MEKP (also known as methyl ethyl ketone peroxide) is a clear catalyst or hardener for the room temperature cure of unsaturated polyester and vinyl ester resins. These resins must be used with MEKP in order to cure. MEKP is also used with all gel coats including tooling gel coats. It is usually used between 1.25% to 1.75% (1 2/3 ounce to 2 1/3 ounces per gallon). Resins that have the brand name Duratec in them must use a 2% mix ratio (2 2/3 ounces per gallon). MEKP is hazardous and must be handled with care. You can purchase a catalyst dispensers to help you carefully measure and add the amount of MEKP you need. Make sure you wear gloves when handling both MEKP and resin. Included down below are some charts to help you figure out how much MEKP you will need for your project. Remember, it is best to mix in small quantities. Large quantities will exotherm (give off heat) and kick off too fast, leaving you with a mess in your mixing cup.
Catalyst Quantity Charts
CATALYST LARGE QUANTITY CHART
| Catalyst Concentration | Resin Quantity | ||
| Quart | Gallon | 5 Gallon | |
| 1/2% | 1/16 oz | 2/3 oz | 3 1/3 oz |
| 3/4% | 1/4 oz | 1 oz | 5 oz |
| 1% | 1/3 oz | 1 1/3 oz | 6 2/3 oz |
| 1 1/2% | 1/2 oz | 2 oz | 10 oz |
CATALYST SMALL QUANTITY CHART
| Catalyst Concentration | Resin Quantity 30 drops = 1 cc | ||||
| 2 oz | 4 oz | 8 oz | 12 oz | 16 oz | |
| 1/2 % | 9 drops | 18 drops | 36 drops | 1.8 cc | 2.5 cc |
| 3/4 % | 14 drops | 27 drops | 2 cc | 3 cc | 4 cc |
| 1 % | 18 drops | 36 drops | 2.5 cc | 3.75 cc | 5 cc |
| 1 1/2 % | 27 drops | 2 cc | 4 cc | 6 cc | 8 cc |
| 2 % | 36 drops | 2.5 cc | 5 cc | 7.5 cc | 10 cc |