Eastwood After Weld Metal Prep was developed for both pre and post panel prep and cleaning. This aqueous cleaner was designed to clean the bare metal prior to welding to remove contaminants and also be used after welding or grinding to assure a clean panel. After Weld will also properly "etch" the metal with phosphoric acid for excellent primer and paint adhesion. It can be used on steel, cast iron and aluminum. Do not use on chrome plating or polished aluminum.