What darkens copper?

[ARCHIVED THREAD] - What darkens copper?

Posted: 4/8/2006 6:11:22 PM EDT

I need to antique some copper but everything I've found is Expensive and has a hazardous shipping charge. There has to be something I can get locally.

Posted: 4/8/2006 6:11:49 PM EDT

[#1]

Some acid.

Posted: 4/8/2006 6:12:14 PM EDT

[#2]

Posted: 4/8/2006 6:14:05 PM EDT

[#3]

A natural hot spring. Seriously, some sulfur.

Posted: 4/8/2006 6:16:10 PM EDT

[#4]

Quoted:
A natural hot spring. Seriously, some sulfur.

Sulfur and hot water?

Posted: 4/8/2006 6:16:13 PM EDT

[#5]

Time

Posted: 4/8/2006 6:19:37 PM EDT

[#6]

Quoted:
I need to antique some copper but everything I've found is Expensive and has a hazardous shipping charge. There has to be something I can get locally.

What do you mean by antique and darken? Darkening is caused by oxidation ie by oxygen. Antiquing (sp?) can be done with acids and will turn some of it green.

Posted: 4/8/2006 6:23:29 PM EDT

[#7]

Quoted:
Quoted:
A natural hot spring. Seriously, some sulfur.

Sulfur and hot water?

I was in New Zealand once in a natural hot spring. I had some pennies in my swim suit pocket. After about an hour, the pennies were black.

Posted: 4/8/2006 6:25:42 PM EDT

[#8]

Try eggs.
Eggs are high sulfur.

Posted: 4/8/2006 6:28:48 PM EDT

[#9]

Quoted:
Quoted:
I need to antique some copper but everything I've found is Expensive and has a hazardous shipping charge. There has to be something I can get locally.

What do you mean by antique and darken? Darkening is caused by oxidation ie by oxygen. Antiquing (sp?) can be done with acids and will turn some of it green.

Like this

Posted: 4/8/2006 6:30:51 PM EDT

[#10]

which acids oxidize copper?

my only experiences with acids and copper ended up with REALLY SHINY pennies.

Posted: 4/8/2006 6:35:28 PM EDT

[#11]

Quoted:
which acids oxidize copper?

my only experiences with acids and copper ended up with REALLY SHINY pennies.

maybe diluted sulfuric acid?

Posted: 4/8/2006 6:36:44 PM EDT

[#12]

Piss on it.

Or does that turn it green?

Posted: 4/8/2006 6:39:05 PM EDT

[#13]

Quoted:
Piss on it.

Or does that turn it green?

Maybe later but probably yellow at first

Posted: 4/8/2006 6:42:12 PM EDT

[#14]

I've done a lot of work with copper. To make it black, the best thing to do is to heat it with a propane torch to a certain heat. That will turn it black-grey. HOWEVER, if you don't heat it enough it will only slightly darken, and if you heat it too much the black will flake off exposing an odd combo of pastel pink and orange and darker purples.

Also, it WILL soften it to a high degree. Discs of copper that I couldn't bend with pliers, after heating to the black/grey, can sometimes be bent with my bare hands.

Posted: 4/8/2006 6:52:04 PM EDT

[#15]

Quoted:
I've done a lot of work with copper. To make it black, the best thing to do is to heat it with a propane torch to a certain heat. That will turn it black-grey. HOWEVER, if you don't heat it enough it will only slightly darken, and if you heat it too much the black will flake off exposing an odd combo of pastel pink and orange and darker purples.

Also, it WILL soften it to a high degree. Discs of copper that I couldn't bend with pliers, after heating to the black/grey, can sometimes be bent with my bare hands.

That could be an option

Posted: 4/8/2006 7:23:09 PM EDT

[#16]

Radio Shack sells a 16 oz. bottle of Ferric Chloride solution, that is intended for use in etching bare copper-plated printed circuit boards. When a piece of clean, bare copper is immersed in this solution, it gradually turns dark, over a period of about half an hour. This process is hastened if the solution is warm and/or continuously stirred.

Normally, you leave the copper in the solution until all unmasked areas are completely etched away. However, if you remove it sooner, you get a dark patina. Wash it gently in running water, let it dry, and then spray it with a protective coating of clear polyurethane, Krylon, etc.

Posted: 4/8/2006 7:26:40 PM EDT

[#17]

www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Product&ID=60864

Blacken-it is used by model railroaders to blacken copper and brass.

Doesn't ol' AFM know some stuff???

Posted: 4/8/2006 7:39:09 PM EDT

[#18]

This may sound kinda crazy, but I sometimes work with copper alloys. (machinist) I've noticed that if you leave Tap Magic tapping fluid on copper, it'll tarnish after a few days. It seems to happen faster when the Tap Magic is put on freshly exposed copper surfaces. IE Use some super fine Scotch Brite or steel wool to buff up finish. If you want copper to look like silver, a company called Hesse makes Cyanide Silver Plating solution that'll change it's whole appearance. We use the cyanide silver plating solution to keep the copper from corroding (green) when exposed to water.
Another method is to heat the copper with a torch (rosebud) until it starts to glow and let it cool on it's own at room temp. That'll speed up the oxidation process a great deal.

Posted: 4/8/2006 7:48:10 PM EDT

[#19]

Well, you can heat it with a blowtorch and drop it into some water...

If you get the temperature wrong, it will turn red or dark black.

Posted: 4/8/2006 8:20:12 PM EDT

[#20]

I don't know how much you need, but coin collectors use this stuff. Deller's Darkener It sells for five bucks for a quarter ounce.

Posted: 4/8/2006 8:57:36 PM EDT

[#21]

When I was in high school, one senior art class project was to do a copper picture.

You pressed the copper sheet out from the back to give a 3-dimensional effect.
To antique it, you'd apply a coating of Liver of Sulfur. This turns it absolutely black.

You'd then use steel wool to rub it off the high spots to give it more depth.

You can still buy Liver of Sulfur at many art supply houses.
Here's alink to some info on using it:
www.ganoksin.com/borisat/nenam/liver_of_sulfur.htm

Posted: 4/8/2006 9:32:14 PM EDT

[#22]

Muritic acid to strip all coatings, off, add a small amount of copper sulfate, brushed on. Without more info I think you are looking for the dull copper/ green patena.
Remember google.

Posted: 4/9/2006 7:13:20 AM EDT

[#23]

Thanks for all the ideas now off to work

Posted: 4/9/2006 7:26:22 AM EDT

[#24]

Everyone is talking about blackening it with heat. It's the oxygen that is doing it to a large extent. When you braze copper pipe and run nitrogen (ie 0% Oxygen) inside the pipe, it will remain absolutely the same as when you started. We do this when running copper pipe for medical gases in hospitals. If you want it dark dark brown place the object in a bag and fill with O2. If you want it black, I don't know.

[ARCHIVED THREAD] - What darkens copper?

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