Primed bumper bar
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I just bought a new bumper bar and it was already primed when a put some reducer on a cloth (same reducer I will use in the paint) the primer did transfer to the cloth. I guess I need to sand the primer remove it altogether and prime with better primer.
If it has transportation primer I usually clean it with soap and water to get any of the plastic mold release off. Next I sand it with P400 on a DA, after that I use a water-borne cleaner that is anti-static. Seal the whole bumper and then paint as normal.
Bumpers don’t normally have a “transportation” primer like metal panels. They’re either primed, or they’re not. If primed then I Prepsol, scuff well, wash and paint. The use of an acrylic primer is common – all reconditionsed bars have it here. No problem, treat as above.
If the bumper only has as one part primer, and it washes off with solvent thinner., make sure you don’t soak the cover with too much solvent because it will absorb into the plastic and cause adhesion issues down the road, Strip the primer.; clean with a waterborne. Cleaner, apply a adhesion promotor ; sealer, paint and Clear ANd another thing is if your are using solvent on bare plastic and create static you could go up in flames as well as the shop so be careful
What about use 1K primer I will use De Beer paint and the only De Beer Primer I can find in the store (online store since I have no supplier in my town) are a 1K primer, De Beer epoxi primer could be used at polyester but who do I now what plastic is on the bumper bar.
The other plastic panels I will just put some new paint on them can I just use grey scotch pad and paint. on one panel I have a long scratch so I must put a filler on it can I just sand the filler and on the rest of panel use grey scotch pad and prime the whole panel.When a bar is primed in a factory it’s done properly with correct technology to ensure adhesion between plastic and primer. There is no need to remove the primer and you run the risk of damaging the surface of the plastic, requiring more work to rectify, not to mention that you may or may not have access to the correct products to ensure adhesion.
If it is a 1K primer on there from the factory and you remove it and replace it with another 1K primer you’ve achieved nothing, maybe gone backwards. Every layer that you put on increases the risk of something going wrong and increases thickness which could promote chipping. The factory primer may seem thin but it is thick enough to do its job and still remain flexible.
Really. Just clean it, scuff it and paint it. Job done.
For your other panels, if the paint is sound and in good condition then, yes, Scotchbrite and paint will be fine. Use a scuffing compound with your Scotchbrite to maximise adhesion. Any repaired areas will need to be primed – just those areas. No need to prime the whole panel. This also allows you to blend your colour coat in case the colour match isn’t quite perfect. If the scratch isn’t deep it may just sand out – easier, quicker and possibly better than trying to fill it and having edges to feather.
If it’s an aftermarket bumper cover that has a 1k primer and it washes off easily with solvent than the primer should be washed of and treated as a raw plastic cover for best results, but like I said be careful .
I have decide to remove the 1K primer and use a 2K, I think I sand the bumper bar to remove the primer.
Like others have stated,if its an aftermarket cover just wipe it off with lacquer thiner or sikkens anti static and treat it as a raw plastic cover.If you sand it you will make more work for your self causing the plastic to get “furry” or unnecessary scratches so you will have to prime and resand.Once its bare a good scuuf with a gray scotchbrite with sanding paste,clean with soap and water,adhession promoter,urethane sealer,base,clear,done.
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