New urethane bumper cleaning question

2

242 Motorsports

New urethane bumper from Classic Industries for 1979 Trans Am.

Very slick from mold release.

How do I clean before I begin prep?

Dawn? Comet? Purple Power? Bake it in the sun??
 
Most paint makers offer cleaners and a "prep paste" to be used with Scotchbrite pads and water. The system we use here at the shop is to first wash the part with a strong soapy Dawn solution, then dry and wipe down with SPI waterborne W&G remover. Then we use Presta Scuff Stuff paste on a gold or white Scotchbrite pad, scrubbing really well until there is a uniform dull fine scratch pattern, then dry with clean wipes. At that point the part is ready for another wipe down with waterborne prior to priming.
 
Dawn done. Will do again with stronger solution of Dawn and red Scotchbtite.
SPI WB W&G in stock.
I have no paste.

How crutial is the paste vs. Scotchbrite without paste??
 
It's been years since I prepped a bare bumper without prep paste, but back in the Stone Age we used Comet.

Don't know if it will work because in might not be the same as 25 years ago.
 
Oddly enough, I used Comet and Dawn on the advise of the painter who does my fleet work.
After a few scrubs, it has a uniform dull color.

After more cleaning (I'm paranoid of contamination) I'll use WB W&G then Bulldog aerosol adpro before the SPI epoxy primer.

Any other suggestions??
 
Yeah, DON'T use the Bulldog. If the bumper is Endura or urethane, it is not necessary and will in fact provide less adhesion than epoxy alone.

If the bumper is TPO or PP, you'd be far better off using SPI adpro 600-4.

It's not clear to me what material you'd be dealing with on a repro part, but the original bumper materials on a '79 would not require adpro.
 
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