How do they do this?

I've been doing some copper art stuff for a while now and I'm constantly
learning. I'd like to learn how to join copper tube/pipe and keep the copper
still shiny. When I braze my joints the resulting joint is dark from the
heat and excess brazing material very often goes where you don't want it. I
have to either use a scotch brite pad in a die grinder or sandblast the
joints to clean them up. Either way, the copper doesn't stay nice and shiny.
If you look at some items from this company in Denver, you'll notice their
tube joints are all very nice looking. I'm sure that they don't spend the
time to repolish. How do they do that?
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especially the 5th through
9th pictures on the page.
Any and all help would be very greatly appreciated.
Lane
Reply to
Lane
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Vat of acid, probably. Referred to as "pickle". Forget the correct type for this, but should be easy to look up. Makes a lot more sense for a factory than for a single person, at least for large work. Some of this work is large enough that I would not immediately jump to the conclusion you have that they don't do a final polish on it. Electropolishing is another possible option.
Controlling excess braze material is a skill; you can also use aids such as yellow ochre to help with that. You can also TIG weld with copper for a perfect color match, but that is also a skill. With skills, practice is the way to get better - Either make and sell a lot of imperfect work, or make and scrap a lot of practice peices - don't practice on your final peice that needs to be perfect.
Reply to
Ecnerwal
I find that "White Out" is good to keep silver brazing where it should be, apply before fluxing. Citric acid (wine making store in bulk) dissolved in water will remove the crud later. 1/4 cup in 2 gals water should do fine. Ok to tip down the drains with a month or two's crud in it. Mike in BC
Reply to
mcgray
When we do refrigeration lines, we purge with nitrogen inside the copper tube, this keeps the copper oxide from forming.
Not sure if that could be done on the outside at the same time you were brazing?? In any sil-phos brazing or silver brazing (not soldering) the copper would still change color from the heat. My guess is the person who said some type of acid pickling or wash has it right. B.G.
Reply to
MachineShop
they probably only flux the flow area and probably use a masking medium so it wont run off. they then probably bath it in some solution, then they buff it, then perhaps clear coat it.
Reply to
Kryptoknight
I think someone mentioned using milk of magnesia as a stop off agent. Google here and in RCM and see if you can find that thread. For a bit more money, your friendly welding store ought to sell stop off.
I just got a flyer from Wall Cromoy with an offer for a free pen of their " green " stop off. You might look at their web site.
Dan
Reply to
dcaster
Google can't find anything when I search on "Wall Cromoy" got another way to spell it? Lane
Reply to
Lane
I never claimed to be able to spell. It is <
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> I found it using " nickel braze wall " They are a leader in high temp brazing.
Dan
Lane (no spam) wrote:
Reply to
dcaster

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