Tech Tip: Let’s talk Catalyst

Catalyst is an essential element to most processes in our business. Without the catalyst, no chemical reaction takes place and you might as well just pour water over your fiberglass or table. You would think catalyst would be an easy product to work with, and sometimes you are right, but you have to follow the directions exactly. It’s not pretty when you don’t (trust me).

catalystMEK-P or Methyl Ethyl Keytone Peroxide, not to be confused with Methyl Ethyl Ketone, a solvent, MEK-P is one of the most common catalysts. MEK-P is used for polyster and vinylester style resins. It is very specific on ratios and requires the most attention.

Vinylesters require a hotter catalyst we sell, called Norox 925, sometimes referred to as “High-Point 90.” It’s a hotter catalyst that works better for the Vinylester. You will also see Vinylester requires a ratio of 2% by volume, as opposed to gelcoats and resin which are closer to 1.5%.

catalyst chart small

Gelcoat and Polyester resin, including Boatyard use a standard catalyst, or the 925 catalyst. These resins only require about 1.5% catalyst and are quite specific on the ratios, especially in hot weather. You will also use the same ratio’s for Polyester-based putty, like our OEM Super Poly Fill, or our gelcoat putty.

B.P.O. or Benzoyl Peroxide is a cream hardener that is used for most Auto Body and Bondo-like putties. It’s a bit easier and more forgiving on the mixture and comes in Red, White and Blue. The ratio is 1-1 oz tube per quart, or a 4 oz tube per gallon.

epoxyEpoxy activators are all proprietary, depending on the product. They range from a 1:1 ratio, like with our Table Top Epoxy, to our standard laminating epoxy allowing a 1:1, 2:1, 3:1, 4:1 and 5:1, allowing for different ratios that effect hardness and gel time. With different ratios, the higher the ratio, the quicker the pot time and the harder the epoxy.


With all these activators, sticking to the ratio is key, so if you were planning on eye-balling it, may I suggest picking up a couple of mixing buckets, or a squeeze bottle and take the guessing out of the equation.

3 thoughts on “Tech Tip: Let’s talk Catalyst

  1. Chuck Norris August 24, 2016 / 1:43 am

    In my field of work we mix a 1to 1 table top epoxy! But sometimes the areas we pour the top of the area sometimes doesn’t go completely off or harden. Only happens a couple of times but what can be done to make it harden or do we scrape off and re pour?? We keep at designated temp at all times in a controlled environment!

    • FGCI August 24, 2016 / 12:13 pm

      Good morning!
      Generally, when there are areas that are soft, it’s a result of not having everything mixed. Maybe use a spatula, instead of a stir stick, or something along those lines. But you want to mix it for at least 3 minutes. If you notice some areas not getting hard as quickly, you can also add a bit of heat from a heat gun to it, which should speed up the curing, as well. Let me know if that helps. If not, please feel free to call me and I can try to help you out!

      FGCI Customer Service
      1-800-272-7890 – Ext. 2416

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s