Removing oxide from old blackened brass

A. Hi Jason. I think, but don't know, that a copper/brass 'brite dip' based on sulfuric acid and peroxide will work, so we appended your inquiry to a thread on that subject.

If you wish to try it yourself, that's your choice. But just in case you didn't know, there are plating and finishing job shops everywhere that specialize in such issues and will already have the setups and experience.

As for wanting your posting to be in 'Section 4c', no problem. This is a curated website with all implementations ultimately done manually rather than by any form of AI :-)

Luck & Regards,

A. Hi Joseph.

Companies who sell brass polishes have achieved enough success to market commercially viable brass polishes, but they are limited to what is safe to sell to consumers, and their polishes therefore are apparently not strong enough for your need :-)

From that, my guess (that's all I can offer!), is that your friend used oxidizing acids in the mix, i.e., chromic acid, nitric acid, or sulfuric acid plus peroxide, which suppliers of commercial polishes cannot include because they are too dangerous for consumers. Whereas it was practical to use chromic acid years ago, it no longer is. Nitric acid is very nasty stuff and I can't make a solid suggestion about the ratios. So I would suggest that (on an old and discardable piece of brass test metal), you try a mix of dilute sulfuric acid and hydrogen peroxide: it's a powerful 'brite dip' for brass.

Readers, remember this was written for an expert, and others should not attempt it without training in the potential dangers! Hydrogen peroxide (as well as chromic or nitric) are powerful oxidants that can start fires and create explosive mixtures. Good luck!

A. Try next solution: 30 ml sulfuric acid
60-150 ml hydrogen peroxide
800-890 ml water
20 ml ethyl alcohol
Hope it helps and good luck!

A. When he gets around to polishing light rings make sure his health insurance is paid and he has a ride to the hospital. And a truly devoted friend as he might also have trouble cleaning his rear end with two broken hands.

aThanks, Joseph. I apologize if any of the responses offended you because I am certain that we all would be very impressed with your facility and the things you've accomplished there. I sincerely believe that with your decades of hands-on experience, you know a hundred times more about the subject than I ever will (or most of our readers).

I'm certainly not claiming that Brasso or Flitz will work when you've found otherwise! But when no commercial brass polish works, although they were specifically developed & marketed for this, and I'm sure the brass polish manufacturers can't all be stupid, my best guess must remain that it requires chemistry unsafe for marketing to consumers. My feeling is that a mix of sulfuric acid and peroxide will come closest to what your friend mixed all those years ago, and Goran (a metals conservator for a museum) concurred and offers a formula for you to try.

This bright dip solution (probably a bit different and with stabilizers incorporated) is commercially available from Electrochemicals in Minnesota or from John Schneider and Associates, and perhaps from other distributors of plating chemicals who may be listed in your yellow pages; it's widely used to brighten copper and brass in the electronics industry which you mentioned. Suppliers are concerned about liability and product stewardship so I don't know whether they will sell to you or if they restrict their sales to commercial metal finishing businesses. If you can't get it there, try googling 'hobby plating' and see if those suppliers have a "sulfuric-peroxide brite dip for copper & brass".

In Ellisville (near St. Louis) you will find The Goad Company, a distributor of metal finishing chemicals & equipment who may be able to provide more personal help with these issues. Please continue to post your questions and people will hopefully continue to try to answer them. Best of luck, and sorry again if it seemed like I talked down to you -- because I realize that I know little about this and you know an awful lot.

A. If the fella who needs his horn stripped in order to do work on it is STILL out there ... Sorry I did not respond sooner! I know that is silly to say BUT I failed to get a notice of a response! Sorry. The restoration business goes on and will indefinitely ... I hope.
First thing to do is to remove the finish that covers the horn. Usually it is a clear coat. Urethane, lacquer, or brown tarnish. Unless someone tried to Paint it! Usually black. I have seen corrosion so thick it appeared to be paint. I have used plain Muriatic acid to remove this coating after soaking in a paste paint remover gel ⇦this on eBay or Amazon [affil links] first overnight. Then I useacetone ⇦this on eBay or Amazon [affil links] Warning! highly Flammable! or lacquer thinner ⇦this on eBay or Amazon [affil links] Warning! highly flammable! to soak off any more top coatings. Pour a little Muriatic acid into a plastic cup or a cut off plastic pop bottle. Using a 1" flat brush I apply it to the base metal. The brown coatings will melt away BUT it also eats away at the zinc in the yellow brass turning it a slight copper color. So do not leave it on too long! This was why I asked for the formulation of a different mix in order to stop this from happening. The people who could probably help on this situation would be people who restore Musical instruments made of brass. I only knew about the BRIGHTENER I was asking about a few years ago on here to Ted as I once worked in a computer leads and plugs manufacturing facility. The chemist there and I were friends (1985) and he made up a mix for me to use on a early (09) car headlight restoration project I had at my home shop. It WORKED!!! I STILL would like to know a simple good formula as I STILL have NOT done the remaining brass restoration I have yet to do. I WILL do them though.
Years ago there was also a product from Amway that polished the brass very well. THEN... Brasso ⇦this on eBay or Amazon [affil links] or other products would work to bring out the real shine on those early brass parts I do.
Joe in Branson, Mo. USA

