Letter 1198

Safely darken Copper, Brass or Bronze

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I am trying to figure out how I can darken metals of copper, brass or bronze in a relatively safe manner. I know that this can be done using selenious acid, but would like to find a way to do it with more "user friendly" chemicals, do you have any suggestions?

Thanks-
Paul

Paul D [name deleted for privacy]
- San Leandro, California

You can try Jim Watts' favorite sulfide from egg formula (see letter 1178 or 12714)

Tom Pullizzi Platronica.com Falls Township, PA

 

Selenium dioxide is a fantastic chemical for blackening copper and brass. In fact, it is the chemical trophy engravers use on a laminated brass plaque to make the lettering black (the lettering cuts through the lacquer). It's totally jet black and very hard. The product they use is called Gravoxide or oxidizer.

It's more readily available in Birchwood-Casey [link is to product info at Amazon] Gun Bluing. It's advertised as a blue/black oxide finish for steel but it is very effective on brass/copper. Brasso [link is to product info at Amazon] polish does not readily remove this finish.

I'd recommend an acid pickle to remove existing oxide or whatever method you have to get the metal very, very clean first.

Danny Miller
Austin, TX

Can anyone give me the location/phone number of where I can get in touch with the supplier Gessein^^Gesswein referenced in one of the responses above?

Kim M [name deleted for privacy]
- Azle, Texas Tarrant

The spelling is incorrect on your inquiry, it should be "Gesswein" polishing tools and accessories.

Gary Garcia
- Modesto, CA, USA

We are lasering brass with a YAG laser and then using Gravoxide to turn the lettering black. It looks fine for a few days but then gets fuzzy looking (spider webs out from the text) because the gravoxide isn't neutralized (maybe?) and keeps working. Does anyone have any ideas about another chemical to use or how to stop the Gravoxide from staying active?

Joe Midkiff
awards industry - Statesville, NC, USA

I am etching brass washers to make jewelry and would like to know of a relatively safe and economical way to do this. I have some directions that call for brass darkeners (Brass oxidizer) ...it comes in a pint size container...I don't need anywhere near this amount.

Kathryn Adams
Teacher - Easley, S.C., USA

Ed. note: Brass Darkening Solution [link is to product info at Rockler] is available in 2 oz. bottles as well as 8 oz. and 32 oz. You are wise to not buy far more than you need. Good luck.

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April 23, 2007

Can someone tell me a simple kitchen formula for turning copper or bronze to green? I have heard something like vinegar and ammonia plus a third ingredient, but have no idea of the proportions. I want to know because I want to stain my concrete floor. I used silver, gold and copper powder from Daniel Smith on wet concrete and got a beautiful green and black coloration, with a little brown. Now I am working with dry concrete and I want to try the copper powder again, and spray on a solution that will oxidize it. Then I will apply a clear concrete finish. Thank you.

Jane Seymour
Hobbyist/artist - Freeland, WA, USA

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May 12, 2007

Well, more of a bathroom formula than a kitchen formula for turning copper to green: urine. Conservators of old paintings often use this method to create verdigris for mixing paint.

Lee Boychuk
- Saanichton, British Columbia, Canada

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June 4, 2007

I have a house built in 1963 and all of the kitchen cabinets and drawers have hammered copper pulls that are no longer bright and shiny. I would love for them to be black, but I don't want to just spray paint them a flat black. Is there anything I can do to make them oxidized to a black finish? I hope that this makes sense because I have never had any experience with metals.

Thanks-

Lauren White
consumer - Toccoa, GA, USA

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Hi, Lauren. If they are real copper (check with a magnet first to make sure they're not steel), and there is no lacquer or clear coat on them, what you have read on this page should work. Good luck

Regards,

Ted Mooney, P.E.  finishing.com Brick, NJ

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July 7, 2007 My daughter is moving into a new house. Her fixtures all have the appearance of oil rubbed bronze. I have a lovely chandelier that is perfect for her dining room, except it has a shiny brass finish. Is there any way to paint or otherwise refinish it to give it a darker, duller look? Terry Foster crafty mom - Columbia, MO, USA Hi, Terry. If you know the chandelier to be real brass, you can try to remove the lacquer from it with Acetone [link is to product info at Rockler] or lacquer thinner [link is to product info at Amazon]. Then you can darken it as above. But easier and safer, if not as permanent, might be a Rub 'n Buff The Original Wax Metallic Finish [link is to product info at MisterArt]. Good luck. Regards, Ted Mooney, P.E.  finishing.com Brick, NJ December 10, 2007 I would like to antique or tarnish some copper wire to tone it down---it's just to bright and new looking. Could I use the same methods used for antiquing silver? Karrie Crotty hobbyist - Seattle, WA, USA

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April 18, 2008 -- appended here by editor in lieu of spawning a duplcative thread

I have a lovely chandelier that has a shiny brass finish. I would love to tone down that shininess. Actually I would love to find a way to refinish it with out taking it down and taking it apart? I know that is a lot to ask. But, that would really be a pain.

Is there a way to do this?

Thanks,

Laura

Laura Nygaard
hobbyist - Rancho Santa Margarita, CA, USA

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