Ammonia in brass cleaners


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Dickee Bear
September 15, 2005, 10:08 PM
I've heard it over and over again that you should NOT use any brass cleaner that contains ammonia because it 'weakens' the brass. What or where is that alleged fact shown to be true? What is the scientific substatiation that establishes ammonia to be something that weakens brass?

Dickee Bear

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pauli
September 16, 2005, 12:41 AM
What or where is that alleged fact shown to be true?in chemistry textbooks?

ammonia reacts with copper *and* zinc. it causes brass to become brittle, there's really no way around it.

bogie
September 16, 2005, 12:48 AM
Because wearing small chunks of brass in one's face is NOT a fashion statement.

ulflyer
September 16, 2005, 07:13 AM
Regarding non-use of amonia products, I've read that some guys use auto polish in their tumblers to help clean brass. When I first read that I thought it was a great way to use up some of that excess polish I had, plus its a lot cheaper, so I looked at several diff containers of polish I have and none of it says it does, or does not, contain amonia, so I haven't used it. Wonder if the product "Brasso" has amonia in it? The can doesn't say and I have a bunch of that too. Oh well. :(

bogie
September 16, 2005, 08:02 AM
Brasso = Bad.

Guys. Unless it's for a semi-auto or auto that absotively posilutely must work, just de-crud the cases... A tumbler with pet-store media (larger chunks don't get stuck in primer holes) works fine - you don't even need to add anything.

If you MUST have perfect slick stuff, load plated brass.

With my bench guns, I just use a little 0000 steel wool on the necks. Twist, and done. With the rest, fast tumble to cut the crud, and done.

jacobtowne
September 16, 2005, 11:30 AM
Brass is made of copper. Ammonia is used in Nitro solvents to dissolve and remove copper fouling in bores.
JT

BigCheese
September 18, 2005, 10:13 AM
When brass is under tensile stress, such as the mouth being belled or from expansion after firing, it can crack in the presence of ammonia. This is known as "stress corrosion". This occurs under a tensile stress less than that needed to fracture the brass mechanically, and with a relatively mild corroding medium that does not cause visible attack of the surface. However, with the combination of the two, cracks develop. Stress corrosion attacks the boundaries between the individual grains of the brass and causes them to separate.

The attached photo shows a brass part that failed in exactly this manner. I have encountered this type of failure on numerous occasions, as a metallurgist operating an independent test laboratory. (website rdkraft.com).

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