How to Darken Copper, Brass or Bronze

A. I am currently using ammonia to darken a brass piano leg caster and it appears to be working. I've only had it outside in a sealed bag for about 24 hours. It hasn't reached the desired darkness yet but seems to be getting there. The first thing I had to do was remove the lacquer finish. I bought some finger nail polish remover as it contains acetone but it did not remove the lacquer, only seemed to etch it slightly. Having used it however, did make it easier removing the lacquer with sand paper. Once that was done, I put some ammonia in a disposable plastic storage bowl, used the lid to hold the caster and placed both into a small plastic garbage bag which I tied shut. Don't expect immediate results for a dark color using this method.

A. Hi Selena. I find that to be quite an attractive chandelier and hate to see you mess with it. But the first thing to find out is whether it's actually brass. If it's magnetic, it's not brass, and is at best brass plated -- which probably will not stand up to the darkening chemistry. If it's not magnetic, it could of course be aluminum or zinc; but you may be able to sense whether it's aluminum just from the light weight. If you're pretty sure it's brass, then this thread has worthwhile ideas for you. Good luck.

Regards,

A. Good day Heather.

I have some experience with electrophoretic lacquers and the stripping of the coating. I used a stripper which contained methylene chloride (which strips epoxy) and formic acid. (Atotech/Aquatone PS 400).
This stripper "softens" the coating, requiring mechanical removal of the coating with a brush, in a bucket of water.
This stripper requires a "layer" of water on the surface to prevent evaporation of the methylene chloride.
Great care must be taken with the stripper, as the formic acid is EXTREMELY corrosive. A splash on exposed skin will produce a burn/blister instantly.(Formic acid is the chemical which fire ants produce!)
I strongly recommend the highest degree of personal protection(when using any corrosive chemical) as a full face shield ⇦ this on eBay or Amazon [affil links] , activated carbon respirator ⇦ this on eBay or Amazon [affil links] , arms length rubber gloves ⇦ this on eBay or Amazon [affil links] .
Any chemical can be dangerous, but with the proper PPE, you can minimize the risk.
I hope I didn't alarm you.
Best wishes.

Regards,

A. Not to throw a wrench into your plans, but we PVD coat brass faucets on a regular basis and they are never lacquer coated. That is one of the great advantages of the coating -- it is pretty much a lifetime finish. You may be trying to strip the PVD coating off of the surface. I say this because PVD coatings are pretty much impervious to the chemicals you have used. PVD coatings can be stripped off, but it requires special chemicals in heated tanks in a properly vented facility. It is not done in situ. To add to the problem, you need a different chemical to strip a Ti-based PVD coating than you do for a Zr- or Cr-based PVD coating.

A. Hi Matthew. If you look at trophies you'll see that they are usually brass colored with engraved black lettering; high school rings will be gold on the raised areas and black in the recesses; jewelry too, and oil-rubbed items will be bright on the raised areas and dark in the recessed areas. This convention is because raised and exposed areas tend to wear and get shiny whereas recessed areas tend to retain their blackening and accumulate oxidation and dirt. For that reason I'd suggest that you entertain the possibility of perhaps making the placards brass colored with black engraving instead of the reverse. Further, it's hard to make different metals like brass and aluminum match by coloring them black or any other color because they have a different grain, texture, etc., and the colors will look different in different light (black anodizing is actually either very very dark blue or very very dark red). So I think you'll get a better match and more natural look with brass placards to match the shells -- but it's a matter of taste and I don't claim to have much.

The aluminum probably needs to be anodized and dyed black whereas the brass probably needs treatment with selenium dioxide as described in this thread. Good luck.

Regards,

A. Wynnie and Matt, the solutions you seek are the same. The process is a chemical which turns the copper element in each of your metals from a light brown through to a dark black when used with heat. Then apply lacquer and wax. Matt, your process is to dip the brass plaques into our chemical till black then application of vinyl film (letter mask) you will then get letters etched at trophy shop.

adv.
Call us at BarrysRestoreItAll if you need more info.

