Spray directly on polystyrene foam (Styrofoam).
Duratec StyroShield Primer is a polyester primer that is meant to be applied directly to polystyrene foam (also known as Styrofoam). When cured, StyroShield forms a barrier that allows the use of conventional polyester laminating resins, gel coat, or other Duratec products. StyroShield contains microspheres that insulate and protect polystyrene foam from the chemicals in polyester-based resins and gel coat. With StyroShield, low-cost polystyrene can be substituted for urethane foam in plug, mold, and pattern building applications. Spray StyroShield using an HVLP gun with a 2.5 mm or larger nozzle. Apply at least 20 mils of StyroShield to ensure complete coverage and surface protection. When in storage, the microspheres in StyroShield will float to the top and form a hard crust. Thorough mixing is required prior to use. When possible, store StyroShield Primer container upside down. Requires 2% MEKP.  

#1040 can be mixed 1:1 with regular gel coat to reduce viscosity, porosity, and permit a complete open air cure. The reduction in viscosity allows gel coat to be sprayed controllably through siphon and HVLP equipment, reducing sanding and polishing time. Below the waterline repairs still need the addition of #71 Styrene Wax for maximum hardness. Requires 2% MEKP. 

Duratec Surfacing Primer is the best choice for coating your plug or reconditioning your mold.Thin 5%-15% if necessary to a desired spray viscosity with #2306 Duratec Thinner after catalyzing. This surface primer can be applied as heavily as 45 mils to fill fabric pores on plugs or over repairs. With a higher heat distortion temperature, shrinkage is reduced. This further hides the repair.The gray primer sands easily and is then buffed to a Class 'A' mirror finish before building the mold. Requires 2% MEKP. 

Enhance the flow and leveling properties of #1041 Duratec Gray Surfacing Primer. This thinner reduces orange peel and porosity while allowing for a smoother spray flow. 

#69 MEKP is required with all Polyester Resins, Gel Coats and Vinyl Ester Resin. It is required in different concentrations as defined for each resin product. Each resin product is available as a kit with the correct amount of hardener. However, hardener may be purchased individually as shown here.