# adhesion promoter



## charlie20vt (May 8, 2011)

Hi people 

does any one here use adhesion promoter on plastic bumpers 
and would this be used after filler is applied or before filling and after ?

how does everyone else use adhesion promoter 

Thanks 
Charlie a


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## Barbel330 (May 3, 2016)

It's only really needed on raw plastic.


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## squiggs (Oct 19, 2009)

As above (I think?)

If you were painting a raw bumper you'd clean (no sanding required), scotch, clean - and then you'd need to use adhesion promoter.
Most repairs require sanding and that will give the primer something to 'hold onto'.
That said there are times when a scratch in plastic can be sanded out very smooth (and in these cases - right or wrong - maybe belt and braces) but I then give a dusting of promoter before priming.
If you're applying filler then it should be safe to assume that you've only given it a 'rough' sand so that the filler can grip.
Then even after going down through the grades on the filler there should still be enough sanded area to the exposed plastic for your primer to 'get a grip' without the need for promoter.

Finally...promoter is solvent based - solvents will eat into filler and lift the edges of the filler


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