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topic 1198

How to Darken Copper, Brass or Bronze



A discussion started in 1997 & continuing through 2017

(1997)

Q. 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 [last name deleted for privacy by Editor]
- San Leandro, California


(1997)

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

pooky
tom pullizi signature
Tom Pullizzi
Falls Township, Pennsylvania


(1997)

A. PAUL,

I HAVE RECENTLY DEVELOPED A VERY SIMPLE PIECE OF CHEMISTRY TO BLACKEN COPPER. JUST TAKE THE ZINC PURIFIER USED IN A CYANIDE ZINC PROCESS, AND MAKE IT UP A 1% - ROOM TEMPERATURE. THIS HAS REPLACED OUR EBONOL SYSTEM WHICH RUNS HOT.

ALSO, THERE ARE OXIDE CHEMISTRIES USED IN THE PRINTED CIRCUIT BOARD INDUSTRY FOR MULTILAYER BONDING. THESE WORK ALSO, BUT YOU NEED TO WIPE THE PARTS TO GET A SOMEWHAT "SHINY" LOOK. WITH THE PURIFIER SYSTEM, THERE IS NO NEED TO WIPE.

REGARDS,
RAY

RAY DELOREY
- Cambridge, Ontario


(1997)

A. Use liver of sulphur Liver of Sulphur [linked by editor to product info at Amazon]. It will turn copper or silver from brown to black . You can order it from Gessein^Gesswein. This is an excellent product and works great. Although it does smell like rotten eggs.

Ed Kassery


(1997)

A. 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 Gun Blue [linked by editor 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 [linked by editor 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, Texas


Liver of Sulphur

Liver of Sulphur

June 25, 2009

A. To darken brass, you must first strip any varnish on it.

Surprising, one of the most commonly available household chemical you can use to darken brass is Palmolive Dishwashing liquid. Look at the label and see if it contains sodium bisulphite and other sulphur derivatives. These are very similar to the chemicals in Liver of Sulphur.

Apply the dishwashing liquid with very little water to the bare brass and keep rubbing till you get the color you want. This will take only a few minutes. When you get the color you want, wash off the dish washing liquid.

Hong Lim
- Avondale, Arizona


July 3, 2009

Hi, Hong. My Palmolive Dishwashing Liquid does not list its contents at all except to say that it is phosphate-free and do not use with chlorine bleach.

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


January 25, 2010

thumbs up signPalmolive actually worked. Can't believe it. Few minutes and it looked like it aged months - and a nice brown. Thanks for the great tip!

Jeff Mucci
- Pittsburgh, Pennsylvania


February 9, 2010

Q. Regarding Hong Lim's suggestion to darken brass with Palmolive Dishwashing Liquid, what would I use first to strip the varnish from a brass chandelier?

ELLEN DRESSEL
- Grand Rapids, Michigan


February 15, 2010

A. Hi, Ellen. If the coating is brass lacquer, you can remove it with with Acetone [linked by editor to product info at Amazon] or lacquer thinner [linked by editor to product info at Amazon]. If it's a more durable coating, you can probably remove it with Aircraft Stripper [linked by editor to product info at Amazon]; it will not hurt metal, but is really noxious stuff absolutely demanding goggles [linked by editor to product info at Amazon], protective gloves [linked by editor to product info at Amazon], and truly excellent ventilation.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



(2001)

Q. 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 [last name deleted for privacy by Editor]
- Azle, Texas


(2004)

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

Gary Garcia
- Modesto, California



(2004)

Q. 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, North Carolina


(2007)

Q. 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, South Carolina

----
Ed. note: Brass Darkening Solution [linked by editor 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.


(2007)

Q. 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, Washington


(2007)

A. 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


June 16, 2010

A. For the person asking about a green finish:

Green Patina Formula:

2 parts white vinegar
1 1/2 parts non-detergent ammonia
1/2 part non-iodized salt

Application:
Clean fixture with Windex-type cleaner.

Premix patina solution in Windex-type spray bottle
Spray Windex cleaner on fixture to break surface tension, leaving it on when you apply patina solution.
Apply patina solution by spraying onto fixture, preferably in the early evening on a high humidity night.
Allow to set for 1 hour, then reapply solution observing where you missed applying on the first coat. If there seems to be oil that is repelling the patina solution, clean it off with the Windex cleaner.
Allow to sit overnight. In low humidity desert areas, use a plastic bag to create a tent over fixture (without making contact with it) to help keep the humidity high during curing. If there is low moisture in the air, the solution will dry out without creating the patina effect.
The result will be a bright green powdery patina. Do not rub off. In time (and re-applications) this finish will become permanent. The brightness will fade with time. To reduce green, cut back on the salt content. Color and effect is greatly affected by application ambient temperature and humidity.