A. I might be a little late with the addition to this thread as I was researching something else and stumbled across this - I know that Bronzing Powders are short on supply but know that Access Chemicals Ltd in Tamworth, UK sell Brown Bronze Powder for "brush on" application as described above. It's a niche market and only a few manufacturers produce this product now. Apologies if this is of no use.

Hi Thomas. Thanks. We'll have to see how it goes since commercial testimonials on this no-registration-required, largely anonymous, site often go south very quickly :-(

Regards,

A. I ran out of the chemicals I've used to do this in the past. Came across this thread while searching for a household solution to the problem. Couldn't find what I was looking for so I started experimenting. I quickly discovered that a mixture of hydrogen peroxide & white vinegar ⇦in bulk on eBay or Amazon [affil links] works great! My hinges have been soaking about an hour now and look better than the ones I've done before. Keep in mind, these were raw brass, it won't work if they're lacquered.

A. Gail, great questions. The patina created on copper sinks is beautiful but fragile. Harsh chemicals and abrasive scrubbing will remove this finish.

adv.
A repair kit which we created to resolve issues like yours will quickly restore your beautiful finish. We also give you a hardy brown wax which will help protect your finishes. Frequent application of our wax will keep it looking its best. A call to our offices and we will help anyone with solutions for copper, bronze. and stainless steel

A. Hello cousin Amir. Try enclosing the item is a plastic bag with a crushed hard boiled egg, and tell us what happens. Thanks.

Regards,

A. Try this download free metals colouring and cyanide-free plating handbook ( 0 $!):
Hope it helps and good luck!

A. Researching historical metal processes, I came across the following 19th century references on Google Books for bronzing formulations. While modern products may be more efficient, those wishing to replicate the old finishes will hopefully find these helpful.

https://books.google.com/books?id=JsNEAQAAMAAJ&pg=PA354

https://books.google.com/books?id=XgshBQAAQBAJ&pg=PA149

https://books.google.com/books?id=tIcPAAAAQAAJ&printsec=frontcover#v=onepage

The last is a French treatise with several formulations for the famous French green bronze coating. You can copy and paste into Google Translate.

Thanks for the great references Craig!

The French book displays as pictures of text, rather than as cut&paste-able text; I do see a way of translating it (first download the book as plain text, then copy and paste the plain text into translate.google.com), but if someone knows a simpler way we'd like to post it. Thanks again!

Regards,

A. Hi Letty. That's really not so much a technical question (because you've already read that liver of sulfur, brass darkening solution, and several other materials will darken brass), as a question of whether you have the time & temperament, and the steadiness of hand to carefully apply it to "hundreds of brass nail heads" with an artists brush, covering each completely, without getting it on the leather. Further, if they're bright, they probably have a lacquer on them which you'd have to remove the same way first. There's an old saying that you'd need the patience of a saint.

Or just tape the open end of a plastic sandwich with a crushed hard boiled egg in it over one of the nail heads overnight and tell us what, if anything, happens. Good luck.

Regards,

A. Hi Barbara. I don't know what the article in question is, but can you try Rokushno patina on it and see whether it offers suitable/any contrast? Or maybe you can darken the whole thing and burnish/relieve the brass?

Regards,

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. Hi Nik. On the one hand plating shops antique brass and copper plating routinely; on the other hand, the sellers of brass darkening solutions warn you to use them only on solid brass, not plated brass, and your experience supports that warning :-(

I think the thing to do is to apply a tinted brass lacquer. See, for example, this page from G.J. Nikolas [a finishing.com supporting advertiser]: http://www.finish1.com/page_products_dyecolors.htm

Good luck & Regards,

A. Hi again. The instructions say to use only on solid brass, but I do not have any personal experience to say it can't succeed :-)

Have you tested the eyelets with a magnet or otherwise determined that they are not solid brass?

Regards,

  Oops, sorry for the delay. The things I'm looking to do are brass underneath but they are plated in zinc/nickel. I could remove that but its a bit of a lengthy process for something that I can't charge much for (the eyelet image was just to illustrate the colour required). I may have a play and see if I can work it out. Someone suggested plating a thicker layer of brass to counteract the effects of the antiquing fluid. I may just go with powder coating them a similar colour in the end if all else fails. Bah! Thanks for your help so far, I really appreciate it!