Tips on how to prep plastic bumper for re-spray?

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This topic contains 1 reply, has 2 voices, and was last updated by  Chris 3 years ago.

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    Hi there was hoping someone could give me a basic procedure on how I should prep a front bumper for a re-spray. I recently picked up a bumper from a salvage yard to replace a damaged bumper and want to get it ready for paint (It’s going from black to a dark grey color).

    The salvage bumper is in excellent condition with no damage/cracks/scuffs, etc. and only normal pitting/marks from 7 years of road debris. The paint is original factory paint.

    Most how-tos out there cover repairing damage and feathering new paint into old paint but not many cover a simple prep and respray of an entire bumper.

    My main questions are:
    1. What grit sandpaper should I use?

    2. Should I sand by hand or with a DA sander?

    3. I assume the goal is just to mark up the surface and give new primer/paint a good surface to adhere to and not remove the original clearcoat/paint?

    4. any other tips/tricks for prep?

    Thanks for any help on this!



    If it’s pitted with stone chips then I sand back to plastic on those areas. Don’t go coarser than P180 dry and finish off with P320. You can use a DA if the shape permits, but be careful not to change the shape. Using an adhesion promoter over bare plastic is a good procedure but, if sanded to P320, not essential. Use a 2K primer to cover all areas where you have sanded through the original clear, then sand your primer down to P800 wet or P600 if you’re painting a solid colour.

    Where the paint is in good condition a light but thorough and even sanding with P800 will give enough ‘key’, or you can use grey Scotchbrite and a suitable scuffing paste.

    Don’t forget to wash first and then Prepsol well before you do anything else. I like to wash again before priming to make sure all dust and any hand/fingerprints are gone. Dry with a clean cloth and then blow well with air to get rid of any water in corners, crevices, joins etc. Tack carefully before painting.

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