Mixing Resin

Mixing polyester resin to use with fiberglass cloth is similar to mixing epoxy adhesives. By mixing two compounds a chemical reaction occurs whereby the mixture begins to harden. With resin, a catalyst is used to trigger the compound to begin to harden. The relative speed that the mixture sets up and hardens at can be influenced by the amount of catalyst used. The more catalyst mixed into the resin the faster the batch will set.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Polyester resin
• Catalyst (methyl ethyl ketone peroxide)
• Wide mouthed plastic container
• Wood stir stick
• Gloves
• Eye protection
• Respirator rated for use with polyester resin

1. Assemble all tools, equipment, and supplies for the project at hand and have them easily accessible and ready for use. Everything needed during the use of the resin should be laid out so no time is lost looking for things once the resin and catalyst are mixed and begin to harden.

2. Put on a respirator, eye protection and gloves. Wear long a long sleeved shirt and pants, as well. Tie long hair back to prevent it from getting in the way or smeared with resin.

3. Pour an amount of resin sufficient for the task at hand into a wide mouthed contained. Be sure the container used has a wide enough top opening to allow easy mixing and access to the resin.

4. Add catalyst MEKP (methyl ethyl ketone peroxide) to resin. A general ratio is 10 drops catalyst to every 1 ounce of polyester resin.

5. Mix the two products together thoroughly with a wooden stir stick. Work quickly to achieve a well blended product, but be careful not to mix too fast and cause air bubbles to form in the resin.

6. Prepare small batches of mixed resin and catalyst if you anticipate having to use a large amount of product that will take more than a few minutes to apply, as once the resin and catalyst are mixed the hardening process begins immediately.

Tips & Warnings

• Work in an open, well ventilated area when mixing resin due to the toxic fumes. Use safety goggles, gloves, and a respirator rated for use with resin.
• Use acetone to remove resin from hands--but care should be taken to avoid exposure.
• Polyester resin and the catalyst used along with it are toxic chemicals that can be dangerous if not used properly with care. Keep all sources of flames or heat away from work area, as polyester resin is highly flammable.