What's wrong with my brass?

[Silver02ex]

I bought about 1000+ 45 ACP brass from Leo Brass awhile back. After 5 hrs in the tumbler the stain that's on the brass is still on. I took a few out and try to scrub it with dawn and hot water to see if it will come off, still no luck. No matter what I try, nothing seems to work. About 1/5 of my brass are this way. Any idea why it looks this way? I never had a problem with factory rounds that are fired and clean. There doesn't seem to be any issues with loading or cycle in the gun, just cosmetics. Here's some pics:

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[HappyRoman]

Known as water stain marks,, probably not ever going away. When brass has been wet, it will sorta corrode, this is like brass rust. Brass does not really rust, that's an iron thing, but it does corrode and this is what it can look like... if it's deeply pitted, should not overload, and watch between each firing. If this is truly on top of the brass, could use a solvent to dissolve it possibly, like alcohol or lacquer thinner.. Good luck

 

[Silver02ex]

Sounds like the place I bought it from must have got them from an outdoor range and let them sit for awhile.

 

[NJG26Crux]

Get some BRASSO or equal and try by hand ... if it works and is a liquid not a past try a run with it in your tumbler. Been around alot of brass im the marine industry .... takes alot to pit. Let me know how it works for you.

 

[Silver02ex]

I tried Brasso, white vinegar, ketchup and anything under the sink I can find. I got a call from Leo Brass today and was told that it was in a batch that was sitting soaked in the rain. However he would send me some extra brass on my next order to replace the stained ones.

 

[NJG26Crux]

BTW most polished brass fixtures have a eurathane (old school laquer) finish to retard tarnish, this must be stripped to polish (some polishes have an agent to do this) .

A buffing wheel on a grinder works best for this. To keep it bright most polishes also have wax to keep oxygen away. Bright brass or a gummy gun?

 

[NJG26Crux]

Off topic why does the forum replace r e t a r d (without spaces) with bubblegum? I used the word correctly and without any offence. The PC police are getting on my last nerve. Like last week I was on a 3 hour layover in Dallas and couldn't find one gun magazine!

Rant over... for now... I guess... LOL

 

[Nwcid]

DO NOT USE Brasso on cases, brasso and brass cases - Google Search

 

[AMProducts]

This kind of staining usually happens when the zinc in the surface of the brass corrodes out and leaves a copper deposit behind which rapidly forms the stable black copper (II) oxide, the best ways I have found to remove it involve chemical and physical means at the same time, usually citric acid and stainless tumbling media.

To an extent you can also use a more aggressive tumbling media such as walnut, which will not give you the same "high gloss" finish that corncob will. However, you can tumble in corncob after tumbling in walnut. Whatever you decide to do, be sure to use a polish that contains a wax, dillon's polish does this, so does nu-finish, the wax will help protect the surface from re-oxidizing and will keep them bullets looking pretty.

Also, do not use brasso or any other ammonia based compound to clean brass, for two major reasons 1) it contains ammonia which screws up brass 2) it does a really crappy job. If you just want something that is very aggressive at cleaning brass, you can use either baking soda, or toothpaste. For toothpaste, mix it up with some water until it's thin enough to drizzle on the media, you can use alcohol for this. However, I would just recommend using something designed for polishing brass shell casings like rapid polish, or if you want to experiment and save some money you can try nu-finish car wax, a lot of the guys on the castboolit forum are nuts over that stuff (have not tried it myself). Berry's is also making a case polish, they sent me a bottle after SHOT this year, but I havn't had a chance to try it out, but it looks very promising (contains wax).

 

[deadshot2]

If it shoots OK, why bother. If appearance is that important, just segregate it and use it when you're shooting in a field with tall grass. That way you won't cry as much if you loose it

I've got a whole bunch of .223 brass like that. I save it for Gravel pit shooting where the ground is littered with old Wolf steel brass and I lose about half what I shoot.

If your supplier is going to make good on the water stained brass I wouldn't put another thought to it. Just shoot and enjoy. Besides, nobody can see the marks when it's loaded in your firearm.

AMProducts-- NuFinish Car polish is great for brass cleaning. Actually works better than the polishes sold specifically for brass tumbling. Since I now use Stainless Pins, I don't use much polish of any kind now but every once in a while I shine up some cases after they come out of the pin process. Just for show off purposes I guess.

 

[Gunner3456]

This kind of staining usually happens when the zinc in the surface of the brass corrodes out and leaves a copper deposit behind which rapidly forms the stable black copper (II) oxide....

This. Brass is a mixture, not a true alloy, of copper and zinc. The zinc is very soft and can be dissolved from the copper. Considering how thin a case really is, If I could feel those spots with my fingernail, I'd toss the cases.

This is also a good reason not to use certain chemicals when cleaning brass. I wouldn't use a high alkaline (ammonia) or an acid, even citric acid.

If it matters, the term for this is dezincification, and the erosion leaves behind a thin, copper rich and weakened spot.

Just my $.02.

 

[AMProducts]

Brass cases respond just fine to alkaline cleaners, but cleaners that contain ammonia are a no-go because copper forms complexes with ammonia. These complexes behave the same way iron (III) oxide behaves, creating crystals that are larger and less stable than the base metal, which leads to scaling. This is the same way ammonium sulfate is used to apply a patina to bronze statues.

In my experience, these layers are very thin, and once you can break through the mechanically harder layer of oxide into the softer layer of copper, using the right polish will return your brass to a more even sheen.

 

[Gunner3456]

Zinc is a very reactive material, and when removed from brass the underlying copper is quite weak. Zinc's atomic bond is weak compared to most metals and is is easily lost. This can happen with either acid or alkaline liquids if they are fairly aggressive.

Zinc is never used with strong alkalies or acids in industry because it quickly corrodes. BTW, iron (III) oxide is also sometimes called rust.

Why risk it? The already thin brass wall thickness has been reduced, and the strength is compromised not only by thinning, but metallurgically.

IMHO you are showing an injudicious view of ammunition which would concern me about anything you produced.

 

[AMProducts]

Copper and it's alloys do not undergo destructive oxidation in the same way iron alloys do. Under strong chemical conditions, zinc will be removed from the surface metal, but not be removed from the base metal, because it's a solid object. This is a very similar process to what is done commercially with stainless steel, it's called passivation, and yes it selectively removes individual molecules from the surface. This process will not compromise the internal structure of the material, because it is strictly a surface effect.

Additionally, in tests with a diamond point hardness gauge we did not see any change in hardness as a result of acid or base treatment of the casing, the only treatment that did have any effect was heat.

Water staining is a common problem when manufacturing brass, if removing the stains is as serious an issue as you imply, then you had better stop shooting, because no brass or ammunition is safe.

 

[Gunner3456]

Copper and it's alloys do not undergo destructive oxidation in the same way iron alloys do. Under strong chemical conditions, zinc will be removed from the surface metal, but not be removed from the base metal, because it's a solid object. This is a very similar process to what is done commercially with stainless steel, it's called passivation, and yes it selectively removes individual molecules from the surface. This process will not compromise the internal structure of the material, because it is strictly a surface effect.

Additionally, in tests with a diamond point hardness gauge we did not see any change in hardness as a result of acid or base treatment of the casing, the only treatment that did have any effect was heat.

Water staining is a common problem when manufacturing brass, if removing the stains is as serious an issue as you imply, then you had better stop shooting, because no brass or ammunition is safe.

There is a big difference between water stains (which may if whitish or gray be zinc but harmless) and pits that I can feel with my fingernail.

A said that if I could feel the pits with my fingernail I'd toss the brass and I would. Please stop trying to dodge and weave on the subject.