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 Post subject: Copper-Germanium alloy
PostPosted: Thu Sep 07, 2017 8:35 pm 
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To get the knack of cutting out shapes with the jewellers saw, I bought some copper sheet. While silver is not expensive per se, the copper is cheaper again and I can experiment and make mistakes for little cost. When I'm confident of my ability to cut out more intricate shapes accurately, I'll move on to silver sheet.

Unlike the silver ring bands which soldered cleanly and easily, I had trouble soldering copper at first. It forms the most unbelievably thick oxidization when heated, almost like a layer of burnt paper and I guess it was the thick, rapidly-forming oxide that interfered with the solder flowing properly. Anyway, I seem to have found the secret to soldering it, lots of flux and heat as quick as possible. I'm now successfully soldering copper to copper with easy silver solder (I'm ordering some copper solder) and also succeeded in solder fine a fine silver bezel to the copper, setting a little chrysophrase cabochon into it.

I understand that the surface lustre of the metal won't last as copper oxidises more rapidly and more heavily than silver, but I have plenty of my own cabs I can sacrifice in the name of learning.

I thought "what a shame it won't last - copper really is a beautiful looking metal when it's polished up and contrasts with blue and green stones particularly well". Then I noticed that the silver merchant I have bought the silver and copper from also lists a product called "Copper-Germanium alloy" though they currently have none in stock.

I'm guessing that the premise is the same as for Argentium silver - the Germanium is supposed to protect the metal against tarnishing for an extended period of time?

Does anyone here know much about this alloy?


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Thu Sep 07, 2017 11:50 pm 
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Dunno anything about the alloy (aerium copper?), but I wonder why you had trouble soldering copper. Copper solders (either soft solder or hard solder) very easily with the proper flux. Plumbers and electricians do it routinely :-)

Don't dismiss copper for jewelry. Some value the patina enough to artificially accelerate it.


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Fri Sep 08, 2017 3:39 am 
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AlBalmer wrote:
Dunno anything about the alloy (aerium copper?), but I wonder why you had trouble soldering copper. Copper solders (either soft solder or hard solder) very easily with the proper flux. Plumbers and electricians do it routinely :-)

Don't dismiss copper for jewelry. Some value the patina enough to artificially accelerate it.


Possibly because I approached it in a way that worked for silver, which is probably not the same way as a plumber or a sparky would do it. Gently heating the piece well away from the join to be soldered first before moving on, taking my time. The silver only seems to develop a bit of a black smudge from that - but the copper seems to oxidise so heavily so quickly that the solder won't flow.

Never seen a plumber do it but I suspect they probably drown the area in flux and then blast it with a torch that puts out a flame more like a rocket engine than the little torches often used for jewellery work - I don't think the aesthetics of the join are the foremost thing in the plumbers mind :) Just a good, solid, impermeable join. So I was approaching it with the "cabinet makers don't use chainsaws" mentality. A thick glob of solder may be ok on a pipe join but the join is supposed to be basically invisible on a jewellery piece.

As luck would have it, I also happened to have one of those rocket engine nozzles. I gave the area a good drink of flux and put the piece up on a rack and heated it quickly with a large, hot flame from beneath, figuring that hitting the soldering area directly with the flame would only cause it to oxidise faster. It seems to work well and the solder flowed easily and formed a solid join.

Agree that copper is valuable not just for practice but in jewellery itself. My only concern was that it oxidises quickly. As you say, the oxidised metal itself can look striking and is often done deliberately. But I've come to this through prospecting and lapidary and thus most of my work will probably incorporate stones. I think the stones probably look better with a highly polished metal setting.


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Fri Sep 08, 2017 10:16 am 
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You'd be surprised. Many plumbers take pride in a smooth joint using minimum solder. A thick gob of solder is an indication of a bad joint, probably because of insufficient heating. The size of the flame depends on how big a heat sink has to be brought up to temperature. In electronics, low-wattage irons are used with far less heat output than a jeweler's torch. If there's water left in a pipe, even a big torch will struggle.

Playing the flame directly on a joint will work, but it's better to heat a bit away from the join so you can see the solder flowing in by capillary action.

Believe it or not, many years ago I spent a week in NYC at a "solder engineering" seminar. Learned all about wetting angles and such.


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Fri Sep 08, 2017 2:33 pm 
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Actually, searching around a bit it seems the problem I had is not uncommon. People trying to solder copper in jewellery work reporting the same thing - the solder won't flow. Some people saying that their jewellery making teacher advised them to avoid copper and brass because of soldering difficulties.

Seems there are some important differences between industrial/commercial soldering and jewellery work, even with the same metal.

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You'd be surprised. Many plumbers take pride in a smooth joint using minimum solder. A thick gob of solder is an indication of a bad joint, probably because of insufficient heating.


I don't doubt it. Though the minimum of solder I've seen on a typical copper pipe joint far exceeds the maximum used in jewellery making because the joint is supposed to be basically invisible.

