U-POL Power Can Grey Weld Through Primer 500ml Aerosol. This U-POL Weld Through Primer is a 1K copper-rich weld through primer applied for rust protection around spot, MIG and TIG welding applications. It contains high purity copper metal giving excellent conductivity as well as high adhesion to metals. It also gives a durable semi flexible metallic finish which leaves a corrosion resistant layer to the surface. The Power Can range feature powerful, pressurized spray cans. They are clog free and leave a good spray gun finish. Extremely fast drying.