Plywood is thin sheets of wood glued and pressed together. Plywood is used in many ways, from the roofs on our homes to makeshift garage-sale signs. Marine plywood is a type of plywood made with waterproof adhesive and it is usually coated with a waterproof varnish. Marine plywood is mainly used in boats and structures that are exposed to a lot of moisture. The problem with using marine plywood is that it is much more expensive than regular plywood. But with a little time and effort, you can make your own marine plywood by waterproofing less expensive regular plywood.
Lay the plywood flat on the saw horses. Wipe down the surface with a damp cloth rag.
Mix one part polyester resin with four to six parts acetone in the 5-gallon bucket. Add the catalyst (the catalyst comes with the resin) according to the instructions, as if the catalyst were the polyester resin. For example, if the four parts acetone and the one part polyester resin equals a total of 1 gallon, add enough catalyst for 1 gallon of resin.
Apply the polyester resin and acetone solution to the surface and edges of the plywood with a paintbrush. This solution will soak into the wood so don't worry about applying it too thickly.
Mix more of the polyester resin and acetone solution in your bucket, but decrease the acetone amount by one part so that you have a one-to-three parts solution. Also, decrease the amount of catalyst you add to the solution. Apply the solution as instructed in Step 3.
Mix your epoxy resin with the catalyst as instructed by the manufacturer. Once the coat of polyester acetone solution has dried, apply the epoxy resin to the surface and edges of the plywood with a paintbrush. This creates a finish layer over the tacky polyester resin and acetone solution.
Mix your clear enamel paint with a paint stick and then apply it with a paintbrush over the epoxy resin coat after it has dried. Let the wood sit overnight.
Flip your plywood sheet over and repeat Steps 1 through 6 on the opposite side to finish making your marine plywood.
Wear a respirator when applying chemicals to your plywood as they may be harmful when inhaled.