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Ask the Expert Question-and-Answer Archive by Ron Joseph April, 2007 Aluminum Siding Q: We have restored an old buiding, (1864). We are now in the process of handling the outside of the building. Can aluminum siding be successfully painted. We know preperation is key, our biggest concern is do we prime, do we use oil base products, please help us. I know that I am asking the best person and really need your advise on what products to use. Thank you so very much in advance for your help A: From you e-mail it appears that the existing building already has aluminum siding that you now want to repaint. If the existing finish is still in good condition you simply need to hose it down to remove all oil, grease, dust and other contaminants. Lightly sand the surfaces to a uniform finish, and then apply and an acrylic latex primer and topcoat. The more difficult problem arises if the existing coating is in poor condition and needs to be removed. In that case you will need to decide how best to remove the coating back to keep the bare aluminum. You can consider chemical paint removers that can be purchased in a hardware store, or you can consider abrasive blasting the old paint until you expose the aluminum. In the latter case I strongly suggest that you contact a contractor who has the equipment and experience to do the job safely and without polluting the environment with dust and paint chips. Once the paint has been removed, you should thoroughly wash the aluminum siding with clean water, preferably with deionized or distilled water that you can purchase from a water store. Allow the surfaces to dry and immediately apply a pretreatment chemical. A few pretreatment chemicals can be applied by hand prior to the application of the primer/topcoat system. For the most part, the chemicals are not available from hardware stores, but must be purchased from chemical manufacturers such as Pantheon Chemicals. In particular I suggest hat you consider their PreKote that has already gone through some extensive testing. You can find Pantheon's contact details on the Internet. Application of a pretreatment chemical is critical to the long-term adhesion of the paint system. Depending on how much you intend to spend on this project, and your expectation of the coating's chemical and physical performance properties, you can consider an acrylic latex primer and topcoat formulated for exterior exposure. At the other end of the scale you can select a more sophisticated system comprising an epoxy primer followed by an acrylic topcoat. I have had success with Ameron's If you are an amateur at painting and do not have the proper application equipment, I suggest that your safest bet is to go with the acrylic latex system. On the other hand, if you're looking for a high quality, high performance finish the epoxy/acrylic system should be considered. For this option I strongly suggest that you consult with a commercial painting contractor who has experienced in this field. Since I haven't seen the building, and don't know your objectives, I suggest that you further explore the ideas that I have given you. Please do not go forward with the project until you've actually tried the entire coating system on a small section of siding to determine if it will indeed give you the final finish you desire. Regards, Ron Joseph |