I have recently been looking for an inexpensive way to remove heavy tarnish from about 2K pieces of 5.56 brass. This stuff was allowed to get wet, and a lot of the cases were almost black. Well, I found it, and thought it might be of interest to others of you, since gas guns run so dirty...

Take 1 quart of vinegar and mix in two tablespoons of table salt. Immerse the de-capped cases for 15 minutes, agitating them now and again. At the end of 15 minutes, drop them into a container of hot soapy water. Run enough water into the container to get rid of the soap, remove the cases and allow them to dry. Tumble in your conventional tumbler once dry. (I add some of the Frankford Arsenal polish to the media; it seems to polish better than just fine ground walnut...)

I ran the tumbler for about 20 hours, but I can't tell any real problem from the extended time.

Looking at the way this stuff works, I can't tell any difference between it and the Birchwood Casey cleaner, Arrow, or any of the others. And best of all, vinegar and salt are cheap...

Try this, fellas. I think you will be very pleasantly surprised at the results.

Good to Know, Thanks!

you'll want to add in a rinse of water and baking soda to neutralize the PH of the acetic acid you made with the vinegar and salt.
I use citric acid much the same way and need no neutralizing rinse.

If I can't neutralize the small amount of vinegar held on the surface of the cases with the water bath, something is very wrong.

FWIW, this recipe came from the Frankford Arsenal and they make no mention of a neutralizing bath of baking soda.

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And best of all, vinegar and salt are cheap...

Even cheeper, leave out the salt, the results will be the same.

Only reason to add a bit of baking soada to the rinse bath is to be sure you've killed the acid inside the cases. If you don't care, no one else does. ??

The salt reacts to convert some of the acetic acid to hydrocloric acid which is more effective.
Unless you used an effective way to neutralize and remove the vinegar residue your cases will tarnish again very quickly. Simply washing the vinegar solution off with water will not do the job - I guarantee it.
With the Birchwood Casey product they do not retarnish.
The US arsenal recipe to clean brass was a 5% solution of HCL.
Vinegar is cheap, easy and safe but it is not the best solution - no pun intended.

Well, I will let all you smarter than I am guys know when my brass either develops holes in it because the vinegar inside it is still chewing, or when it all turns black because 20 hours in a tumbler full of clean walnut media after a soapy hot water bath didn't stop the tarnishing.

Sheesh...

dezincification

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Originally posted by 243winxb:
dezincification

Yes and they look pink.

I have to agree, any time spent in any kind of acid - no matter how dilute it is will affect your cases. The acid always attacks the zinc first. That is one of the properties of zinc and why they use it for ground plates on boats. It will dissolve faster than most other metals.

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Vinegar is cheap, easy and safe but it is not the best solution - no pun intended.

I know what the salt adds to vinegar's acid but plain vinegar is fast enough (for me) and does just as well alone. The "pink" tumbles off quite nicely, it was tarnish anyway so it's loss has no effect on the case's strength. All IMHO of course. After some 45 years of using straight vinegar and all of that after using the old arsenal formula a couple of years I just keep it simple.

Brass isn't porous. The very weak acid in vinegar can only affect the surface oxidation so it will not dissolve our cases. Or at least not without more than the week of soaking in vinegar as I experimented with decades ago.

I think you misunderstand the process. The copper is unaffected by the acid - your case will not dissolve or "get holes" eaten into it. The brass case will simply lose its zinc leaving you with a copper case instead of brass. This makes the case weaker because a brass case is stronger than one of copper. The pink color is "pickled" copper. Copper that has been stripped of "impurities" which are, in this case, the zinc that was part of the copper alloy adding its strength.

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The copper is unaffected by the acid

I think someone else misunderstands the process, too. If you have ever put brass cases into vinegar, then looked at the vinegar solution, you will see it is a beautiful emerald color. That color is due to dissolved copper acetate.

And you will find that the cases that come out of a 15 minute vinegar bath and are then tumbled are not copper colored. They are the same beautiful yellow color as brand new brass.

Somebody please tell me how a solution that contacts the surface only can de-amalgamate an alloy that is linked on a molecular level, and do it all the way through the alloy.

Methinks some of you could stand to read a bit of metallurgy. This is like the argument of tin coming out of solution during a casting session. It just doesn't happen. As Jim said, the brass is not porous, and the tarnish is only on the surface.

But then what does he know? After all, he has only been using this technique for 45 years...

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And you will find that the cases that come out of a 15 minute vinegar bath and are then tumbled are not copper colored. They are the same beautiful yellow color as brand new brass.

Ditto a case that's been vinegar soaked for a week.

Doub, your soapy water soak effectively does the same thing to the traces of the vinegar's acid as soda water, soap is mildly caustic, that's why it burns our eyes.

Jim, I have a pretty extensive background in Chemistry. And a man never shows ALL his cards...

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Jim, I have a pretty extensive background in Chemistry. And a man never shows ALL his cards...

I expose both of mine all the time!

1 pint of water, 1 cup of white vinegar, 1 tablespoon of salt, and 1 teaspoon of detergent is the old NRA formula. Use at your own risk.