MEKP Catalyst


This MEKP Catalyst is designed for our polyester resins and gelcoats. Resins are sold with enough catalyst to achieve 1.25% and gelcoats sold with 2%. Extra catalyst is needed in cooler temperatures or for faster drying times.

Please Note: Due to the short shelf life of this product we recommend purchasing only what can be used within 2 months.


MEKP Catalyst (Methyl Ethyl Ketone Peroxide)


MEKP is a clear initiator essential for the curing of polyester resins and gelcoats. It is often called a catalyst but in technical terms, it is actually an initiator. Commonly used in boat building, fiberglass projects, and other resin applications, it ensures a consistent and rapid cure.

Key Features:

  • Consistent Cure: Provides a uniform hardening process for polyester resins.
  • Versatile Use: Suitable for a range of applications including boat building, fiberglass molding, and more.
  • Clear Formulation: Does not alter the color or appearance of the resin.


Clear liquid
Shelf Life:
6 months when stored in a cool, dry place
Reactivity Rate:
Balanced for optimal working time and set time

Usage Instructions:

  1. Ensure the surface is clean and dry before application.
  2. Measure the required amount of MEKP as per the resin manufacturer’s instructions.
  3. Mix thoroughly with the resin until fully blended.
  4. Apply as needed and allow to cure as directed.
  5. Typically, you can increase the amount of MEKP used up to +- 50% to adjust cure time.

Safety Information:

  • Wear protective gloves and eyewear when handling.
  • Use in a well-ventilated area.
  • Avoid contact with skin and eyes.
  • In case of contact, rinse immediately with plenty of water and seek medical advice.
  • Keep out of reach of children.


Store in a cool, dry place away from direct sunlight. Ensure the cap is tightly sealed after use to prevent contamination.

Note: Always refer to the manufacturer’s guidelines for the specific resin you are using to determine the correct MEKP ratio.


More information on Catalysts and Initiators:

MEKP (Methyl Ethyl Ketone Peroxide) is both an initiator and a catalyst. In the context of polymer chemistry, especially for unsaturated polyester resins, MEKP acts as an initiator to start the polymerization reaction. In general terminology, it’s often referred to as a catalyst because it speeds up the reaction without being consumed in the process. However, in the specific context of polyester resin curing, it’s more accurate to call it an initiator.



MEKP Hardener

May 2, 2017

good product

need to sell in quarts for big jobs


MEKP Hardener

June 8, 2015

My last order found that I ran out of hardener, so I ordered this 16oz MEKP. Was surprised to receive four 4oz. bottles, but I appreciate it! Means I don’t have to try to manage a big bottle.

Barton Lone

MEKP Hardener

June 2, 2015

I buy PU resin 5gal and make small resin batches. Inevitably, I end up needing a little additional MEKP before the resin is finished. This is perfect, and a great price. IllStreet customer service is excellent. I don’t even shop around any more, I just click on my shortcut to IllStreet Composites and get what I need.


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