Anyone do anything with copper?

"Steve B" wrote in news:7XH7h.212$ snipped-for-privacy@newsfe13.phx:

Hi Steve.. Not too much help here I fear pal...I too had the thoughts of using some sheet copper for ornate items, I ended up going to a roofing manufacturer for prices on the things but they were way too much for my pocketbook... Welcome back by the way!...email me will you, I've lost your addy.

granpaw

Steve, years back I did quite a bit of work with copper sheet and flashing, with thicknesses as large of 0.125" for large heatsinks. This was around 30 years ago, and for the most part we used 50/50 tin/lead solder, and fluxed the work with a liquid acid flux sold under the name of "Tinner's Fluid". I'm not sure that this is still sold, but then it was a liquid acid flux available at every hardware and plumbing supply store. The combination produced very strong and durable joints, but required that all traces of the flux be removed after completion of the joints.

The downside was that visible solder, while bright at the outset, tended to darken through oxidation over the passage of years.

Were I doing it today and if long term appearance was an issue, I'd use one of those new silver based solders using for plumbing, along with a suitable flux. The other alternative would be a silver solder and a Mapp Gas flame, or an oxy/acety torch. This will give you a joint that is arguably stronger than the copper itself, but perfection of such joints requires considerably more practice than simple soft solders.

Brazing is another technique that you may want to consider. Like a hard solder (silver solder for instance), you'll need a specialized flux and a high temperature torch. Your application does not sound as though you would need to resort to such an extreme (a fountain), so I would start with a conventional soft solder and flux, then proceed to more extreme techniques only as the needs of the application demanded.

Hope this helps.

Harry C.

Steve B wrote:

You might want to ask over at sejw. Solders real easy. Typical plumbing flux is zinc chloride. proly wouldn't want to use any acid fluxes.

You could also consider not soldering, but doing something like what Idid in a closet: Plywood walls, 1/8 x 1" strip over the seams. Looked really cool--well, at least in my closet! This is for larger areas tho. Soldering edges, corners, etc. sort of leaves you no choice. May consider silver solder. Or even brazing! Or epoxy. :) :)

But here's the bigger problem w/ copper, as a decoration. Yeah, it's beautiful, but to *keep* it beautiful is constant maintenance--unless you just want the patina, but then, as a roofer pointed out to me, you gotta really like *green*!! The solution is to coat it, somehow, but that always struck me as cheating, and ultimately temporary/vulnerable.

An alternate solution is to use bronze sheet. Will knock yer socks off, it ages *really really nice*, w/o patina, fwiu. Different shades of bronze, as well, altho I don't know if you will have many options when buying sheets. Not sure of the available gauges, either, below 1/8. In machining parts for my Folly, I use brass only for practice, bronze for the real parts. Big diff.

Keep in mind there are all types of copper as well, roofing copper being the cheapest and softest. But you can buy all grades/hardnesses in sheets.

It can b e TIG welded. Randy

Hmmmmmmmmmmmm. A TIG is on my Christmas list. I'll have to wait. I have done a lot of SS TIG, and am 6g TIG certified. But, I never really thought of it. How do you think it would do on a 90 corner where the edges are just folded up and you have to fusion weld the corners? On a lap, it would probably be better, and I imagine one could turn down the voltage to control the heat.

I have never TIGged copper. Does it have hot shortness as aluminum does?

Mainly, some of this copper is going to be used to hold water in fountains, and it needs to HOLD WATER. I think I could solder, or even epoxy it, but TIGging sounds like a very plausible alternative.

Thanks. Please post answers.

Steve

I'm not a welder but I have to pretend to be once in awhile. I'm not sure what all the terms mean.

If by hot shortness you mean that heat is pulled away then yeah. I welded up a short length of "hex tube" by milling 60 degree edges on

1/8" sheet (I think it was) clamping to a form, and just fused the seams. I think I had to start the run hot then back off some once it started to flow. I don't know how thin of sheet you can get away with welding though. Just practice. HTH Randy

"Randy Replogle" wrote

Hot shortness happens when a metal is heated to it's melting point, and has a tendency to collapse under it's own weight leaving just a hole. Aluminum is notorious for that. I guess I'm asking do you get a lot of instances of burnthrough when doing copper?

Steve

I've only welded it a couple of times and it's been awhile, but I think maybe so because I remember having to keep the torch moving fairly quickly. Sorry I can't be much more help. I haven't seen anything from Ernie Leimkuhler here for awhile but he's probably got good answers. You could Google the group archives. He may have given me ideas once upon a time. Randy

Greetings Steve, Regular lead free plumbing solder and paste flux will work great. Do abrade the copper before soldering to remove oxides. If you have a joint where one sheet laps another by 1/2" or so then tinning before soldering is best. You can buy flux with solder granules in it for tinning and soldering. The silver bearing plumbing solder is pretty strong but even stronger is a product called "Super Sil-Flo" that's sold at hardware stores. It's sold by Forney. It has no silicon in it. There's another similar product called "Sil-Phos" that is similar and may contain silicon. Anyway, these are brazing alloys suitable for copper and copper alloys and is self fluxing on copper. So clean joints result. The color is close to copper too. You do have to get the copper about twice as hot as with plumbing solder though. Another nice feature of the stuff is that you can use it to build up areas, like fillets. After soldering the copper if you clean it well, and I mean the whole sheet or piece, it will patinate the same. Cheers, Eric

If there is any chance of someone drinking water contained in one of these creations, then you should use lead-free solder. "95-5" is sold at hardware stores for water pipes. It works about as well as 60-40 tin-lead solder, but is quite a bit stronger. You generally use a paste solder for things like this, and there is no flux in the solder. There are paste fluxes and Zinc Chloride liquid fluxes. You may want to experiment with both to see what works best with your torch technique.

