andrewharris1031 wrote:where is the black coming from?

Black primer is quite common on silver cars. It helps to make the silver "pop".

To understand how this happened you need to consider that the clearcoat is relatively hard. But, obviously not as hard as even P2000. In sanding you've reduced the thickness of the clear which probably was not visible before you started polishing. Once you hit the spot with the polisher it broke through what was left of the clear.

Basecoat, i.e. the silver, is quite thin and also very soft. So, with a bit of heat generated by the polisher and abrasion from your compound it would have gone in a flash.

The next layer, black primer, is nearly as tough as clear, so that's where the damage stopped.

The consolation is that we've all done it. The knowledge gained and penalty to be paid means that you're less likely to do it again.

A tip: If you can catch your fingernail in a scratch then it's too deep to polish out. Clean it well and apply a little clear touch up paint to seal and take away the whiteness which comes from the bottom of the scratch being uneven and reflecting light differently to the smooth surface.

badsix wrote:its probably a primer coat applied to the aluminum. you sanded or buffed through to that black primer coat. what compound and wheel did you use to do the buffing? looks like an expensive trip to the body shop now.
Jay D.

I hand sanded with 2500 grit paper.... took about 5 minutes until this happened. I'm confused then why the scratch itself isn't black? I just find it hard to believe everywhere around the scratch is sanded too far but the actual scratch is still there completely unchanged. Thoughts?

NFT5 wrote:

andrewharris1031 wrote:where is the black coming from?

Black primer is quite common on silver cars. It helps to make the silver "pop".

To understand how this happened you need to consider that the clearcoat is relatively hard. But, obviously not as hard as even P2000. In sanding you've reduced the thickness of the clear which probably was not visible before you started polishing. Once you hit the spot with the polisher it broke through what was left of the clear.

Basecoat, i.e. the silver, is quite thin and also very soft. So, with a bit of heat generated by the polisher and abrasion from your compound it would have gone in a flash.

The next layer, black primer, is nearly as tough as clear, so that's where the damage stopped.

The consolation is that we've all done it. The knowledge gained and penalty to be paid means that you're less likely to do it again.

A tip: If you can catch your fingernail in a scratch then it's too deep to polish out. Clean it well and apply a little clear touch up paint to seal and take away the whiteness which comes from the bottom of the scratch being uneven and reflecting light differently to the smooth surface.

Thanks so much this was very helpful!