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Thread: Bumper Cover Painting

  1. #1

    Default Bumper Cover Painting

    Was wondering what is the right way to prep aftermarket bumpers
    that come primed.I ve had some peeling problems on a couple of my
    jobs.I usually dry sand(I heard not to wet sand but im not sure)with scuff pad
    ultra fine or 1000 grit,clean and dry,spray adhesion promoter first,and paint.
    I use ppg DBU but should I be adding a flex additive to that.
    Also what is the best way to feather out the peeling section without making it peel further.Wet Sanding?
    Thanks,
    Marc

  2. #2
    Join Date
    Nov 2005
    Location
    Rochester NY
    Posts
    1,372

    Default

    subject comes up often here so if I don't answer it completly you can search on it.

    If the bumper is already primered, then all you need to do is clean it well (wax/silicone remover) and scuff. Then you can shoot. You don't need the adhesion promoter as that's meant for unprimered plastic (in this case).

    I would scuff with something like 600-800 grit wet or dry but go easy since you don't know how much primer is there.

    Topcoats on Bumpers may or may not needed (see P-sheet for the product your using) a Flex-additive but Clear Coats often do.

    If your having a peeling issue it's probaly due to the surface not being prepared properly prior to painting. Either not cleaned well or not abraded correctly.

    You'll need to keep sanding over the area until you get back to where it's good at. So if your sanding and it keeps peeling keep sanding the entire area until there is no more peeling. Otherwise whatever you lay on top will not last for long. See here for a more technical explantion of causes and repair.

    Greg
    Last edited by Roch_Greg; 07-04-2006 at 10:29 PM.
    Thoughts and comments expressed by me are mine based on my own experience and research and shared here freely. I am not a professional nor make any claim to be as such

  3. #3
    Join Date
    Nov 2005
    Posts
    27,970

    Default

    Quote Originally Posted by Cocolroo
    Was wondering what is the right way to prep aftermarket bumpers
    that come primed.I ve had some peeling problems on a couple of my
    jobs.I usually dry sand(I heard not to wet sand but im not sure)with scuff pad
    ultra fine or 1000 grit,clean and dry,spray adhesion promoter first,and paint.
    I use ppg DBU but should I be adding a flex additive to that.
    Also what is the best way to feather out the peeling section without making it peel further.Wet Sanding?
    Thanks,
    Marc
    If the bumper is a "new" aftermarket bumper and the primer is a quality application then I'd just clean, scuff, clean and paint. Most CAPA certified parts are primed well and bare the CAPA label. Inexpensive bumpers can be poorly primed and may need to be stripped and re primed. Usually cheap primer will have runs in it or be flaking when you buy it. Inspect the bumper before you start to see what you have. Applying tape around the edges and pulling it off can help tell you if the primer is going to stay in place after you paint.

    I usually scuff good primer with 400 dry or 600 wet prior to applying base coat color. In most cases you would add flex additive to coatings that get a hardener added. Read the technical info for the products you're spraying to see how they recommend treating the paint for flexible surfaces.

    If the paint is cracking or flaking off of any existing surface it pays to strip it off and start from the plastic substrate. Trying to feather the cracks out of the paint isn't going to help the rest of the paint to stick, it's better to remove it all.

  4. #4
    Join Date
    Nov 2005
    Posts
    1,299

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    In most cases you would add flex additive to coatings that get a hardener added.
    What about not adding the hardener/catalyst/activator?
    I believe the paint will dry eventually, it will just not be as brittle as hardened urathane?
    Will this work?:confused:

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