Preweld cleaning requires two operations: oil/grease removal and oxide removal. As below, remove oils and greases first, then remove the oxide. Don’t reverse this order. Take the following steps before welding aluminum: 1. Remove oil, grease, and water vapor using an organic solvent such as acetone or a mild alkaline solution like a strong soap. You may also use citrus-based degreasers, but be sure to rinse and dry the part before welding. 2. Remove surface oxides with a stainless steel wire brush (used only for aluminum) or strong alkaline or acid. Many welding suppliers sell oxide-removal solutions in spray or squeeze bottles for local application. Exercise extreme care when handling these solutions, and again, rinse and dry the part before welding. 3. Assemble the joint. If it won't be welded immediately, cover the joint with brown Kraft paper to prevent dirt and grit in the air from getting into the joint. 4. Keep the aluminum dry and at room temperature. 5. Weld within a few days. Clean the joint again if it isn't welded within that time. Good luck!!!