RepairNation.com - Cab Corner Repair Pg 3

Auto: Repairs: Autobody: Rust Repair - Pg. 3

Step 11. Final sand filler
At this point we were satisfied we had a nice flat surface with contours exactly like the original panel had. We finished sanding the filler with 220 grit paper on a DA sander to remove as many sand scratches as possible and to produce a smooth, flat surface for the primer. The smoother it is, and the fewer sand scratches that are in the repaired surface, the less primer that'll be needed to fill the scratches. You can't produce good results painting directly over filler, it needs to be primed first.

Step 12. Feather paint edge
Before we can apply primer, we need to sand the paint up to the point where we'll finish our paint repair (in this case, the lower edge of the two-tone paint line). Then we need to feather the edge where the original paint meets the bare metal so we don't get any visible lines where the paint was ground away. Here we're using a dual-action (DA) sander with 320 grit sandpaper. A hand sanding block or wet/dry sandpaper also works fine.

Step 13. Scuff paint
Primer and paint won't adhere over smooth paint, it'll just flake off. Double-check your work and scuff any unsanded paint with fine sand paper (220 or 320 grit) or use a scuff pad like shown in the picture. Scuff or sand only up to the line where you will finish painting. The fine scratches left behind by the scuff pad or fine sand paper will provide a good surface for the new primer and paint to 'bite' into. Here, we are taking great care to sand only up to the pinstripe.

Step 14. Mask and clean
These next two steps are critical. Take care to mask off the surrounding area with newspaper or masking paper. The pros wipe the paint surface down with a wax and grease remover solution which prevents potential paint problems caused by waxes or oils which may have gotten onto the paint surface at some point in time. It's a good idea to do this even before you begin any repairs. If you don't have any wax and grease remover, you can also use a rag moistened with a spray cleaner like Windex or 409. Don't apply cleaners directly on the filler. They'll absorb the moisture. You don't want that.

Spray primer Step 15. Prime
We first applied two coats of etching primer over the bare metal (same product we used earlier), then two coats of primer over that. Here, we are spraying a high-build urethane primer. High-build primers go on much thicker than spray can primer and doesn't shrink like spray can primer does. After our primer cures, it will be block-sanded to further reduce sand scratches and high/low spots and produce a nice, smooth surface for the paint. Sanding the primer helps make an undetectable repair.

Mask repair For small spot repair jobs like the one we're doing, you can achieve good results using spray can primer. Apply in several light coats. It's a good idea to let spray can primer dry for a couple days before sanding it to allow the thinners to fully come out. Spray can primer shrinks so you want it to shrink before sanding it to minimize sandscratches from appearing after it has been painted.

The next section details how to sand the primer perfectly smooth like a pro.

Sand & paint

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