Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing 1989-2024
-----
Copper patina problems
Tip: Readers can learn from your situation
but not from an abstract question, so
most readers just skip past them.
Q. How are the durable green/ blue copper finishes on statues produced & maintained? Is a torch used? Are they clearcoated?
Lisa Bengston- Victoria BC, Canada
November 18, 2023
A. Hi Lisa.
You'd probably have to name a stature and provide a pic for a more definitive answer, but buildings, roofs, and statues with blue/green verdigris patinas are probably just old and natural. Certainly artwork might be waxed or clear coated. Flame coloring is primarily interference coloring from burnt oil to my understanding and would not be expected to be durable, nor to retain good coloration under a wax or clearcoat.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
⇩ Related postings, oldest first ⇩
Patina is very dark, blackish, instead of green
Q. I am putting a green patina finish on copper tubing. My question is when I apply the solution should the copper turn very dark? The copper was cleaned with #0000 steel wool
⇦ this on
eBay or
Amazon [affil links] and washed with muriatic acid
⇦ this on
eBay or
Amazon [affil links] , then rinsed off. The copper was still a bit wet when I started to apply the solution. I used a commercial patina which did produce the green patina. Unsure about very dark copper, Is this normal?
Thanks
- Chambersburg Pennsylvania
2000
A. Jeff, it is likely your tubing is alloy C12200 which contains phosphorus. When applying muriatic (hydrochloric) acid, you would get a smut (coating) formed. I am guessing your patina process, like most, uses mixed, mildly acidic chlorides, or oxides that react with the copper surface, and develop a green color when dry. Perhaps a smut prevents the patina reaction by inhibiting the surface. I would try a dip in 10% nitric acid, to get a bright copper surface, (like a new US penny), rinse with deionized water, then apply the patination solution. Do not allow surface to dry off between steps. If this fails, you may need to use copper tubing that is unalloyed, such as C10200.
W. Carl Erickson- Rome, New York
Q. I would like to know what chemicals I could use to put a green patina on new copper.
Thanks,
- Sandy, Utah
2002
A. 50% vinegar ⇦in bulk on eBay or Amazon [affil links] . I put my copper pipes (from the hardware store) that have been cleaned with steel wool, in a five gallon bucket and spray, spray, spray. I turn the pipes about half way thru the process. I also use copper wire and caps on my garden sculptures so they are also in the bucket. I let them dry between spraying. I can get a beautiful patina overnight! I finish with a rub of linseed oil to preserve the patina. Beautiful results!
Product designer - Pinon Hills, California, USA
----
Ed. note: Thanks for the idea and the pictures, Teri!
Q. I used a solution to add a patina to my copper table. It came out TOO green. Any solution I can use to take some away?
Susan Herrgesellhobbyist - Cottonwood, California, USA
October 31, 2011
A. Remove the patina using a weak solution of sulfuric acid (10 %) and re use your patina solution more diluted . Or try to put on some wax on your patina. The wax will darken the patina .
Pieter Vanden DaeleSculptor of bronzes - Oudenaarde, Flanders, Belgium
November 1, 2011
Q. I trust these tips will apply to my bathroom copper sinks? I especially like the Miracle Grow and water idea. I was told not to put any cleanser or cleaners on the finish, so I only rinse and dry the sinks. They look like earth - lovely in their own way - but spotted brown and dull.
Linda Prejean- San Diego, California, USA
January 8, 2012
A. Hello Linda,
It is probably possible to create a smooth, consistent color and clear coat it for durability. But if you are letting bare copper be exposed to the conditions of a bathroom sink, spots and dullness must be expected. You need to choose, not expect bare copper not to spot :-)
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I have a nice old weather vane that has a natural black patina on the copper. I am toying with the idea of trying to change the patina to green. Can this be done and if so how?
Don Geuea- North Pole, Alaska, USA
March 13, 2012
Q. I am attempting to create a patina finish (light blue green), on a piece of copper to be the flow-surface of a large standing fountain (lots of running water!) Can you advise as to how to safely produce a finish which will stand up to a gentle flow of water with hopes of a durable result?
All the best
- New York, New York, USA
December 28, 2012
A. Hi Mike. I don't think it can be done without clearcoating. The blue-green coloration is quite soluble and non wear resistant. Pennies resting quietly between boardwalk slats are blue-green, whereas pennies in circulation always turn brown, not green-blue, because the blue-green has no wear resistance.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Thanks Ted,
Q. Can you advise about what types of coating are suitable for application to patina/copper? I am dreaming in hues of blue/green. Again it is for a fountain flow surface!
All the best.
Michael
- New York, New York, USA
A. Hi Mike. There are excellent books about patinas, such as "The Colouring, Bronzing & Patination of Metals" [on eBay, Amazon, AbeBooks affil links] . But if you are not an artist, buying a commercial patinating solution such as Jax or Modern Options sounds more promising. I'd try spraying a two-component automotive clearcoat on after the patinating because, as I say, those blue green tones are highly soluble salts (you've probably seen the staining of concrete below most copper, brass, and bronze outdoor items).
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hi, I recently purchased 2 large 30" copper seamless lip water bowls, that sit atop our swimming pool wall. Water (salt) fills and flows into the swimming area. New, they were as shiny as a spankin' new penny, but the exterior has since turned a very unattractive dark brown. The interior has formed a desirable blue/green patina, but only at the water line.
I have read previous suggestions, but am looking for help regarding application process, specifically "trapping" the spray. Any ideas for such a large item? Thanks, Rick
- Folsom, California USA
June 24, 2014
Q, A, or Comment on THIS thread -or- Start a NEW Thread