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Thread: How to get the right bronze patina?

  1. #1
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    Default How to get the right bronze patina?

    Even if I had time to polish my bronze, I have convinced myself I like bronze patina. I have noticed that patina comes in several types. I like the dark brown and smooth or dark green and smooth patina, but I usually get the crusty, light green patina. What I wonder is whether there is a way to get your bronze to patina the way you want?

    I've read in old posts that bronze goes brown in freshwater and green in saltwater, that polishing/buffing might be necessary for a good patina, and that you might be able to get parts to patina with "horse piss". I don't have any horse piss readily available and I was wondering if anyone has any information on this? (Yes, I've heard of Wrights copper cleaner, but haven't found any yet.)

    I have my cranse iron off right now and of the 4 bronze turnbuckles, 2 are green and crusty, 1 is more in the dark green direction, and one is dark brown. The brown one was replaced when I got the boat 4-5 years ago and is a Wilcox Crittenden while the others are Merrimans. I wonder if the WC one is brown because it is a different brand/metal or because it already had the brown patina before it got installed.

    Any information would be appreciated.
    James

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    Back in the dark ages when I was a sculpture major in college, we didn't have any horses around so we used stuff similar to this.

    http://www.artchemicals.com/Sculpt-N...shes-C538.aspx

  3. #3
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    Yup, the art crowd has figured out how to produce a wide variety of colors on bronze using chemicals to develop the patina.

    Just be careful with those chemicals. Many of them are pretty nasty.

  4. #4
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    Excellent. I've gone from guessing to too much information. I'll do some research and try to let you know how it works out.
    James

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    Use ferric nitrate. Then wax.

    I was a sculpture major (MFA) too.
    I love the smell of fresh cut plywood in the morning.

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    Quote Originally Posted by Bruce Hooke View Post
    Yup, the art crowd has figured out how to produce a wide variety of colors on bronze using chemicals to develop the patina.
    Right.

    This is the bible: The Colouring, Bronzing and Patination of Metals (1991), by Richard Hughes & Michael Rowe.

    372 pages.
    Watson-Guptill
    ISBN-10: 0823007626
    ISBN-13: 978-0823007622

    Here's another slightly more specialized volume: Patinas for Silicon Bronze (1996), by Patrick V. Kipper.

    225 pages
    Path Publications
    ISBN-10: 0964726904
    ISBN-13: 978-0964726901

    Happy corrosion!
    You would not enjoy Nietzsche, sir. He is fundamentally unsound. P.G. Wodehouse (Carry On, Jeeves)

  7. #7
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    I have an artist friend who might have one of those books, funny I didn't think of that until now.

    Would beeswax work? I was thinking of using a beeswax furniture polish on the threads of my turnbuckles to keep them from seizing and I could just use it to cover the whole thing (beeswax furniture polish was the only beeswax product I could find, they thought I was nuts when I asked about lanolin).

    Is Ferric nitrate something that they are likely to have at an art supply store? Or is there another place to get it?

  8. #8
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    Quote Originally Posted by jimmy View Post
    I don't have any horse piss readily available and I was wondering if anyone has any information on this?
    Drink some beer. Pee in a bucket. Heat the bronze, 300 degrees will do. Drop the bronze in the bucket. Do this outside, stand up wind.

    Rinse, wax, polish.
    Hey! It's MY Hughniverse!

  9. #9
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    Quote Originally Posted by jimmy View Post
    Is Ferric nitrate something that they are likely to have at an art supply store? Or is there another place to get it?
    I don't know for certain but I'd bet not. My experience has been that most art supply stores focus mostly on drawing and painting and other similar art forms, and that to get sculpture supplies you usually need to go to separate, more specialized places. In terms of availability the key question is whether there is some other commercial use for it. If there is, it may well be available locally. If not it may be something you have to mail order.

    However, everything I just said is based on my general experience with obtaining sculpture supplies, not on any specific knowledge about Ferric nitrate.

  10. #10
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    Quote Originally Posted by Hughman View Post
    Drink some beer. Pee in a bucket. Heat the bronze, 300 degrees will do. Drop the bronze in the bucket. Do this outside, stand up wind.

    Rinse, wax, polish.
    I recall hearing about a famous Swedish sculptor who got the right patina on his bronze sculptures by encouraging his sons to pee on them, so this technique sounds very worth trying...

