Sanding Aid / Surfacing Wax (Modifier-C)
Wax additive is added to the final layer of gelcoat (without wax) or to the polyester laminating resin (without wax) on the final layer of a wet layup to produce a tack-free surface. When you’re building up the layers in a wet layup application, you don’t want wax in the polyester resin because you want the layers to bond chemically, resulting in a stronger bond. It’s only the final layer that needs wax additive in order to cure. The wax creates an air barrier so the resin can cure to a tack-free state ready for sanding and finishing.
High Quality additive for polyester resins and gel coats
Primarily a mixture of styrene and paraffin, the paraffin floats to the surface sealing air away from the curing polyester
Polyester resins and gel coats will cure all the way through including the surface
Called sanding aid because the surface would be tacky without sanding aid, causing sandpaper to gum-up
Causes Polyester Resins and Gelcoats to Cure on Air Exposed Surface
- Color: Clear
- Bottle size: 1 Gallon.
Directions for Using Wax Additive
This additive contains paraffin and styrene. When adding it to gelcoat, you must also add the MEKP (methyl ethyl ketone peroxide) hardener.
The chart below indicates how much additive to add to wax-free gelcoat or polyester resin. Avoid using too much wax as it will result in fish eye and other undesirable results.
Amount of Gelcoat or Polyester Resin w/o Wax
Quantity of Wax Additive Required
16 oz. (1 pint)
32 oz. (1 quart)
1/2 ounce to 1 ounce
2 ounces to 4 ounces
In temperatures below 70°F, the paraffin component can solidify in the container. To return it to its liquid state, place the container in the sun or in front of a lamp. PLEASE USE CAUTION—WAX ADDITIVE IS FLAMMABLE!