A tough exterior-grade paint costs next to nothing to make from household ingredients. Casein Clear Coat (Makes a lot — you might want to half it) 1 quart room temperature low-fat milk About 4 tablespoons of Borax Reserve about 1/2 cup milk. Mix one tablespoon of Borax (laundry additive) into the remaining milk, stirring with your fingers until it’s absorbed. Keep adding Borax by the tablespoon until the milk stops absorbing it. Then add reserved milk till the last granules disappear.