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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Wash, Wax, Detailing and Cosmetic protection/repairs > Advice needed for bumper scratch repair



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      09-30-2012, 08:40 PM   #1
Brian911
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Advice needed for bumper scratch repair

I have an used bumper sitting in my living room destined for my car. Before I put it on to replace my even worst off bumper, I want to fix as much of the scratches as possible.

I have the following products:

ScratchX 2.0
BMW black sapphire metallic touch-up paint
BMW clear coat touch-up paint
180 and 1500grit sandpaper
Bondo Easy Finish Black Flexible Bumper Repair

I wet sanded some light scratches out, but after polishing out the area with ScratchX, the paint appeared significantly lighter under a bright light. Did I go through the clear? How do you tell?

My next experiment will be to fill in the lighter scratch with clear coat paint, and sand level/polish. If that doesn't work, I may try out the Quixx Paint Scratch Remover system.

Also, I noticed that the clear coat on the front of the bumper when seen on an angle is rough and has micro 'pits' that look like it was caused by micro impacts with rocks, but not with sufficient force to chip the paint. It's especially apparent when compared to the protected paint behind the license plate which is basically flawless. Can compounding remove these pits or is a clear coat respray required?

Sorry for all the questions - I'm a DIY'er and a very curious person too!
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      09-30-2012, 09:18 PM   #2
ddas
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ScratchX is not a good candidate for clear coat correction. It's ok at filling minor scratches.

If you are sanding and wanting to polish afterwards, I suggest you work up from 1500 paper to 2k then at least 2.5k(then 3k if you can find it locally). But I bet 2.5k by itself will do for what you are working on. Polishing 1.5k sanding marks by hand will take forever and you probably will not get good results.

If this is your first bumper repair, prepare for it to take a long time and for the results to be less than ideal. There is no substitution for experience. My .02 is you take the bumper to a body shop.

Quixx is actually a pretty good system if you are not looking for body shop-perfect.
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      09-30-2012, 09:37 PM   #3
Brian911
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Since I used ScratchX before to buff out scratches, I thought it could take over at 1500 grit to finish. I guess I'll try sanding at an even higher grit. What should I use to polish?

Getting the whole bumper resprayed when there's only a few problem areas just seems like a waste. First, it's a lot of money and then there's the chance that the paint is not as good, or the color doesn't match.
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      09-30-2012, 09:44 PM   #4
ddas
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Meguiar's 105 will work by hand, albeit time consuming.
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