putting a patina on a copper piece

[Farmall]

The daughter of a friend is working on a copper sculpture (her first) and wants to add a patina to it. She has tried heating it, but didn't like the results.  I have no experience in working with copper, so I thought I'd reach out to you and ask for any suggestions.  Thanks in advance.

 

[Woodz]

Good information here: http://www.sciencecompany.com/-W160.aspx

[Chinobi]

look up the sculpt-nouveau products, I had the opportunity to talk to a few guys who use their patinas over the weekend and they had nothing but good things to say about them.

 

are there specific colors or patterns that she is trying to achieve?  heat patinas on copper can be quite striking but do require some experimentation to control.  I think it was a member here who suggested preheating the piece in the oven to bring the whole thing up in temp but not to the point that it starts to oxidize on its own, then your torch will only need to bring it up a little farther to start seeing colors, rather than needing to wait a long time and then overheat one area and have the color run too far.

 

flip through the copper section, non-ferrous heat treating ('?do=embed' frameborder='0' data-embedContent>>), and I think the chemical versions have been discussed pretty well in alchemy too. 

[Farmall]

Thanks.  My understanding is she basically wants the patina as if it had been outside for a while already.  Nothing real complicated.

[Frosty]

Amazoon has a copies of, "The Colouring, Bronzing and Patination of Metals" by Richardson and Howe running in the mid $40s - the mid $50s

 

A lot depends on what color you want. You can get a nice age green like the Statue of Liberty by tenting the piece and letting it soak in ammonia vapor.

 

I've had some pretty spectacular if unrepeatable results by treating copper like Raku glaze. Bring it to an oxidizing temperature, dull red is in the ballpark and expose it to carbon based smoke. Newspaper, leaves, sawdust, string, moose turds, etc. The smoke "reduces" the oxidized surface of the hot copper bringing it in varying degrees towards new copper color. You can get a lot of really outrageous colors, Google Raku Glazed Pottery for examples of what a person MIGHT get.

 

I don't know if I was supposed to but when a piece got to something I liked I'd dunk it in water to stop the process.

 

Folk LOVED it at demos. I should've made a coining die to strike and patina medallions but my life is about things I should've done.

 

Frosty The Lucky.

[Chinobi]

you might also find this post useful, check out the 'rustic blue copper', i think its the same process frosty has in mind (not the raku one, there was another discussion of that process that came up as a sidebar in this thread '?do=embed' frameborder='0' data-embedContent>>), and its definitely one of the safer recipes compared to the others!

 

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as is customary, the price for information here is photos :) hope it turns out well! (and safely if she goes with some of the other chemical cocktails)

[RyanMark]

Here's an easy way.  Less dramatic than others but works.

 

1. Clean piece of all oil and dirt.

 

2.  Dissolve non-iodized salt in vinegar to saturation.

 

3.  Mist piece with spray bottle and let dry.

 

4.  Repeat

 

The green stuff that forms, verdigris, is easy to sluff off and not good to breathe or ingest.  She can clear coat it afterwards.

 

The salt/vinegar solution also works as a pickle to clean off fire scale.  She might want to do that first.  Works best if the solution is warm.  I have a dedicated crock pot for this.

[Nobody Special]

I've far less experience with copper patinas, but something I'd reccomend for any new type of finish;

 

Rather than experimenting with the finished work, try out some smaller test pieces first. This allows you see what'll happen with different processes, or slight variations on the same process. I've done it while playing with linseed oil/turp/beeswax mix ratios.

[ThomasPowers]

Traditionally you celebrated the finishing of a copper roof by buying the roofers a barrel of beer and having them apply the results to the roof to start the patina off---so another ammonia process....