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How to patina copper (darken it)

Q. How do I get a patina on a selected section of a copper circle?

For instance, I have a 10-inch copper circle on which I want a half section to be lacquered and the other half being oxidized with ammonia [on eBay or Amazon (adv.)] to get a patina.

When I tried to do this, the lacquered surface also gets a bit tarnished and goes slightly black.

I am unable to control the desired outcome.

I am using Pure Copper circles and Spray Lacquer.

Matthew Smith
- Leicester, Leicestershire
November 12, 2022

Seam Roller
on Amazon

(affil links)

A. Hi Matthew. Apparently the spray lacquer is not an effective maskant against ammonia. Liquid maskants and "plater's tape" are two better masking agents made for the purpose ... but maybe just try black electricians' tape before exposure to ammonia. Make sure you roll it down really good at the edges (maybe with a wallpaper seam roller).

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

A. Try silicone sealant.Hope it helps and good luck...

Goran Budija
- Cerovski vrh Croatia
March 2, 2023

Call us at Maskcoat for all of your masking needs. 1-888-218-7227
Thanks, Jeremy

Jim Baldwin
Mask Coat LLC
supporting advertiser
West Monroe, Louisiana
maskcoat banner
April 18, 2023

⇩ Related postings, oldest first ⇩

Q. Great web site. We are in Phoenix Arizona, and just installed some beautiful copper landscape lighting. Right now it is bright penny-copper new. A couple of the lamps have fingerprints from whoever packed them visible as a brown/charcoal color. I want to remove the fingerprints, then speed up a "green" patina finish, not the dull copper brown we get here in AZ. I'm from the East Coast and love the blue-green copper roof colors in Boston and Providence and would like to emulate them.

Will a weak vinegar [in bulk on eBay or Amazon (adv.)], 0.50 part non-iodized salt, and 1.5 parts of clear, detergent-free ammonia. Spray on the area you want to patina and reapply every 1-2 hours until you get the color you want. The patina will look powdery, leave it alone, it will eventually work in the copper and get to that more 'glazed' look. 72 hours or so from when you apply it you should have a better idea of what the final look is.

2. Brown patina.
You need to dissolve baking soda [in bulk on eBay or Amazon (adv.)] in boiling water until it won't dissolve any more. Spray on to the area to be patinated after the solution has cooled, and reapply every 2 hours or so. This one will reach more towards the color of an old penny.

Marc Banks
Blacksmith - Lenoir, North Carolina USA

Q. Hi:

I am new and just discovered this site when I went looking for copper patina info. I need to know if I need to clean the copper after handling it when playing or if I can put patina over the fingerprints and not worry! Is there a site everyone prefers to learn, or is this the hobby one of those that you just try different things and learn? <grin> I want to make tiles 4"-6" and wonder which backing would work the best to use under the soft copper 36 gauge or even if I need it. I know, lots of questions and this may be the wrong place so gently tell me to get lost...<grin>

Terrie Kaufman
Interior Designer - Vancouver Washington - USA
March 28, 2014

A. Terrie,
You do need to have your surface clean of fingerprints. If you don't you'll end up with an irregular patina, I usually use disposable nitrile or latex gloves when I'm doing patina or finishing work. Heavier gloves if I'm dealing with anything highly caustic/corrosive.
At 36 gauge you're dealing with something that is more akin to foil or leaf. I'd highly suggest some sort of backing, but it really depends upon where these tiles are going to be used and if they are going to experience any wear. Ceramic will probably be the goto for doing it though.
For learning more about patinas and processes associated with such I highly suggest a couple of afternoons at your local public library or university. There is a wealth of information on patinas and finishes, you just need to put the time in.

Marc Banks
Blacksmith - Lenoir, North Carolina USA

Q. To Marc Banks Blacksmith - Lenoir, North Carolina
How much baking soda in water would be adequate? I have a small 12" hammered copper accent table. Ratio? Thanks for your time!

Judy Vogeler
- Esmond, Illinois USA
March 22, 2017

Sodium Bicarbonate

A. Hi Judy. Marc's posting was from 3 years ago so I'm not sure how soon he'll see your followup question. But he's telling you that instead of measuring the baking soda, just keep adding it to the boiling water until no more will dissolve. For an estimate, Wikipedia suggests that that will be about 236 grams per liter, i.e., about 20% by weight.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

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