Andy1845c

I know this isn't an ideal place to ask this, but I know there are some folks here that might be able to give me some information.

I am fascenated with the metal copper. I have been saving scraps of copper wire for a while now, and what I would like to do is convert all the scraps into a block or lump of pure copper. Just as an art object/conversation peice.

I read somplace (can't find the link now) that pure copper does not cast well and is prone to cracking unless other metals are added to it.

I remember seeing on tv how pure copper for use in electrical wire is made using an electroplating process.

I found this website that shows an experiment with copper plating on a very small scale. THE CHEMISTRY OF COPPER PLATING

Does anyone see any issues or have any comments on doing this on a slightly larger scale? I probably have a couple pounds of copper I would like to make into one lump. Are there any other chemicals I could substitute?

I'll leave it at that for now. I do have some more questions about the process, but i'll first see if anyone can advise me.

Many thanks!
Andy

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dknguyen

Wouldn't copper plating oxidize really fast? Why would you plate anything with copper as the outer layer?

What would happen if you just tossed it all into a wood (or maybe another kind of slightly hotter) fire? Isn't that what they used to do?

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Krumlink

It would have to be 1984F or some 1000 degrees Celsius.

You could make a ton of money at a metal reclamation center.

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Andy1845c

I'm not sure. Thats why i'm looking for opinions. I figure the lump of copper will tarnish no matter what method I use to make it, but maybe I could polish and clear coat it or somthing.

I tried melting a small amount of wire with a cutting torch once. It didn't flow very well and ended up with alot of pocks and cracks in it.

I'm not sure exactly how early man made copper tools and such. I guess I'll google it. I know copper and tin are mixed to make bronze, and that I think is a bit easier to work with.

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Andy1845c

I think its feasable to melt copper in a wood fire, as early man did it. But I haven't tried it yet.

Yeah, I could scrap it, but wheres the adventure in that?:P

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dknguyen

Acrylic conformal coating?

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3v0

I would think if you check the web you will find info on building a home foundry for brass, bronze, and alu. A good place to start.

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BeeBop

Yes; you need a bellows to deliver lots of oxygen. My grandfather had an old forge, which ran on coal. You had to turn a crank to pump the air into the base of the flame.

3V0 is correct, there are some home foundries on the WWW. I can't remember where, but I have seen them.

Of course, bronze is better for what you want...

Andy1845c

I have seen alot on the web for casting other metals, but I am under the impression copper is very difficult to cast. Here is the artical I couldn't find earlier - Copper and Copper Alloys Casting Problems It describes using crushed graphite to cover the melt and adding calcium boride or lithium. I don't really want to create an alloy. I don't know if thats what this would do, or if all the other stuff will end up as slag on top of the melt.

I guess I need to find a metallurgy forum. I've been looking but can't find one yet.

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3v0

Look for a forum on home foundry work. The graphite is providing a barrier between the metal and the air. I think we used borax but maybe that was just for forge welding. Too long ago.

A home foundry for melting bronze is not difficult to make. Mostly a weed burner stuck into a ring of fire brick (tangent to the circle) with a graphite crucible to hold the metal. Slab of fire brick for the top. Forge bands of iron to reinforce and bond it all together with furnace cement. LOL actualy you can line a large tin can with high temp brick and use it for small pours.


Is there some good reason not to make an alloy ?

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quixotron

yeah mix it with aluminum!

HarveyH42

Search backyard forge, should get tons of hits. Instructiables has several for aluminum, using coffee cans, soup cans, charcoal, and a hairdryer (forced air). I've done lead/tin pewter for years, and occasionally get an itch to try higher temp metals.

monkeybiter

i've seen copper 'bails' for 'simulating' through hole plating, i reckon you could probably make these yourself by plating thin strands of solder. could be a fun and relatively easy experiment.

Glyph

I've actually electroplated copper and created items on the miligram to multi-pound scale.

While its relatively easy to create a thin coating of copper onto other metals, the difficulties lie in getting the coating to be of the properties you want. Normally copper comes out as a matte salmon coating. While good for protection this looks terrible.

Special chemical additives like benzotriazole are added to the copper plating solution to change the deposition process and give you a mirror finish on the plated copper.

Things get tricky when you want to actually create objects, like a lump. This process is called electroforming and suffers from the problem that metals plated in this way don't assume an easily predicatable shape. This is because when the current is applied some areas are going to get a higher current density than others, this causes those spots to plate faster. Unfortunately, this process tends to occur with a positive feedback, the high density area grows in such a way as to incur an even higher relative density which in turn makes it grow even faster. In the end, you get a massive chunky deposit with feathered edges and "trees" growing accross its surface (you'll know what i mean when you see it....).

Concentrations of copper and acid is also important. Most copper plating is done with sulfuric acid and copper sulfate. high sulfuric acid and low copper sulfate tends to produce more even deposits, but is slower to plate. Reverse that ratio and the opposite occurs.

Alkaline copper baths work better, but are composed of very highly toxic chemicals.

additives added to the bath deplete after prolonged usage so you need to maintain those concentrations precisely. too little additives and the copper comes out crappy, too much and it looks like an alien copper fungus is growing on your stuff.

The amount of current is also an issue. Voltage is not what you need to control, its current. Too much current on too small an object will induce treeing and feathering. Too little current and the additives might not work since they need to "stick" to the surface based on the surface voltage level.

Filtration is a requirement when making larger pieces. if a speck of insulating dust hits your surface the deposit will form a pit. If a speck of conductive dust hits your surface the positive feedback i mentioned earlier will create a tree.

And even if you get the shiny mirror finish on copper it will quickly tarnish in air.

All of that being said.... There is nothing quite like the feeling of lifting out a beautiful mirror shiny object that you knew a few hours ago was a dull sand-blasted hunk of metal.

Copper is the easiest of the metals to plate and even a beginner can do a decent job.

Anything more specific you want to ask?

Andy1845c

Glyph, thanks for the awsome reply!!

I'm not too concerned about the shape of my copper "lump" when its done. I want it to be interesting to look at. Not a perfect cube or anything.

How do I figure out the right sulfuric acid and copper sulfate mixture? Trial and error? Is this mixed with water? Will the acid mixture last a while, or does it depleate and have to be changed though the process?

Do you have any suggestions on what a hobbiest like me could use for a power supply? I was thinking of an automotive battery charger, but that wouldn't allow me to control the current very much.

How is the filtration done? Is it sorta like a pool filter that is just circulating the solution though a filter?

What time frame am I looking at to take a couple pounds of scrap wire and make a couple pound lump? A week? a mouth? Way longer?

Sorry to bombard you with questions. I'm just glad to see somone here knows about this!

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