For any hobbyist or DIY enthusiast, adding additives to your resin or gelcoats can make your life easier. However, it can be confusing to know when or how much to use. In this guide, we will go over the different types of additives available and give you basic instructions on how to add them to your resin or gelcoats with ease.


Pigments are added to resin or gelcoat to give them color. Whether you are looking to create your own colors or color matching your repairs, pigments may be a good option for you. They come in various forms, such as powders, pastes, and liquids. We sell liquid concentrate pigments that are opaque (solid in color). Ideally, you should use pigments specifically made for use with resin or gelcoat, as they are more concentrated and won’t affect the curing process. Gel coats are available in custom colors but if you are looking to color match, a few different pigments may be the better choice.

To add pigment, mix it thoroughly into the resin or gelcoat until the color is even throughout, leaving no streaks. It should be added before the catalyst and is recommended to add at a mix ratio of 6-8% by weight. Start by adding a small amount and gradually add more until you achieve the desired shade. Be careful not to add too much pigment, as it can affect the curing process and weaken the final product.

Surface Seal

A surface seal wax additive is added to a wax-free polyester resin, vinyl ester resin or gelcoat to create a hard, tack free finish. It helps to reduce air sensitivity and inhibition. Surface seal wax rises to the surface as the resin or gel coat is curing and excludes the air from contacting the surface of the curing resin. It is typically used in resin or gel coat that will be the final coat. Waxed resin must be sanded for secondary bonding applications which is why it is recommended for the final coat only.

To add surface seal, mix it thoroughly into the resin or gelcoat until the consistency is even throughout. Add it before the MEKP catalyst. Four ounces surface seal to one gallon resin is the recommended mix ratio. It’s important to note that adding too much surface seal can weaken the final product so do not add more than the recommended amount.

**Surface seal is added to polyester and vinyl ester resins. Epoxy resin cures to a hard finish and surface seal is not needed.

Styrene Monomer

Styrene monomer is added to polyester and vinyl ester resins or gelcoat to give it better flow while spraying with a gel coat spray gun or paint spray gun. It thins the resin or gel coat.

To add styrene monomer, mix it thoroughly into the resin or gelcoat before the MEKP catalyst. It can be added up to 8% by weight of the resin. Be careful not to add too much styrene monomer, as it can affect the properties of the resin or gel coat.

Air Dry Additive

Air dry additives are used in a non-waxed resin or gel coat to create a tack free finish. It adds a super high gloss coating that gives a glass like appearance. It is used as a top coat over resin and gel coats to add depth. It is scratch resistant and clear in color.

Air Dry Super Clear Coat is catalyzed with MEKP at 2% by volume. It is ideal to spray the air dry at an air pressure of 25-40 PSI. Start with a flash coat of 2 mils, wait a couple minutes and then start to build coats of 4 mils per pass waiting approximately five minutes between coats (20 minutes between coats if colder temperatures).


Adding different additives to resin or gelcoats can be a good way to ease the entire process. However, it’s important to use the right type and amount of additives to ensure the final product is strong and long-lasting. By following the steps outlined in this guide, you can add pigments, surface seal, styrene monomer, and air dry with confidence and achieve the desired result.

By Dallin Leach 0 comment


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