Hi Joseph.

The most powerful stuff for removing organic coatings is probably aircraft stripper (methylene chloride), and it's very toxic, requiring gloves, goggles, and good outdoor ventilation. It does not damage metals.

Removing the brass tarnish probably requires -- I offer my same opinion for the 3rd time -- an oxidizing agent like nitric acid or hydrogen peroxide. Please try Goran's formula if you haven't. Good luck.

opinion! The loss of the work ethic is obviously a very complex issue. But part of the problem is the fact that survival comes first, and people need good paying work, which is hard to find these days because we've shipped the jobs overseas to $2/hour labor. I overheard some men talking yesterday, with one saying that as a welder with 15 years experience, he simply cannot work for $9.50-$10 an hour and no benefits, but that is all he has been able to find for more than a year now ... he's right. The 0.1% and our politicians whom they've bought have a profoundly broken concept of what free trade means -- they're not talking about trading cotton & iron for silk & spices, but about scouring the world for slave labor.

Regards,

A. You've got an ancient and heavily tarnished fire extinguished there.

Automobile buffing compounds will take a very long time to remove it.

Get a small can of Brasso ⇦this on eBay or Amazon [affil links] , and a large supply of elbow grease.

A. Your fire Extinguisher is EXACTLY why I asked my first question on this forum to Ted. I believe it HAS been answered above by the fella from Croatia. THANK YOU and NO I haven't tried it yet. I am still working on OTHER projects yet.
Again the first thing I would use is the Muriatic Acid and a 1" brush. See comments above. Do NOT leave it on more than a couple of minutes!! Try using some phosphoric acid with baking soda [in bulk on eBay or Amazon [affil links] on a towel to scrub the brass. Dip the towel into the phos and then picking up a little of the baking soda and scrubbing it in small areas. Use ALL recommended safety procedures. Nitryl Gloves, face shield, and outside ventilation with a slow speed fan blowing it away from you.
I sometimes forget even though we are talking TO professionals these forums are accessible to the hobbyists.
Next USE the Brasso ⇦this on eBay or Amazon [affil links] , Flitz ⇦[this on eBay or Amazon affil links] , and or the other products for sale to the general public.
I am SURE that when you finish your extinguisher can body you'll understand WHY I made this post!! Now multiply your job by 4 and you will have what it takes to do only ONE early brass car!!
Good luck. Sorry if I did not answer you sooner. The forum does not send out a notice to reply.
Joe in Mo.

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Ed. note re. 'notice to reply': If a followup question is asked of a particular person and within a reasonable time lapse, we do try to send a notice to the person who was asked the question. In this case the fire extinguisher question was not directed to Joe, and he opened the thread 8 years earlier, and so we didn't advise him. Sorry! We'll try to remember to advise you of any additions to this thread.

A. Me again from Autoworld in Branson, Mo.
Concerning the people who have chimed in about buffing or using Flitz or Brasso. WOW you guys have never used that stuff on any corroded brass!! If you did then I pity your arms and fingers afterwards. I have used Phosphoric acid in solutions of approximately 10 -15% with distilled water. You can find it used for bleaching potatoes for the fast food industries. Used only at the source of farm production or in the fruit cleaning... again at the farms. Brushing this onto the tarnished brass removes that brown coating in just a few minutes. Start at the top and continuing downwards rinsing the top finished cleaned brassworks clean of the acid. Any acid left on the surface is not good and turns the brass green. So remove it completely. NOW you guys and your Flitz and or Brasso can go to it with much success in bringing out the shine. This is how I have done my old brass radiators for many years. Other brass autoparts too. But this was not the answer for my original search. I was searching for a dip that would clean the whole lamp. And then a brightener.