The HAZ is not going to be all that different once you clean the whole piece. The solder will not take the same patina, of course. If you have to make visible seams that must blend, then something like TIG might be the way to do it, although TIG'ing copper takes a lot of heat. If the seams can be hidden, then don't worry about a HAZ, just clean all flux residue off.

Jon

Yes. I've only done a few pieces, and they were mostly 1/8" and thicker. I did see that the entire piece pretty much heated up to the same temperature before I started to get any fusion. So, once you get it hot and started to weld, you had to take it very easy on current and keep the arc moving. You definitely couldn't build up a big puddle and then drag it along like on steel.

This "hot short" business seems to be a misnomer to me. I think the problem with both these metals is that the heat conductivity is so high that you cannot get one hot spot with all the surrounding material significantly cooler.

Well, solder is a good choice, you have no chance of the whole thing melting down into a puddle. There is also phosphor-bronze brazing rod that is made for air conditioning and such work, and has a much lower melting point than pure copper. It is still high enough that you can melt the copper if your torch flame gets a bit out of your control. But, you have a temperature reading by color of the glowing metal, so once you know the color you need to heat to, you can control it quite well. Generally, no flux is needed with this braze. You can't do this with the standard propane-air torch. At least MAPP-air, or Acetylene-air as the plumbers use, or oxy-acetylene. Some of these phosphor-bronze brazes can be close in color to the copper, but that doesn't mean the patina will blend in.

TIG should also make a very reliable joint. The very first piece I did came out very well. If you have ever successfully TIG'ed aluminum, copper should be no trouble. I've made a few barely passable test welds in auminum, so maybe the copper was even easier.

Jon

If you can use a piece of steel as a backup, the problem should be totally eliminated.

Jon

Check out Blockade by Harris

This is a low-temperature brazing material specifically intended for joining copper. It's much stronger than solder, flows well, and you'll get a fairly decent color match. This stuff runs at lower temperature than the usual phos and sil-phos stuff used, and it can cope with fitup not as good as the other materials require.

You might be able to get a free sample. That's how I know about it

-- the guy at the welding store handed me a couple of sticks of it and said, "try this, Don, I think you'll like it!" (He was right.)

Interesting stuff Don, You have any idea of it's strength? I do 1/8 scale locomotive boilers outta copper, 6 to 8 inch Dia... Been using Uniweld 1000 PhosCopper for years... if this is strong enough it woudl make things a bit eayser..

---.- Dave

I weld a lot of 0.043 inch copper. I use DC TIG with deoxidized copper rod. If you are already a skilled TIG welder you should not have a big problem.

Note that the current requirements are high, on the order of 1.5 or 2 amps per 0.001 inch. I set my TIG at 90 amps to weld 0.043 inch thick copper.

Copper presents many of the same welding challenges as aluminum, fairly easy to burn through, highly conductive of heat. However, copper is less likely to crack, in my experience. I tend to think of them as similar in terms of the challenge of welding them.

Phos-copper rod is often used to braze copper for fountains, no flux needed, but you will need oxy-acetylene (or oxy-propane or oxy-MAAP) to braze it. Phos-copper rod works slick, the color match is not bad unless you grind it to bare metal. Much easier to get watertight joints with phos-copper than TIG welding. Fast, lower skill process.

With TIG welding, the color match is very good, but not undetectable. I don't do a lot of patina work, so can't comment on how the weld takes patina vs the base metal.

Richard

Steve B wrote:

Just going off on a copper tangent here. I recently built a glass block window and used copper flashing around the edges. I sealed it up with clear silicone caulk, and noticed that the caulk made it turn green right away--instant patina. The green isn't a problem, but I'm curious why the silicone caused this reaction. Is there an alternative product that won't have this effect?

Probably not the silicone. Most like;y the acetic acid the the caulk.

Chuck P.

On Mon, 20 Nov 2006 16:17:25 -0600, with neither quill nor qualm, Jedd Haas quickly quoth:

Most silicone caulks give off acetic acid while curing. Plain acrylic caulk wouldn't have done that.

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Most older generation RTV silicones evolve acetic acid during cure. GE-II silicones evolve methanol. I would presume you used a 1st-generation silicone, and the 'patina' is actually copper acetate. It's very soluble in water and hygroscopic -- so it's going to attract water during humid times, and might even continue to corrode for a while before all the acetic acid has consumed as much copper as it can.

LLoyd