How to Paint Aluminum Siding

Allen's Blog, Painting & Finishing, Repairs and Installation by Allen Lyle

One common question that Danny and I receive on the radio show is, “Can I paint aluminum siding; and, if so, what is the best method?” Great question.

The key to painting aluminum siding is preparation and priming. All of the chalkiness must be washed and scrubbed off, and any flaking paint removed. In a nutshell, you need to start with a clean palette.

Once everything is clean and dry, you’re ready to apply your primer. Here’s where a lot of people make a mistake and, unfortunately, I’ve even heard of “professional” painters who do this. They apply a latex primer.

This is probably the worst thing you can do when painting aluminum siding. Most latex paint has ammonia in it, and that includes primer. Ammonia has a chemical reaction to aluminum, which produces a tiny amount of gas.

Latex paint, by nature, is very elastic, so you end up with an elastic coating with gas bubbles underneath it. If you don’t quite see the problem here just think about how your own insides react a couple of hours after eating two or three bean burritos . . . ’nuff said, right? The gas build-up under the latex primer pushes up and out, which bubbles and flakes the top coat, in other words, it causes the paint to fail.

The solution is to use an oil-based primer specifically designed for metal surfaces. You will have to wait longer for an oil primer to dry, but it’s better than having to re-do everything within a year or two.

Once the primer is dry, top coat with a 100% acrylic paint. If you take this approach to your aluminum siding paint project, you’ll have a long-lasting finish you can be proud of.

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4 Comments on “How to Paint Aluminum Siding”

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  1. Mario Vespucci Says:
    November 27th, 2009 at 03:26

    This should clear up why aluminum sidings need a long time to prime. Thanks. =)

  2. robert mcdonough Says:
    May 11th, 2010 at 13:39

    I have heard several reliable professional sources recommend the use of a latex paint after using the oil-based primer. Why shouldn’t we use an oil-base exterior paint over the oil-based primer for the best finish and bond? I know the clean-up is harder but the result is tighter and longer-lasting isn’t it?
    Thanks.
    Robert

  3. Official Comment:

    Allen Says:
    May 12th, 2010 at 07:42

    Great question, Robert! I’ll go back to the fact that a lot of “professionals” will also use latex as a primer, and that’s the biggest mistake in my book. But, beyond that, there’s a difference in latex and acrylic latex. Instead of a water base (latex), acrylic is a chemical base. But, the latex properties of the acrylic also mean it’s going to be more forgiving to expansion and contraction. That gives it an advantage over oil top coats. And, unlike oil in an exterior venue, it resists chalking and blistering much better. That doesn’t mean you can’t go to the extra effort of an oil top coat, but for my dime, I think an acrylic latex will provide a better appearance as long as you prep and prime the right way!

  4. Sheila Says:
    May 17th, 2010 at 08:25

    So, do you use an oil base acrylic for your top coat also? since we use an oil base primer.

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