green patina on copper

[Scott A. Roush]

Just wondering if other people would share recipes for green patinas on copper. I'm currently trying a sawdust bury method.. 1 part vinegar, 2 parts ammonia, lots of salt. Dampen the sawdust, clean the piece to a bright finish and bury it in the sawdust. So far I'm getting a bluish green crust that doesn't adhere to the copper and the finish itself is a beautiful yellowish, etched finish.. which is nice. But not green. This was after 8 hours or so in the sawdust.

 

Any ideas or hints???

 

I'd like to just order one of the commercially made patinas.. but the hazmat shipping gets me down.

[Steven Gillespie]

I had a mix, but I can't remember at the moment. But time is the best one. Send some voltage through the piece, it will help if you have enought salt and moisture.

 

Cold bluing darkens brass to a purplish color, copper doesn't seem to be effected by bluing though.

If I remember right, older ships have copper plating on the hulls, and must be maintain due to corrosion.

Edited January 5, 2013 by Steven Gillespie

[Troy Christianson]

Scott. The hard way is to expose the copper for about fifty years to the elements :)/> . Obviously that probably is not the method you desire. We use a commercial chemical to patinate copper at work but only on small projects. The stuff is expensive and semi-toxic. It must be done outside, which is where 99% of our work is. I can find out where we buy it from but as you said it is the hazmat fees that kill you. We have tried some of the solutions you have and they sorta work if applied to hot copper. Acetic acid also works but that is essentially what you are using. Sorty that my ramblings have not been more help. I'll pick the brains of some of our roofers and see what they know. Now I hafta go forge some shards.

 

p.s. just talked with a friend on facebook. She is a sculptor and does alot of bronze castings. She uses diluted sulphuric acid! Then neutralizes it with a soda solution

Edited January 5, 2013 by Troy Christianson

[Wild Rose]

A whole bunch of recipes for colors from white to dark brown

http://www.sciencecompany.com/Patina-Formulas-for-Brass-Bronze-and-Copper-W160.aspx

 

 

note: be careful when using ammonia - too long of an exposure can cause embrittlement with brass amd copper but brass more so...been tehr done that

[R. Yates]

Miracle Grow & water, sprayed on copper, will turn it a beautiful green patina overnight. Ammonia and Salt makes a really great blue patina on the copper. Try a buried patina - use either sawdust or non-clumping clay cat litter in a ziplock bag and dampen it with the ammonia, then add the salt. You have to use a lot of salt, about the same amount as the ammonia or even more. Make sure it is all well mixed and then bury your copper piece in the mixture. Let it sit for at least 3 days. The longer you leave it, the darker the blue color will be. 5 days makes a beautiful speckled midnight blue and black patina.

 

Or just look here for a vast amount if their recipes .

 

http://www.finishing.com/faqs/patina.html

 

Best Regards

 

Sam

[Scott A. Roush]

Thanks Sam... that bury method is what I'm doing. But I didn't realize how blue it would make it. My first attempt had too much salt in it.. which somebody told be would actually scrub it clean. And that is what it did! I'm trying it again right now with less salt.. but sounds like it will be blue!

 

Need to get Miracle Grow I guess!

[Orien M]

Based on the mentions of ammonia, phosphate, and salt above, I feel compelled to suggest that urine might work pretty well

 

(It certainly made a nice browning agent on steel...I only tried it once because I was uncomfortable explaining to people how I did it! I need to come up with a good, harmless sounding technical term for "buried in pee-soaked sawdust"... )

[R. Yates]

Based on the mentions of ammonia, phosphate, and salt above, I feel compelled to suggest that urine might work pretty well

 

(It certainly made a nice browning agent on steel...I only tried it once because I was uncomfortable explaining to people how I did it! I need to come up with a good, harmless sounding technical term for "buried in pee-soaked sawdust"... )

 

Yes it works , Hoe ever it stinks and makes most all metals Black /brown . and based on other liquids available i chose to work with many others that Urine .

 

Sam

 

good luck with the Patina glad to help .

[Orien M]

I appreciate the feedback...I like using natural, local materials whenever possible, but may be going a little too far with this one...

Edited January 7, 2013 by Orien M

[Christopher Price]

Ahh, the old Pisspatina.

[Scott A. Roush]

Well I haven't tried piss but I can tell you this: If you need to get the job done quickly... Miracle Grow and water.. and a little salt. I dipped it and placed it on a rack over my woodstove and voila! And it is way more resilient that I thought it would be... can't even rub it off with coarse cloth. But the resilience may have to do with all the ammonia/vinegar/salt treatments I was trying beforehand. The etched surface provides a safe refuge for the verdegris...

[jake cleland]

have you thought about using eggs? hard boil and finely chop enough eggs to fill a sealable plastic bag big enough to hold the piece, and seal it up for a couple of days...

 

the only other thing i can think of is i used to have an acid based soldering flux i used for stainless steel and nickel, which i accidentally spilled on a piece of copper - produced a very tough and hard bright green patina. the flux was about 40 years old though, and the writing had worn off the bottle, so no idea of the brand, but it might be something to think about

[Scott A. Roush]

Jake... Eggs should yield sulphur which will blacken copper... at least that is what my 'liver of sulphur' does.

 

Fluxes have acids and salts in them which should help with the process. I know that you can get rapid results with shiny copper roofing material with just salt water and vinegar... but I believe that the sun shining on that warm copper roof is the catalyst that really gets in going. I think that is why my Miracle Grow treatment is working so well.. I scrub it clean, dip it in the Miracle Grow with a little salt and place it over my woodstove. The heat causes rapid oxidation...

[Al Massey]

Try a few days in Nova Scotia salt air. This stuff could patinate stainless.

[Serge Panchenko]

Scott, pour some ammonia in a container with a lid, suspend the copper piece above the ammonia (not touching) and allow the fumes to work on it overnight. You get a very even, amazingly tough blue-green patina.

[Scott A. Roush]

Interesting Serge... I can see how that would give you a more even finish than the bury and 'dipping' methods. How resilient is that method though? One of the nice things about the bury formulas is that they etch as well as patinate.. so the patina gets protected by being under the surface of the blade if that makes sense.

[Serge Panchenko]

Scott, I tried to apply some highlights after applying a patina this way, and was surprised how difficult it was to remove ANY of the patina with a scotchbrite pad.

[Jason Brown]

I always seem to get a range of color from green to black on the pennies in my car's cup holder when I spill coffee or a soft drink on them and forget to clean it up. I'll have to do some experimenting and report the results.