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Ask the Expert Question-and-Answer Archive by Ron Joseph October, 2004 Successful Painting of Welded 6000 Series Aluminum Q. Besides powder coating, can I successfully spray paint onto bare welded 6000 series Aluminum tubing. I have read differing reports. The most plausible is an acid wash followed by Metal Prep and then a two part epoxy primer followed by Dupont Imron paint. I had always thought that a dichromate primer should be used. Your thoughts? Yes, the most preferred application procedure is to use an acid or strong alkaline solution to remove any oxidation from the surface of the aluminum prior to the application of any coating. You can sand or mildly abrade the surface to remove any oxidation, but be certain to remove any dust, grease, or oil, prior to, and after sanding. The dichromate wash primers are no longer used due to the contents of heavy metals. They have been replaced with acid etch phosphate wash primers, then followed by the epoxy primer, and two component polyurethane top coats. The wash coat primers are used to promote adhesion of the subsequent coatings. Be certain to follow any and all manufacturers recommendations for surface cleaning and application of these types of coatings. Check with your local specialty paint supplier for any product recommendations that they may have. Please be aware that paints, coatings and solvents are chemicals and therefore you should always pay attention to proper handling procedures and be prepared to wear protective clothing, such as respirators, gloves, coveralls, etc. For further information on the health and safety requirements for the coatings and solvents you wish to use we strongly advised you to contact your local coating supplier. If possible, go the extra step and look for this information on the website of the product vendor. Acid etching: You MUST insure that you are properly protected with goggles, acid-resistant gloves and proper clothing so that you don't injure yourself. For similar reasons, please insure that you keep others away from this process. Regards, Jim Burke
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