I did some rather radical surgery on my front bumper in order to get it reasonably straight and clean (shaved the bumper bolts, etc.) and I'm getting to prep stage before chroming. Unfortunately, there's a bunch of little pits left over, both from old corrosion and the later welding, plus a few dings from a poorly-swung straightening hammer. I'd like to fill most of them before taking the thing to the chrome shop for final plating. What I have in mind is to TIG-braze in either br*** or copper rod, rather than try and weld in steel. Anyone tried this? Is there a more accepted method of filling pits? (That is, larger ones than will be filled with the copper wash of the final plate.) Doc.
i have brazed some parts before chrome and the line between the 2 metals showed back up. I think they may have hit it a little hard with the polish.
Don't use br***! When they strip the old chrome off, it will dissolve. Use steel (mig/tig/ OA). Copper plate will ony fill very minor pits. Pay extra for 'show chrome' it will last longer,but will cost more. Sparky
I already had the chrome stripped off. There's only the nickel and copper left, and I ground that back from where I welded. I was considering br*** or copper braze simply because it would require less heat, and hopefully lead to less warping. Doc.
Have them strip it, copper plate and give it back to you. Fill the pits with true silver solder, absolutely no lead. Most of the platers labor is in removing imperfections after the copper is put on and giving it a show quality polish; so you can save a bunch of money in sweat equity.
Silver solder is correct, I worked at a professional chrome plating shop for years and this is the filler we used, or a good long soak in the copper tank, then sanding, like a "fill primer" for chrome. The best thing to do is to go to your chrome plater and ask them what they want you to do. If they send you home with some silver solder and you can go to work, more power to you. In my experience, the work that people did to their pieces before plating ended up costing them extra, due to mistakes made by people not familiar with the plating process. The shop that is going to plate your bumpers is where you need to go for instructions, they might end up telling you that they want to do their own prep work, and it's best to leave that up to the professionals.
You didn't go into to much detail regarding the bumper bolts but please remember to weld a huge washer for the bumper bracket to snug up to so it's not actually snugging up to the bumper and putting stress on the chrome.
You have to remove the nickel too... That is if the nickel or copper coverage of the steel is not complete. Otherwise the piece will have to stay in the activator tank for some time. The acids will create pits in the steel if it is in there too long. Biggest thing is to make sure you remve any oil or grease from the steel before chroming. Or else it will come out in the plating process. Fill your pits with pure silver solder, no lead. Sand your piece flat to at least 320 grit. If it is going to be coppered leave it at that and the plater will do the rest. If you do not do your sanding and filling properly you will probably double your polishing bill, so make sure you know what you're doing. Copper is not essential on steel if the polishing is good enough. Triple plate is not as rugged as nickel chrome despite what people may say. However, if you have to conceal minor pits and blemishes it is the only way to get a top finish easily. We often braize the welds on harley swing arms to hide those ugly knuckle welds. Braize won't be a problem if you're down to bare steel.
I can attest to that part! After welding the bolts to the front bumper on my '41 Ford PU - NOTE: without the washers to take load off the curvature of the bumper! ** - the shop said, "If you had just left the finishing to us, it would have cost half as much!" ** Without the washers; (that Denise points out) cracks are now appearing where the bolts were welded.
Okay, when you say "silver solder", do you mean true silver braze rod, or just "lead free" solder? Is cadmium content a problem? How can I remove the nickel? Is that something I'll have to do mechancially- IE, sandblast or grind? The shop that stripped the chrome off indicated they either couldn't or wouldn't also strip the nickel. Doc.
By silver solder he means lead free, pure silver. Don't use anything that contains cadmium. Never heard of it in a solder, but if it is exposed to wrong chemicals the fume can be lethal. Plus plating proceedure is difficult on Cadmium. I don't understand why it should be on a bumper.
-I only asked because as I was looking up silver solders and brazes, there were several mentions of cadmium and/or cadmium-free silver solders. I spoke to the plater who recommended normal br*** braze. O/A braze was too dirty and took a lot of gas, so I'm now using copper, TIG-brazed on. It's working well so far. Cleaner to apply than the braze and flux, less heat and warpage, and I have a honkin' big roll of otherwise-useless 14-ga Romex out back that I can get all the filler rod in the world out of. I was also told, as you guys noted, that I have to get all the nickel off. For the flat parts, I found out those 3M "bristle discs" work pretty dang well. I'll probably sandblast corners and recesses to keep from rounding off style lines though. Doc.
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