Rock Chip repair [Archive] - Bimmerfest - BMW Forums

: Rock Chip repair

01-24-2002, 08:09 AM
Over the past week I've been repairing some rock chips. I used the process that has been documented many places. In a nutshell:

1) Wash to remove wax.
2) Remove corrosion (if necessary)
3) Prime.
4) Apply many coats of color to build up.
5) Apply clear coat slightly above level of paint
6) Sand level
7) polish & wax.

Well it works! BUT its a royal PITA too. If you do not have patience do not bother. This tested mine and I had to walk away a couple times.

It looks great though, you cannot tell where they were.

Need to know's:

1) Take your time, don't rush.
2) I would not recommend doing more that 1 or 2 at a time (I did 8)
3) Use a fine brush not that one that comes with the touch up paint.
4) Build color up in a few coats and keep them even. I got to where I could apply a drop and let it flow out to fill. Try not to overfill with color.
5) USE 2000 grit sandpaper! I used 800 initially, seemd fine to me. Spent double time sanding with 1000 and 2000 to remove the 800 scratches.
6) When filling with clear you have to overfill but be carefull not to do too much, 2000 grit does not take off a lot at a time, you may be sanding forever to get it level with the rest of the paint.

If you can tolerate it the result is awesome, I cannot tell where they were with the exception of one that had a small airbubble in the color coat, looks like a very small chip.

I'm pleased wit the result but don't know if I'll go through the pain again.


01-24-2002, 08:17 AM
Thks for that post Doug. One of the things I found to be very useful in application is a toothpick.

What type of sand paper did you use?

01-24-2002, 08:25 AM
Just picked up some 3M at a body supply place.
I had been told that it didn't work on new cars because of the thin does! WHAT A PAIN though....did I mention that? (grin)

01-25-2002, 04:26 PM
You also need to mention that the paper should be wet when sanding, and you absolutly have to get sand paper designed for body shop use (wet/dry).

I used to custom paint jetskis and the trick to sanding was wet paper and a light touch. You can sand right through the paint if you are not careful!

I have a ding on the top of my trunk I have to fix, maybe I'll take some photos of the process and add them to my website.

Rather than using a toothpick I have a hobby air brush and may try to air brush the color on, then brush on the clear....

Good post!

01-25-2002, 06:16 PM
Thanks Chipster,
I was not trying to detail the whole process, it has been written up many times, just a overview. Yes wet sanding with the proper type of sandpaper is imperitive. Airbrush sounds like a great way to fill the color. Never had a steady enough hand myself.

01-27-2002, 06:12 AM
It is a PITA! Most mere mortals simply lose patience and "dab" a little paint into the chip. However, the result is far from satisfactory and usually requires MUCh more time to correct.
Simply put, if you don't have the patience to do it correctly, don't even begin.