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I wonder if you could expand on this. I was under the impression that brazing over chrome plating wasn't too bad. All the articles I've seen on chrome-6 (hexavalent chromium, a known carcinogen) mention it being created from the intense heat of arc-welding.

I'm definitely not an expert though. If the fumes from brazing on/near chrome are known to be bad, any chance of getting a reference for that? Note I'm not asking you to do my homework for me, just thought I'd ask in case you had that info handy.

I'm all for caution for caution's sake though. Lungs are touchy things, but good to have!

When brazing on repairs where there can be some paint burning, I use a cartridge respirator with cartridges made for organic vapor, with a HEPA filter on top of that. I easily believe that would not be approved for chrome-6. I've heard it said (don't quote me!) that metal fumes are usually in the form of tiny blobs, not a gas but rather a fine particulate, and HEPA is good at taking them out. I've found that to be true for the zinc that boils out of brass ("bronze"), but maybe chrome is a whole 'nother thing. The zinc is not very toxic at low concentrations, so letting a little through won't kill you.

Another thing I've done with chrome is cover it with flux, i.e. what you're doing already. I recently silvered a chainstay housing stop on a chrome "sock", where I removed chrome down to shiny steel only at a tiny dot, the same size as the foot of the braze-on or a little bigger. With an unbroken layer of molten flux over the whole hot area, I can't imagine much fume could be coming through that for me to breathe. Maybe wishful thinking?

I asked my HMO if I could get some test for accumulated heavy metals in my system (cadmium maybe?) but they don't want to pay for the test unless it's ordered by a doc, who'd need to see symptoms I guess. Cheap bastards! I don't even know what tests are available though, maybe they have to biopsy my liver or bone marrow? I sure wouldn't do that out of idle curiosity.

Mark B