Bubbling Rear Bumper Paint | FerrariChat

Bubbling Rear Bumper Paint

Discussion in '308/328' started by Martin308GTB, Oct 21, 2018.

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  1. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
    Full Name:
    Martin N.
    Hello together,

    I plan to repaint my rear bumper this coming winter. Painted eighteen years ago. Perfect for ten years. Then slowly some bubbles began to appear under the paint. Not overall. But a few spots. Now it's gotten so bad, that I will repaint the bumper. Not, that it's a big problem for me painting every ten to twenty years :) But I'm curious, what happened here. It's not above the exhaust tips. So I cannot suspect heat.
    Any ideas?

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    Best from Germany and thanks in advance
    Martin
     
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  2. Crowndog

    Crowndog F1 Veteran
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    Jul 16, 2011
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    Fairfield,Pa
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    Robert
    #2 Crowndog, Oct 21, 2018
    Last edited: Oct 21, 2018
    Have you popped open a bubble to see what is under it? Some things that cause bubbles are usually from prep not done right before painting. Is there rust under the bubbles or powdery substance or nothing?
     
  3. Crowndog

    Crowndog F1 Veteran
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    Robert
  4. Crowndog

    Crowndog F1 Veteran
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  5. Schulz308

    Schulz308 Formula 3
    Silver Subscribed

    May 21, 2014
    1,450
    STL USA
    It most likely bubbled up because oxygen was trapped under the finish.
     
  6. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
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    Martin N.
    Are US-bumpers steel? Then I forgot to mention, it's of course GRP. I suspect something outgassing.
    What still makes me wonder, why it didn't occur for ten years after painting and then suddenly occured.

    Best Regards
    Martin
     
  7. Crowndog

    Crowndog F1 Veteran
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    I believe that US bumpers are steel which is why many replace them for the lighter plastic ones. I did and moved them in like the Euro cars. Of course it took ten years because of global warming.
     
  8. scowman

    scowman Formula 3

    Mar 25, 2014
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    Stu Boogie
  9. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
    Full Name:
    Martin N.
    Thanks. But since flexibility of our bumpers is somehow limited, I think flexible paint is over the top. I will stick with my old procedure. Plastic primer, filler, basecoat and semi-matte clearcoat with a small amount of plasticizer.
    Meanwhile I have opened a bubble. They are probably caused by a adhesion problem between filler and basecoat. I will sand the filler more carefully next time.

    Best from Germany
    Martin
     
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