Filler & Sanding
Prior to any filler work or applying primer, be sure to rough all epoxy-coated surfaces with a minimum of 180-grit media to promote adhesion. Adkins started with USC All Metal 14010 and USC Duraglas 24030 from Eastwood for areas that have been patched or welded. These fillers are less likely to absorb moisture. Normal lightweight fillers are basically talc and resin, and talc absorbs moisture readily, the difference being that All Metal is comprised from aluminum particles and resin, and Duraglas is ground fiberglass strands and resin.
Duraglas is also preferred for areas that may need a little thicker application as it is much stronger than a lightweight filler. Adkins uses it to get close, then switches to a lightweight filler that is much easier to sand. Eastwood Contour Premium Body Filler 13520 ZP was used for most of the areas, followed by Eastwood Contour Polyester Glazing Putty 13521 to fill any micro pinholes that are common with lightweight fillers. Remember the smoother and more carefully you apply the fillers, the easier it is to sand and shape. Take care here to save yourself from unnecessary or additional work due to sloppy application.
Once dry, the filler was rough shaped with Norton 36-grit, then finished in 80-grit before applying Metacryl Epoxy primer. Epoxy was chosen to ensure a good bond and corrosion resistance to the existing PCPC powdercoated epoxy primer and seal any raw metal spots exposed during bodywork. Metacryl Epoxy primer (gray) 7396A mixes 1:1 with 7365 Hardener. Adkins applied two medium coats, allowing each to flash 20 minutes before applying Metalux 2K HS Filler Primer 9341 in three coats, allowing 15 minutes flash time between coats. This filler primer mixes 4:1 with 9091 Hardener (fast, there are multiple speeds available for different temperatures). This versatile primer also doubles as the final sealer at a 5:1:1 mix ratio with ChemSpec 1155-222, which conveniently eliminates the need to purchase another product.
Final Block Sanding
After the primer had cured overnight, Adkins used Norton 80-grit for the initial block sanding. Some may cringe at the thought of using such an aggressive paper to start with, but Adkins prefers the faster cut since it makes a car straight in a fraction of the time it would to start with 180-grit. With three coats of the Metalux high-solid primer, there is plenty of material to cut, and follow with 180-grit to smooth out the rough scratches before repriming. Norton Black Powder Guide Coat was used to highlight the low spots, pinholes in the filler, or deep scratch lines that the primer may not have filled. To eliminate them, Eastwood Contour Polyester Glazing Putty was applied and finished with 180-grit prior to re-priming with the ChemSpec 9341 filler primer.
The second round of filler primer gets two medium wet coats, allowing 15 minutes flash time between and at least overnight drying time before blocking again with 220-grit. After the 220-grit, Adkins reapplied the Norton Black Powder Guide Coat and re-sanded with 320-grit. If everything looks good, you are ready to go to the booth. If more work is needed, it's not necessary to re-prime the entire car; just spot prime and repeat the final sanding steps.