What's the best way to clean heavily tarnished brass?

[Quatermass]

Hi, what's the best way to clean heavily tarnished brass, is there a better (quicker) way than just elbow grease and brasso?
Does anybody have any experience with ultrasonic cleaners, if so is there anywhere to hire/borrow them?
Thanks in advance.
Patrick.

 

[Dronic69]

Hi Patrick,

For heavily tarnish cases like yours, the easiest way would be to use an acid solution to strip the oxidation layer off and then polish using Brasso etc.

Basically brush /wipe on for a few minutes and rinse off - you know when it the oxidation layer is off when you see that really funny shiny new brass virgin appearance - off course results will vary depending if the case has been in salt water then expect the pinkish tint (copper) due to the zinc being leached out of the brass etc.

You can search the forum as there are numerous posts on this topic - here's my one from back in 2010 (post #10):

Are they worth it?

I am collecting on a budget; I am only interested in British first & Second World War. Are the parts in the picture worth collecting in the condition they are in? Whats the best way of cleaning zinc and brass? Thanks for any help you can give me. Ted

www.bocn.co.uk

Lightly tarnish - Brasso / case tumbler
> Mildly tarnish - household products as suggested above (vinegar is a mild acid), haven't heard of "Brown Sauce" before, but probably has [FOOD ACID 330] which is "phosphoric acid" (Coke).
> Heavy tarnish - I use the following magic "Enhanced Coke formula":

55% Phosphoric Acid
25% Glacial Acetic Acid
20% Conc. Nitric Acid

However the combination of acids may be hard to get - although just buy a couple of cans of coke (phosphoric acid) as highlighted in this post:

Brass cleaning

Hi, has anybody got any suggestions on the best way to clean brass i have a 75mm case thats been laying in the ground for 90 years its solid and i know it wont be brilliant when its clean but i don't like to throw it out i have tried vinegar on the base the case looks as though its going coppery...

www.bocn.co.uk

Cheers
Drew

 

[Quatermass]

Thank you Drew, I've got it soaking in Coke.

 

[Alpini]

Pure Phosphoric acid works very well, is easy to get, inexpensive, lasts long and is compared to many other other acids nearly harmless. Coke contains a very small percentage (it not even tastes sour) and on your example to clean would barely show any result. I use H3PO4 in 75% quality and dilute 1:1 with water and apply it with a brush. Consistency is like syrup so it won't flow away immediately. Wait 5 to 10 minutes and then clean with scouring milk. It won't leave scratches as a wirebrush does.

 

[Quatermass]

Thank you Alpini, Phosphoric Acid at 75% is difficult to find in the UK, 20% seems to be available but anything above that strength is regulated by the government I believe.

Patrick.

 

[Alpini]

Strange - thought it's worst in the EU but here you can easily buy a 10 kg canister without a problem and chemicals are highly regulated in the EU. But as I understand they regulated only those acids which may cause cancer (like sulfuric acid) or acids which can be used to produce explosives (both sulfuric and nitric acid). But why H3PO4?

You may still get it as rust remover. A rust remover should contain a good percentage to work because rust is solved much harder by H3PO4 than the oxide layer on brass. But I haven't tried it yet. What I tried is H3PO4 based toilet cleaner but it works much slower compared to pure H3PO4 and smells terrible .

 

[Alpini]

Btw. Coca Cola contains 170mg H3PO4 per 1000 ml (that's 0,017%) and maximum allowed are 700mg per 1000ml in beverages - that's nothing for a technical usage.

 

[Darkman]

For really tarnished cases I fully immerse in brick cleaning acid (hydrochloric acid) for literally only 10-20 seconds. Then neutralise in a 10% bicarb soda & water solution for a few minutes. Final step is to polish with very fine (0000 grade) wire wool using plenty of water for lubrication. This will give a very clean and bright brass finish without that very unnatural highly polished shine obtained with Brasso. (I NEVER use Brasso on cart cases.) But as Drew mentioned, if the case has been buried or water found it may come out a bit pinkish. This can be fixed but you need to remove the surface by polishing with fine grade emery tape.

 

[Dronic69]

Coke contains a very small percentage

Yep the rest is pretty much 7 x teaspoons of refined sugar - the diet stuff has worst chemicals. But then, drop a copper penny in it (or a piece of meat!) and see the affect
Further when I bought the chemicals (decades ago) - they were available via specialist companies - now too control and have buckles of getting conc. Nitric acid little alone phosphoric - they think you are setting up a Meth Lab! LOL
Yeah we live in a "nanny state"/ country!

 

[Scout Sniper]

Birchwood Casey rust and blue remover works wonders and takes seconds! Experiment on something 1st, and do not leave for too long.

Apply small amount with cotton buds, then wipe off. Buff with ultra fine wire wool and will look like new raw brass.