  11. #11
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    Well, that actually sounds easier than trying to track down ferric nitrate, but somehow I'm still a little hesitant. I'm imagining a future conversation. Someone asks "How did you get that nice patina on your bronze fittings?" I answer "Ummm ... It's a natural process."

    I've been cleaning the light green crusty stuff off my turnbuckles and underneath they have a darker green patina that doesn't look as bad. For now I think I will put them back on the way they are and experiment with spare bits of bronze when I get my boat back together.

  12. #12
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    Then again you could say you "dicked around until you found the right solution"
    "Travel is fatal to prejudice, bigotry and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome and charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime" Mark Twain... so... Carpe the living sh!t out of the Diem

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    And then of course Ian there's the whole other side to 'bronzing' in an Aussie context....................

    Gotta go, beach for the W.E.!

  14. #14
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    Actually, you have to understand that "Bronze" isn't a metal, it's a class of alloys. Silicon bronze is the alloy that gives that wonderful, dark green, or brownish green, smooth patina (a coating of oxides, to be specific). But there are many alloys marketed as bronze that oxidize much differently. Manganese bronze (a high strenth yellow brass, really) is a common marine alloy, and tends to oxidize rather splotchy with kind of a rusty look, in no small part due to it's noticeable iron content. Aluminum bronze, or aluminum nickel bronze has it's own look, kind of a darkish brown. Red brass and yellow brass are common in tubing used for hand rails, gallows frames, etc. and they go their own way, as well. So the patina, the natural one, that is, is a factor of the alloy more than anything else.

    Chuck

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    At least if you tell passengers how you got the nice patina you won't have to worry much about them getting fingerprints on your hardware.

  16. #16
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    Forget the bucket. Piss in the toilet. Put bronze in the bowl. Set house on fire to heat water and bronze simultaneously.

    First things first, after all.
    If I had a dollar for every girl who found me unattractive, eventually they would find me attractive.

  17. #17
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    Tony Horowitz, in his great book Confederates in the Attic, talks about Civil War reenactors and how the commitment to authenticity varies among the disparate groups. The really hardcore enthusiasts are often called "button pissers" due to their method of achieving the perfect patina on brass uniform buttons.

  18. #18
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    you could hang it in the cesspit for a time (works on copper to get "old" patina fast )a trick from my grandfather who did a lot of restorations.
    but better use a strong string or wire and rinse well !

  19. #19
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    Up here in fresh water bronze is usually just a blah brown color. I seem to remember someone using citric based cleaner to give it some verdi gres(sp). Has anyone else heard of this?

  20. #20
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    Quote Originally Posted by Bruce Hooke View Post
    I don't know for certain but I'd bet not. My experience has been that most art supply stores focus mostly on drawing and painting and other similar art forms, and that to get sculpture supplies you usually need to go to separate, more specialized places. In terms of availability the key question is whether there is some other commercial use for it. If there is, it may well be available locally. If not it may be something you have to mail order.

    However, everything I just said is based on my general experience with obtaining sculpture supplies, not on any specific knowledge about Ferric nitrate.
    Good art stores DO have these things. The ceramic art supply houses also carry many of the substances. Most people do not know where real art stores are and there are less and less al the time. Sorry to say. All patinas are some form of acid treatment and give different colored patinas.
    The sculptors wax is much different than bees wax.
    sculptors wax is not what you want.
    Patinas are a whole discussion and every artist develops their own little concocktion.
    You could just mix white vinagar with 50% water and speed up the oxidation process.
    I love the smell of fresh cut plywood in the morning.

  21. #21
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    If you sail in salt water just rinse the bronze off then rub it with an oily rag. That will get most of the bright green off and leave the darker green underneath.

  22. #22
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    OK, vinegar is something I have tried and it will remove any patina or corrosion leaving you with metal that is nice and clean. If you leave it too long it starts to go a redish colour, which I suspect is bad, but hopefully doesn't go too deep.

    I think for now I am going to try the cleaning the cleaning off the light green crusty stuff method.

  23. #23
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    The results will vary depending on lot of factors, a 40 year old weather vane manufacurer near here moved to another town, and much to their surprise the patina process did not work at the new facility because of the different water.
    TALLY HO
    Ken

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    A water diluted ferric chloride solution is used to etch copper based metals, and is available through radio shack as printed circuit board etching solution, or through digi-key. it is a strong reagent so use caution.....even diluted.
    Wakan Tanka Kici Un
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