methyl ethyl ketone peroxides and cumyl hydroperoxide in phlegmatizer. It is meant for a room temperature cure. It is typically used between 1.25% to 1.75% (1 2/3 ounce to 2 1/3 ounces per gallon). Resins that have Duratec in their name require a 2% mix ratio (2 2/3 ounces per gallon).