MEKP Catalyst is a clear, colorless solution of methyl ethyl ketone peroxide in a mixture of dimethyl phthalate and an ester plasticizer. MEKP is principally used as an initiator or catalyst for the room temperature cure of unsaturated polyester and vinyl ester resins. It is also needed with all gel coats. 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).