How Can I Achieve an Aged Copper Look Without Chemicals?

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Discussion Overview

The discussion revolves around methods to achieve an aged copper appearance without using chemical solutions. Participants explore various techniques, including heating, exposure to air, and alternative substances, while expressing concerns about achieving an even finish and the specific color desired.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Experimental/applied

Main Points Raised

  • One participant suggests baking copper items in an oven and questions the appropriate temperature and moisture levels for achieving a brown color similar to old pennies.
  • Another participant mentions the possibility of using oxygen in a sealed environment to speed up the oxidation process.
  • Some participants discuss the effects of heating copper, noting that flame exposure creates an oxide coating that changes color based on thickness.
  • There are suggestions to experiment with ammonia and vinegar, although some participants express concern that these may lead to unwanted green or blue patinas rather than the desired brown.
  • One participant shares their experience of baking copper at 400°F, which resulted in a yellow color, and suggests that higher temperatures might be necessary.
  • Another participant proposes that the final brown color may be an acetate rather than an oxide and recommends boiling copper in vinegar or exposing it to acetic acid fumes.
  • Some participants report limited success with baking soda and express interest in trying Drano as a potential method.
  • There are humorous suggestions, such as using Coca-Cola, alongside serious recommendations to explore browning solutions available at local stores.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method to achieve the desired aged copper look. Multiple competing views and techniques are presented, with varying degrees of success reported.

Contextual Notes

Participants express uncertainty about the effectiveness of different methods and the specific conditions required for achieving an even appearance. There are also concerns regarding the potential for blotches and drip marks when using chemical solutions.

Who May Find This Useful

Individuals interested in decorative arts, metalworking, or DIY projects involving copper may find this discussion relevant.

NTL2009
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I'm working on some decorative items made of copper. I'd like to have them achieve the brown color of an old copper penny (or the old copper pipes in my home). I've read you can do this with some chemicals, but due to size/shape I'd like to do this some other way. I'm also concerned that any sort of chemical that I would apply would not give an even appearance.

I could bake these in an oven - will that help? What temperature? Would adding moisture help? Or does this just take months/years? I would wash them with detergent first to remove any oils, and scrub with an abrasive pad to expose an even, 'fresh' copper surface.
 
Engineering news on Phys.org
Google : ' patination solutions ' and ' patination treatments '
 
Yes, I have. Most are geared towards the green patina and chemical solutions. I just want the 'natural' brown of an old penny, and would like to avoid applying a chemical solution, due to size/shape and getting an even finish.

I might be able to get them in a (relatively) air tight compartment. Would flooding with oxygen speed things up (days?) I can get oxygen cylinders at a hardware store. $10 for 1.4 oz.

https://www.homedepot.com/p/Bernzomatic-1-4-oz-Oxygen-Gas-Cylinder-304179/202044702
 
NTL2009 said:
Yes, I have. Most are geared towards the green patina and chemical solutions. I just want the 'natural' brown of an old penny, and would like to avoid applying a chemical solution, due to size/shape and getting an even finish.

I might be able to get them in a (relatively) air tight compartment. Would flooding with oxygen speed things up (days?) I can get oxygen cylinders at a hardware store. $10 for 1.4 oz.

https://www.homedepot.com/p/Bernzomatic-1-4-oz-Oxygen-Gas-Cylinder-304179/202044702
If you heat copper in a flame, it immediately develops an oxide coating, which gradually gets thicker, and as it does so the colour changes. The colour seems to depend on the thickness of the coating relative to the wavelength of light, and also whether CuO or CuO2 are present perhaps.. Maybe you can try an experiment? Maybe very gentle heat over a few hours would work.
 
If course you must have come across this
https://www.wikihow.com/Darken-Copper

maybe try a bag that can be tied shut for a closed environment.
add some ammonia and put the piece in it hanging from a cord so that only the fumes act on the piece, and not the liquid

Experiment first with something not valuable.
 
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256bits said:
If course you must have come across this
https://www.wikihow.com/Darken-Copper

maybe try a bag that can be tied shut for a closed environment.
add some ammonia and put the piece in it hanging from a cord so that only the fumes act on the piece, and not the liquid

Experiment first with something not valuable.

Yes I did see that, but ammonia is for the green/blue patina, I'm looking for an old penny oxidized brown look. And yes, they also show various sulfur compounds for that, but I am concerned with getting an even appearance, and chemicals generally seem to leave blotches and drip marks. That's why I'm looking at options for exposure to air or heat.

I did try baking some scrap in the oven @ ~ 400F for ~ 1/2 hour. It turned kind of yellow.
 
NTL2009 said:
Yes I did see that, but ammonia is for the green/blue patina, I'm looking for an old penny oxidized brown look. And yes, they also show various sulfur compounds for that, but I am concerned with getting an even appearance, and chemicals generally seem to leave blotches and drip marks. That's why I'm looking at options for exposure to air or heat.

I did try baking some scrap in the oven @ ~ 400F for ~ 1/2 hour. It turned kind of yellow.
Heating in air should work, but I doubt 400F (200C) is hot enough. Try the cleaning cycle of an oven, which is closer to 1000F (~550C). Or alternately, throw it into a fire.
 
I believe the final brown colour is not an oxide but an acetate that develops later on the initial oxide layer. Try lightly oxidising the copper and then boiling the copper in vinegar or exposing it to acetic acid fumes.
Boiling iron in wine will protect it from rusting.
 
Baluncore said:
I believe the final brown colour is not an oxide but an acetate that develops later on the initial oxide layer. Try lightly oxidising the copper and then boiling the copper in vinegar or exposing it to acetic acid fumes.
Boiling iron in wine will protect it from rusting.

OK, thanks - I will try that later, and report back.
 
  • #10
https://www.wikihow.com/Darken-Copper
Simple and safe, summary of method 3.
Step 5. Turns copper a darker brown, roughly the color of an American penny. Mix concentrated hot baking soda. Step 6. Spray the copper with the solution. Step 7. Keep in a humid area for one to eight hours. This patina may take a few hours to develop, but keeping it in moist air will speed this process. Step 8. Depending on the environment and handling, the patina may wear off or fade before it sets permanently. If so reapply.
 
  • #11
leave it in coca-cola!

i am only kidding.
 
  • #12
NaOH I put a copper wire into Drano solution and it turned brown,
Baluncore said:
Simple and safe, summary of method 3.
The same wiki that I quoted.
Don't know where I messed up with ammonia, as that is for a green color .

Baking soda did not work for me, It seemed to make the lustre a bit of a shiny mat, with a very slight hint of pink, hardly noticeable.
 
  • #13
I did get a chance to experiment with the baking soda, and like @256bits , I didn't get much of a reaction.

Will also try the Drano later. Gonna be busy for the next few days. Will report back.
 
  • #14
go to your local gun store they sell browning solutions -also can be found at hobby lobby-! caution ! ammonia has a low odor threshold- also give pickle juice a try.
 

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