How to mix fiberglass resin & the catalyst

Updated February 21, 2017

In order to apply a fibreglass cloth or mat, or to create a fibreglass mix for a mould, you need to first mix a resin for the material. In the case of fibreglass cloth or mats, the resin acts as a filler material and a strengthener, holding the fibreglass strands together and filling the spaces between the weave to create a waterproof surface. When used with tiny fibreglass strands, the resin mix serves as a carrier and binder, allowing you to pour the strands into a mould where the resin hardens them into the mould's shape. Regardless of how you'll use the resin with your fibreglass, the mixing process of resin-to-catalyst for hardening remains the same.

Pour the resin into a bucket, adding only as much resin as you think you'll be able to use within 15 or 20 minutes. The resin begins to cure immediately after adding a catalyst and after 15 or 20 minutes becomes hardened to the point of unworkability. Keep careful track of how much resin you add to the bucket.

Pour the MEKP hardener or catalyst for the resin into a measuring cup. Add only the amount of resin needed according to the resin manufacturer's mixing instructions to match the amount of resin poured into the bucket. The typical mixing ratio for MEKP is 1 per cent by weight of the resin, which is about 5ml. of catalyst per 454gr. of resin.

Add the catalyst to the bucket of resin. Stir the catalyst into the resin with a wooden stirrer until mixed. You can tell the mixing is complete by a lack of streaking throughout the resin.

Add a colour paste to the resin mixture to tint the resin. The more colour you add to the mix, the greater the colour depth. Mix with the wooden stirrer until the colour is constant throughout the resin.

Things You'll Need

  • Polyester resin
  • MEKP (Methyl Ethyl Ketone Peroxide) hardener
  • Bucket
  • Measuring cup
  • Wooden stirrer
  • Pigment colour paste
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About the Author

Larry Simmons is a freelance writer and expert in the fusion of computer technology and business. He has a B.S. in economics, an M.S. in information systems, an M.S. in communications technology, as well as significant work towards an M.B.A. in finance. He's published several hundred articles with Demand Studios.