Scott at Redstone Manor
- Keymar, Maryland, USA


(2007)

Q. 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, Georgia


A. 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, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



(2007)

Q. 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, Missouri


April 18, 2008

Q. 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, California


A. Hi, Terry; Hi, Laura

If you know the chandelier to be real brass, you can try to remove the lacquer from it with Acetone [linked by editor to product info at Amazon] or lacquer thinner [linked by editor 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 [linked by editor to product info at Amazon]. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


September 8, 2008

A. I would try to coat the surface of the chandelier with a dark glaze. The result would be a delicate finish, but a Chandelier doesn't get much handling and would look great for a long time to come. You could purchase some water based glaze and add extremely dark water based paint (found in craft stores) until it is the color you like and paint it on the brass with a small brush. This will make it look "antiqued". You can do several coats depending on how dark you want it to look. It will also tone down the shine.

I have also painted brass chandeliers white or off-white, or even a color! They look gorgeous! Just make sure you have cleaned it well and spray it with white paint.

Angela Burns
- Chester, New Jersey


June 20, 2009 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. We own several lamps and lights that are Brass Plated. Can you please tell me how to tarnish the plating so that it appears darker? Is there a simply product that can be purchased to accomplish this? If so, can you please tell me where to buy such product? Thanks!

Tim Edwards
home owner, hobbyist - Clarkston, Michigan


April 2017

Hi Tim. If something is 'brass plated' instead of real brass, and you want to patina or darken it rather than paint or wax rub it, all you can do is cross your fingers and hope. Often the brass plating is too thin, worn or porous for good results. Further, a lot of modern 'brass plating' is not brass at all, but nickel plating followed by a brass-toned translucent lacquer; so when you remove the lacquer to attempt the patination, the brass color is gone.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


September 3, 2009 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I am working on a "shadow box" for someone who is retiring from the Navy. The shadow box holds a flag and all of the member's medals. Inside the shadow box is a brass plate with all of the tours of duty. Unfortunately it is very hard to read the etching, is there any way to darken the plate so the etching is easier to read?

Shannon Van Meter
Buyer - Ridgecrest California


September 30, 2009

Q. I want to match a new panel I am making with a hammered copper sink already in the room. How can I get the new copper to darken and what kind of wax is best for the finish? I called one company and the process they use on the sinks is "secret".

Lois Campbell
hobbyist - Oswego, New York


August 17, 2010

Q. Hi there, I have a lot of jewelry brass backings and would like to turn them black, but use a safe product so it can be worn against the skin and clothing,
Thanks so much for your help.

Debbie Brown
jewelry maker - New Zealand

September 28, 2010

Q. Hello, I need to darken brass for my work (lamps), but I don't have easy access to the darken-it like products.
Even Palmolive washing liquid is not available here (Indonesia) and they never write the components on detergents.

I tried eggs with very little success and I am looking for some simple way to reach.
Please help me!

FX Hoffman
product designer - Bali, Indonesia



January 23, 2011

Q. Hello ,
Does a blackened brass with Rockler's Darkening solution hold up in a outside weather environment? Thanks!

Ike Sin
- newton, Pennsylvania USA

January 24, 2011

A. Hi, Ike

No, it will probably not hold up outdoors. But you can apply brass lacquer after the darkening, and then it should be okay.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

Brass Lacquer


January 29, 2011

Q. Thank you for the info! A follow up question, is there anything that will darken brass and survive outdoors? Thanks Ike

Ike Sin [returning]
- newton, Pennsylvania USA


 

A. I'm not sure that we understood each other, Ike. If you blacken it and then lacquer it, it will hold up outdoors for a couple or a few years. The lacquer is easily stripped and replaced.

There are dark "Lifetime Finishes", which you may have seen on door hardware. But these require very expensive PVD (physical vapor deposition) machines, and are applied by OEMs not by consumers.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



sidebar2 March 18, 2011

Q. I have a chandelier made of steel and tubular steel and painted in a pewter color (cold grey/blue tones) with a highly lacquered finish. I'd like to change the finish to bronze (warmer tones) and I have some professionals telling me that it cannot be done over the high lacquer. Do you have any suggestions? Would auto paint cover? It is a detailed fixture and cannot be sandblasted b/c of the wiring.

I appreciate any suggestions.

Lisa

Lisa Gold
homeowner - Orange, Connecticut


March 21, 2011

A. Hi, Lisa.

Simplest, easiest, cheapest would be the Wax Rub if it works, so I'd try that first. If not, you can try removing the lacquer with lacquer thinner. If that doesn't work you can remove it with the far more powerful Aircraft Stripper, but only outside with good ventilation, not in place. Then you can use one of the fancy paints like American Accents.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



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