I’m building a plug out of a a plywood skeletal frame and I have filled the cavities with 6 pound expandable foam #625 from Fiberglast. I will sand down the foam to my desired shape. My thought is to seal the foam with B un-waxed polyester resin and cloth to create a hard surface over the foam. My question is can I brush on the Duratec primer right over the un-sanded B resin or does it have to be scuffed? I can also spray the Duratec primer with my Accuspray Gun instead of a brush. My thought was to brush the first coat on to build up a decent base, then spray on the last coat that I could sand and polish to a finish and pop off my mold. I’m new to the plug and mold making process and thank you for your guidance and suggestions so the project comes out successful. Allen