Q. I just read your article in the April issue of STREET RODDER. You talked about repairing a '33 Ford truck grille and using "soft solder" for filling scratches, waves, or pits. What type of solder are you talking about—the kind that plumbers use to sweat-solder copper pipe and fittings together? They are using a lead-free type of solder for this now. Are you talking about using an acid core solder? Or, are you talking about using a silver solder that can be bought at a hobby shop, which melts with a propane torch at low temperature?
If any one of these can be used to fill pits, can they be copper plated, and then nickel/chrome plated without any problems? I have a real nice '34 Ford grille with some light pitting on the sides of the bars, and I would like to fill them.
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A. When I say "soft solder," I am making a distinction between solder made from tin and lead, and silver solder, which is stronger, but melts at a much higher temperature, and is much more difficult to file. To confound things even more, there are silver-bearing solders that melt at lower temperatures than traditional silver solder and are not as hard (or expensive).
The old 50/50 acid-core solder that plumbers use is pretty convenient for filling small pits, since the acid helps tin the base metal and aids the adhesion of the solder to the substrate. Fifty/fifty is not the only type of soft solder that could be used, and in fact, I saw a bumper that Darryl Starbird made for his recently finished Cadillac Eldorado Brougham, (see photo) where he did a lot of his signature sculpting with 70/30 lead filler, and it was expertly chrome plated by Advanced Plating in Nashville. The results are striking. Using a large volume of solder like this is tricky, because unless you take extreme care, the heat generated by polishing could melt the solder, so it takes an exceptional plating shop to pull it off.
I'd stay away from the new lead-free solders and sliver solders because their melting temperature is much higher than tin/lead solder, which can lead to more risk of warping on delicate parts like your grille.
All of these solders can be plated, and the preferred method would be to copper plate the pitted or wavy parts first, then fill any defects with solder, sand, or file, and re-plate with copper. These steps often have to be repeated several times to get a top-quality job.
Q. I am working on a '68 Firebird, and both replacement quarter-panels have been brazed on. I would like to know what I can cover the brazed areas with to keep the plastic body filler from cracking?
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A. You may know that I really don't like to use brazing on steel panels that will be painted or finished with plastic filler because I don't believe that these materials adhere properly to brass. Your best bet is to carefully clean the brazed areas, being especially careful to remove all traces of the brazing flux, and then seal the brazed areas with a good-quality epoxy primer-sealer. Once the panels are sealed, you can use the plastic filler on top of the primer.
You can email your questions to Professor hammer at firstname.lastname@example.org, or mail to: Covell Creative Metalworking, 106 Airport Blvd,. Suite 105, Freedom, CA 95019; you'll receive a personal reply. Ron Covell has made many DVDs on metalworking, and he offers an ongoing series or workshops across the nation. Check them out online at covell.biz, or call for a current schedule of workshops and a free catalog of DVDs. Phone (800) 747-4631, or (831) 768-0705. You'll also enjoy Ron's YouTube channel: youtube.com/user/covellron