Gamblin Cold Wax Medium Gamblin recommends wax medium to thicken your oil or alkyd paint and to provide a matte finish. Giacomo one of our staff artists prefers to use wax medium to build up translucent layers. He likes the unique surface created by this medium which allows him to juxtapose colors without blending unless blending is desired. This characteristic creates a very unique color field without brush strokes by using a palette knife.