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In electronics, low-wattage irons are used with far less heat output than a jeweler's torch. I


Yep, but I haven't noticed that low-wattage soldering irons get a mention as an important part of a bench jewellers tool kit. I assume they're not up to the task, at least no one has told me they use one instead of a torch - something designed for joining the ends of two little copper wires with a tiny glob of low-temp solder probably isn't much good for getting solder flowing through a join between two bits of metal and I don't think a soldering iron would cause copper wire to rapidly oxidise like a flame does. They seem like two very different things and I'm guessing there's a good reason that the electronics repairman doesn't take a mother board, blast it with a flame and then dunk it in a pickle bath :)

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Believe it or not, many years ago I spent a week in NYC at a "solder engineering" seminar. Learned all about wetting angles and such.


I believe it - I assume that was soldering for industrial application? Do you make copper jewellery? If you've got any tips I'd love to hear them. It seems like soldering pipe fittings is going to be different to soldering pieces of metal that are small, thin and delicate but nonetheless require the heat of a flame for success. I'm all ears for any helpful info you want to throw my way but in my (very limited thus far) experience, soldering small and delicate bits of sterling silver together seems much easier than soldering the same size bits of copper - the two metals just don't seem to react to being heated in exactly the same way.


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Fri Sep 08, 2017 3:24 pm 
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Yep, this is what has worked for me so far....

Quote:
Soldering copper can be tricky. I solder a lot of copper. Sometimes
I use copper on copper and sometimes I solder it onto silver. I have
a few suggestions that have worked for me over many years of playing
with fire. Try this.

1) Flux the copper with LOTS of flux. Copper is notorious for forming
fire scale. Flux often burns off before the copper has reached solder
temperature so be sure you are using the proper flux.

2) Copper solders at an alarmingly bright red color! Don't get scared
and pull the flame away too soon thinking you are close to melting
the project. You aren't. If you pull the flame away, you allow air
to get to the copper and you get nasty scaling and peeling as well as
cooling of the piece.

3) Use a big, loud, hot flame. Don't feather the flame over the piece
to warm it up first. Don't mamby-pamby around with it; get in there
and cook it! Engulf the well fluxed piece in the flame at once. The
technique is = totally against what you were taught in jewelry
school. The idea is to keep the air away from the copper and get it
up to that "scary red" ASAP. You must be really brave and commit
yourself to soldering that thing when

you first touch the flame to it. Put it in water before you put it
in the acid. It will probably have some flakes on it and you don't
want that junk in the acid pot. This technique always works for me.
Hope you have success with it too.

Susan Maxon
Honors Gran Jewelry
Palm Harbor, Florida

https://orchid.ganoksin.com/t/soldering-copper/15709/41

I almost did pull the torch away when the copper began to glow bright red. But I kept it there and it soldered succesfully (if extremely "dirty" compared to silver).


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Sat Sep 09, 2017 11:30 am 
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I think that the problem we have here is that we are talking at cross purposes. Jewellery soldering and plumbing/electronic soldering are two completely different processes. Jewellery soldering uses a "hard" solder (melting point about 600/700 degrees C. and silver based), plumbing and electronic soldering is done with a "soft" (lead based) solder, melting point about 200/250 degrees C. Silver soldering copper is easy enough, IF you use enough flux, lead solder is best avoided like the plague in jewellery work.


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Sat Sep 09, 2017 12:20 pm 
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Lead-containing solder for plumbing is illegal in the US. Lead-containing solder in most consumer products is prohibited in the EU, and discouraged in the US. You're right that primarily low melting point (soft) solders are used in electronic, especially for wave soldering, where components may be at risk. Plumbing often uses silver-containing "hard" solder with melting points over 450C. Eutectic alloys are preferred because they flow more smoothly. BTW, copper is OK at a dull red, but if it starts getting orange, back off :-)


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Sat Sep 09, 2017 2:04 pm 
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Perhaps I should change the recommendation to "avoid all soft solders like the plague". Whatever the constituents, they will do your jewellery no good at all.


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Sat Sep 09, 2017 2:12 pm 
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Actually, using copper for practice seems to me to be missing the point. Using copper, if it works well you have a piece of cheap jewellery, if it goes badly you have a piece of scrap of no value. Using silver, if it works well you have a piece of good quality jewellery, if it goes badly you have a valuable piece of scrap that can be melted and cast into a reuseable form with little effort.


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 Post subject: Re: Copper-Germanium alloy
PostPosted: Sat Sep 09, 2017 11:06 pm 
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I taught jewelry making for many years. I always started my students off soldering copper. Using silver solder, of course. I have never found it significantly more difficult to solder than silver and, you can't accidentally melt it like silver. As others have mentioned, soft solders, lead based or otherwise, have no business being anywhere near a jewelry bench. If one minute speck comes into contact with silver or gold at soldering temps a inordinately large pit will form. Also, be careful with casting with your failed silver soldering attempts. Solder will often cause pitting in the cast piece. It is best to trim off all soldered areas and save it up for the refinery.

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 Post subject: Re: Copper-Germanium alloy
PostPosted: Sun Sep 10, 2017 6:54 pm 
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allen wrote:
I taught jewelry making for many years. I always started my students off soldering copper. Using silver solder, of course. I have never found it significantly more difficult to solder than silver and, you can't accidentally melt it like silver. As others have mentioned, soft solders, lead based or otherwise, have no business being anywhere near a jewelry bench. If one minute speck comes into contact with silver or gold at soldering temps a inordinately large pit will form. Also, be careful with casting with your failed silver soldering attempts. Solder will often cause pitting in the cast piece. It is best to trim off all soldered areas and save it up for the refinery.


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