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Painting aluminum house columns

I have two aluminum columns in the front of my home that I painted over the summer. Now that the cold weather is here they have started to crack and peel right down to the bare aluminum. Could you help me by telling me what I have done wrong? Also can you tell me how to do it right? Do I need to sand down to bare aluminum? Use a special primer/additive? Should I spray or brush it on? I have done this twice over the last two summers. It has peeled and cracked both times when it gets cold.

Thank You

John McGlinn
homeowner - Hatfield, Pennsylvania, USA
2005

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First of two simultaneous responses --

Paint adhesion over aluminum can be a real problem. Manufacturers can apply chromate films to achieve good adhesion, but you can't do this at home. I'd suggest you have to remove all the old paint, then go to an automotive paint supply store and ask them for a primer suitable for aluminum. You may have to spray this - they will tell you how to use it. Once you have the primer on, you can spray or brush - ask the guys at the auto paint store about that too.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2005

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Second of two simultaneous responses --

The paint is cracking due to your columns expanding and shrinking due to changes in the weather, I am gonig to guess that you are using either plain spray paint or a petrol based paint. For starters, sand them down to the bare metal, then you DO need to prime them, then paint. I would suggest an epoxy based paint for the finish (very robust and durable when done properly). Conversely you could pickup some Rustoleum lawn furniture paint (the ones for metal), that would possibly hold up better, but I would still go with my first suggestion.

Marc Banks
- Elizabeth City, NC USA
2005