How to patina copper?

Submitted by G-man on 1/16/05 at 3:43 PM. ( ) 199.224.119.243

I did a copper sculpture for a fish base and want to patina the copper to get the green look,verdegris I think its called.I tried muriatic acid and it did nothing (20%) Do I need hydrochloric or sulfuric? (I know muriatic is diluted hydrochloric hence the 20%)or is there something else?Thanks for any suggestions.

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Here ya go

This response submitted by cur on 1/16/05 at 7:04 PM. ( ) 4.227.11.159

Antique Green:

One ounce Copper Nitrate
One ounce Calcium Carbonate
One ounce Ammonia Chloride
One quart Distilled Water

Warm the copper base and the mixture to about 180F
Apply with a sponge by stippling
For color variation, place in boiling water after drying.

'At's what I use for deep green patina on copper.

You can apply with a brush to achieve a more uniform effect. You can also dilute the mixture with water to achieve pale greens and deepen by adding additional coats.

Muratic acid will clean it....LOL, as if you didn't already find that out. Use HCL in 1-20% solution to clean and etch all CU3 from the copper before applying patina. Rinse HCL off with distilled water and sponge it up.

Hope this helps.


Here ya go

This response submitted by cur on 1/16/05 at 7:07 PM. ( ) 4.227.11.159

Antique Green:

One ounce Copper Nitrate
One ounce Calcium Carbonate
One ounce Ammonia Chloride
One quart Distilled Water

Warm the copper base and the mixture to about 180F
Apply with a sponge by stippling
For color variation, place in boiling water after drying.

'At's what I use for deep green patina on copper.

You can apply with a brush to achieve a more uniform effect. You can also dilute the mixture with water to achieve pale greens and deepen by adding additional coats.

Muratic acid will clean it....LOL, as if you didn't already find that out. Use HCL in 10-20% solution to clean and etch all CU3 from the copper before applying patina. Rinse HCL off with distilled water and sponge it up.

Hope this helps.


Thanks cur

This response submitted by G-man on 1/16/05 at 7:20 PM. ( ) 199.224.119.243

The plethora of knowlege that can be found here will never cease to amaze me.


That is because

This response submitted by cur on 1/16/05 at 7:26 PM. ( ) 4.252.241.242

Many of us have done so much, with so little, for so long, that we can now do everything with nothing..........Glad I could help.


Faster patina

This response submitted by Alex on 1/16/05 at 8:24 PM. ( ) 66.32.151.235

Just pee on it and leave outside 24 hrs, presto!


Urec Acid

This response submitted by cur on 1/16/05 at 10:41 PM. ( ) 4.252.241.242

Alex, that may have been a left-handed joke, but uric acid is used to impart patinas on bronze, copper and brass. Of course cow urine is used for the purpose, and the break-down (ammonia cycle) seals and purifies the stain. The problem with that is the patina imparted by soaking bronze in vats filled with cow urine and sawdust is a rich brown, and not the green the poster requested........

Of course, you are confusing peeing on a Dumpster at midnight with true patinas. If you had been sober during the exercise, you would have noticed the dumpster was already painted GREEN!


One more option ...

This response submitted by Kevin on 1/17/05 at 8:52 AM. ( ) 24.116.178.139

is to use plain white vinegar and salt. I'm not an expert on chemical reactions, but this method worked for me.

http://www.kcdesignstaxidermy.com/o-cp-2.jpg

I disolved as much salt as I could in a cup of vinegar.
Put it in a small spray bottle.
Misted it onto the copper sheets.
Let it sit over night.
Presto, the above picture is the result.

Good luck,
Kevin


Salt and vinegar

This response submitted by cur on 1/17/05 at 1:33 PM. ( ) 4.226.228.105

I checked the photo and that green is not the patina that was requested. Basically vinegar (acetic acid) and salt combine to make a cleaning solution for copper. The surface rapidly oxidizes following the initial stage, and the color you have achieved is mostly carbonate and sulphate. If you did not clean the surface after the oxide build up, the corrosion will likely continue.

Salt, or sodium chloride, combines with acetic acid from the vinegar to produce sodium acetate and hydrogen chloride. Hydrogen chloride is a strong acid and the combination of it and sodium acetate rapidly cleans the surface. The cleaning process leaves a very pure metal surface which quickly corrodes when exposed to the water, oxygen, and carbon dioxide from the air. The finish achieved with the vinegar and salt is just rapid corrosion.

Vinegar is dilute acetic acid, around 7% in solution. You can buy acetic acid from photo shops in 28% solution which will do a much better job than vinegar.



Cur ...

This response submitted by Kevin on 1/17/05 at 4:43 PM. ( ) 24.116.178.139

you never cease to amaze me. Most of the time when I read your posts, I think, "how could one person have all of this stuff in their head ... and still be sane?"
When I built that pedestal, I wanted something a little different. I love the way copper looks with any kind of patina. Originally, I thought you could only get it to come out green. After a little research, I found out (that with different chemicals) you can get a rainbow of results. When I read the chemical ingredients to achieve the different colors, I wasn't even sure it was in English. Hell, I'm still not sure! I finally found the "quick and easy - poor man's recipe" of vinegar and salt. Like you said, it isn't the antique green, but it was quick, easy, and I found all of the ingredients in my pantry. I didn't know that it wasn't really a patina, I just saw green, and that's what I needed.

None the less, my hat's off to you, wise one.
I hope that one day I know half of the stuff that you've already forgotten.


Kevin


Who

This response submitted by Alex on 1/17/05 at 4:52 PM. ( ) 66.32.151.235

Says he is sane ? LOL

It was not Joke Pee have being used in copper for centuries to obtained a quick patina, I just missed on the original wanting it to be green. Ha ha


what next?

This response submitted by Dev on 1/21/05 at 2:00 PM. ( ) 69.27.245.250

I know nothing. After you achive the patina you want, what kind of finish can you apply to copper?
Thanks


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