In spite of my desperate (and repeated) attempts, my rust repairs keep rusting. What am I doing wrong?
It's been awhile since I've posted (been enjoying driving the Z instead of talking about her), but I'm experiencing a rust problem that I'm unable to solve. I'm repairing relatively small (mostly surface) patches of surface rust on body panels, but the rust keeps returning.....and often within just a few days of the completion of the repair. In a nutshell, here's what I'm doing (see if you can spot the problem.....PLEASE, I'm getting desperate!!):
1) Grind/sand rust down to bare, rust-free metal.
2) Clear area with denatured alcohol. Let dry.
3) Apply metalized Bondo and let dry (hard) ~30-45 minutes.
4) Sand to shape to body panel.
5) Mask and apply two coats of primer recommended by (and came from) paint company, waiting ~10~15 between coats.
6) Sand surrounding repair area with 180 to blend repair edge to surrounding finish.
7) Apply light glazing layer and, when dry, sand with 400 to smooth/blend.
8) Wet-sand area with 600 to blend and prepare surrounding area to accept base colour coat.
9) Clean with tack cloth.
10) Apply several light layers of base colour coat, waiting ~10~15 between coats.
11) After base colour coat's dry (~45 minutes), wet-sand with 1200 and 1500.
12) Apply two coats of clear coat, waiting ~10~15 minutes between coats.
13) Wait 48 hours and wet-sand with 1200 and 2000, then compound and polish.
When done, the area looks nearly OEM. But within a few days, I'm getting rust bubbling under the paint again. What gives?
Am I doing or using something wrong?