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Thread: How To Prep Aluminum For Paint

  1. #1
    Join Date
    May 2002
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    Texas
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    Default How To Prep Aluminum For Paint

    I am making a power control box and want to paint it. It is going to be housed in a new aluminum chassis box. I have cut and drilled all the holes, removed the protective plastic film, and it is ready for paint. I plan to use Rustoleum Metallic Gray Hammertone. I have had problems with paint sticking well to these aluminum chassis boxes in the past.



    What is the best way to prepare the surface prior to painting. The can says that primer is not necessary. But is it? Or what? Rough up the surface with sandpaper? Steel wool? What?
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

  2. #2
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    Paul,

    The traditional way of preparing aluminium for further paint coats is to use zinc chromate primer - the yellowy-green stuff. Common on aircraft, and it would probably do the best of all jobs.

    But as this is a power supply, that presumably won't be living its life in constant seawater spray or the like. I'd just scuff the surface with fine emery paper, wipe it with paint thinners and spray the topcoat straight on - maybe a couple of coats. Round off any sharp edges first.

    Ian
    All of the gear, no idea...

  3. #3
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    As Ian B noted Zinc Chromate was the protocol primer for Al. Haven't used it since I got out of the Coast Guard in 72. In those days it was referred to as Green Death!
    John B

  4. #4
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    isn't there some treatment before the zinc Chromate?

    The problem with AL is of course that the surface very quickly oxidizes.....so to get a durable finish on something facing a tough environment is challenged without all specialized chemicals.

    otoh, for light duty stuff, like models, I've just gone ahead and painted it and its lasted beautifully. The photo almost looks to have a coating its so shiny? I would scuff it up and paint.
    .

  5. #5
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    South Wales
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    Default

    I used etch primer from the paint dealer, does the job, probably some acid or some such in it
    Mark

  6. #6

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    As said before Scuff it up good , wash with soap and water and scuff again. Then use self etching primer.

  7. #7
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    Jan 2014
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    Long Island
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    When we painted the mast for my friends sailboat 15 years ago we used something called a "self etching primer" prior to painting. It's held up
    pretty well:

    Whenever you wipe down with solvent make sure you wait long enough for all the solvent to evaporate prior to any spraying or you'll get
    fish eyes in your finish.

  8. #8
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    Feb 2016
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    Johnstown, Ohio
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    etching primer followed by a high solids epoxy based paint

  9. #9
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    May 2016
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    Michigan
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    Default

    That box is a neat job.
    If I could do that I would leave it natural.

    With the bike parts I machine from 6061, some are 2 years old, have been out in winter slush etc,
    and they are still nice and shiny

  10. #10
    Join Date
    Dec 2007
    Location
    Montvale, NJ
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