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  1. #1
    Senior Member
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    Frame prep before powdercoating

    I had my frame powdercoated about 9 months ago and I just noticed there is a nice long line of rust bubbling up from under the powdercoat on the underside of the top tube. I'm assuming the powdercoater didn't sandblast it adequately or otherwise didn't prep the surface. Does that sound right?

    Is the solution to sandblast (or bead blast), then apply a phosphoric acid based etch and then put powdercoat over that? If not, any recommendations so rust doesn't come through.

    I'm going to go back to the powdercoater to ask him to do it again and I want to make sure he gets it right this time.
    Il faut de l'audace, encore de l'audace, toujours de l'audace

    1980 3Rensho-- 1975 Raleigh Sprite 3spd
    1990s Raleigh M20 MTB--2007 Windsor Hour (track)
    1988 Ducati 750 F1

  2. #2
    Senior Member
    Join Date
    Oct 2007
    Location
    SE, Michigan
    My Bikes
    k2 Zed 3.0
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    Quote Originally Posted by San Rensho View Post
    Is the solution to sandblast (or bead blast), then apply a phosphoric acid based etch and then put powdercoat over that? If not, any recommendations so rust doesn't come through.
    I believe oxalic acid is preferred over phosphoric acid for rust removal.

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