How to Darken Copper, Brass or Bronze

adv.
Hello all..yes we have such a chemical patina which is sold in kit form to do just this. Please find our Copper Patina Rescue kit at www.barrysrestoreitall.com. We offer two sizes based on area. Quick and easy to use. Using a hairdryer will speed up the process to dark. Good luck

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

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

Q. I recently read a response by Ray Delorey regarding chemically blackening copper. Ray recommended a 1% room-temperature dip of "zinc purifier" that is used in a "cyanide zinc process" as a non-wipe system for this blackening process. I would appreciate help in locating a source(s) for this "zinc purifier".

Thanks much,

RON RITSCHER
- Springfield, Missouri, USA
2001

Q. From this site I've read that "Zinc Purifier" is an easy and safe way to turn copper to BLACK. I'm good with Google searches, but can't find a source anywhere that I could find to purchase... If this is not a product easily purchased, what is the chemical make-up (formula) and I will make my own batch.

I'm having a similar issue with trying to find Sodium PolySulfide which I have read here, also will turn copper black.

I want to blacken the engraving on a copper piece ... polishing the surface, and have the black engraved letters remain.

I do not want to use Liver of sulfur (due to the smell) but am open to any other suggestions ... I was hoping to obtain something very cheap that also has some sort of shelf-life (most cost-effective). The pieces I am engraving/etching are an oval of 1/2" x 1"

Thank you

Chuck Van Dien
- Port Saint Lucie, Florida, USA
December 4, 2017

A. Hi Chuck. "Zinc purifier" and sodium polysulfide are probably pretty much the same thing. If you google for "plating process supplier" or "plating chemicals" with your location you will probably find distributors of plating chemicals who can offer zinc purifier to you. If you'd rather look for sodium polysulfide, topic 1109 discusses the sources for that in depth. Good luck.

Regards,

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

A. Use liver of sulfur liver of sulfur [on eBay or Amazon] . It will turn copper or silver from brown to black . You can order it from Gesswein. This is an excellent product and works great. Although it does smell like rotten eggs.

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 Bluing [on eBay or Amazon]. It's advertised as a blue/black oxide finish for steel but it is very effective on brass/copper. Brasso [on eBay or 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.

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 [affil links]. Look at the label and see if it contains sodium bisulphite and other sulfur derivatives. These are very similar to the chemicals in Liver of sulfur.

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.

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

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Palmolive dishwashing liquid [affil links] actually worked. Can't believe it. A few minutes and it looked like it aged months - and a nice brown. Thanks for the great tip!

Jeff Mucci
- Pittsburgh, Pennsylvania
January 25, 2010

A. Hi, Ellen. If the coating is brass lacquer, you can remove it with with lacquer thinner [on eBay or Amazon]. If it's a more durable coating, you can probably remove it with Aircraft Stripper which will not hurt metal, but is really noxious stuff absolutely demanding goggles [on eBay or Amazon], rubber gloves [on eBay or Amazon], and truly excellent ventilation (be sure to consult recent EPA releases before deciding whether to use it).

Regards,

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.

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 Commercial Line [on eBay or Amazon] 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.

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,

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 [on eBay or Amazon] or lacquer thinner [on eBay or Amazon]. Then you can darken it as above. But easier and safer, if not as permanent, might be a Rub'N'Buff [affil links]. Good luck.

Regards,

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.

A. 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, but 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 too :-)

Regards,

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,

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,

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 [on eBay or Amazon]. 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,

A. Hi, Diane.

A wax rub is probably the fastest and easiest route to the color you want while maintaining a real metallic look.

but the durability of that approach is quite questionable depending on exactly what you mean by "handles". Good luck.

Regards,

A. Easy method for darkening brass:

I wanted to darken my antique brass hardware that had a finish on it. I needed to get the finish off first which I did with fine steel wool after sand blasting. I guess you could use acetone [on eBay or Amazon] or some kind of paint or finish remover. I tried Palmolive but it didn't work. I ended up using ammonia and it was really simple. I put all my hardware face up on a cookie sheet inside a plastic trash bag. Lay the trash bag on the counter and slide the cookie sheet in. Fill a glass bowl with a couple cups of ammonia. Place the bowl of ammonia in the center of the cookie sheet. I also place a heavy drinking glass upside down in the center of the ammonia bowl to keep the bag up and away from the hardware. This way the fumes from the ammonia was able to circulate. I then tied up the bag and left it over night. In the morning the hardware was perfectly aged. It looks A bit dry so I am going to rub a little polish on it to just liven it up a bit. This method was simple and quick.