Acetone & Green Slime

A few days ago, in a thread that I can not remember the title of, I suggested trying Acetone to remove Green Slime. Has anyone tried it? Did it work or not?

Ron…The thread was T116 Gone Bad…a few threads down the list from this one…Phil Butler was the author…Randy

How come I only see green slime in my American-made ammo? Maybe my collection is not big enough.


I haven’t gotten to the inside of the case yet. I’m still trying to remove the crud in the neck/mouth crimp area. Acetone, MEK and lacquer thinner don’t touch it. I’ve got it soaking in some stuff called Prolix right now. Will see what it looks like tomorrow.

Phil–So much for my Acetone idea. Acetone is such a good solvent I figured it was worth a try. Keep us posted on your tests. I remember a few years ago there was an article in the IAA Journal with a chemical analysis of exactly what the Green Slime was and how it formed, but I don’t recall if there was any mention in how to remove it. If I remember correctly, the article said unless you removed the powder BEFORE it started to break down that there was no way to prevent it.

What is “green slime”? I can’t translate it into italian… it comes out like " green mud"


Another term for slime might be “ooze” (in the noun form rather than verb). Mud is not far off. For sure it looks like the green stuff on Phil’s grenade cartridge in the previously mentioned post (.30 Light Rifle T116 Gone Bad). The May-June 2005 issue of the Journal (#443 pg. 52) has an article titled “Case Corrosion” per the index. This may be what Ron recalls? Sadly, I wasn’t “card carrying” untill #447 and that one’s in the “dark territory” as far as the Back Issues disk…

Would someone that may have that issue handy be so kind and tell us the basics on what happens chemically to ruin cartridges like that?


Ah , now I understand . In italian would be “ossido di rame” , a copper oxide

Brass is an alloy that contains copper too .With time the elements of the alloy can separate and copper comes on the surface of the object . This firstly turn to green , with the “flowers” also seen on pbutler’s cartridge , and then turn to black

If you scratch the green slime , there will be a black stain below it

Another cause could be the powder contained into the cartridge

The green color is for sure due to the copper in the brass getting ugly (Verdigris of sorts). I’m curious about the acidic components generated by the powder breaking down and why they are formed so dramatically in some instances. If all things are equal (say straight nitrocellulose single base, all usual deterrents to decomposition added to the powder and no process errors in manufacture) does this happen to some cartridges because they are exposed to too much heat? (“Left in car while stopped for lunch on way back from show in the summer sun” kind of thing?)

Keep your powder dry.
Keep your (smokeless) powder cool…?


What I use to remove the green ooze on the brass, caused by the powder acids, is a solution of simple sodium bicarbonate in tap water. Leave the attacked part covered by this solution and it goes off with no problem. A word of warning: this cleaning does not prevent the slime to show again if the offending powder is left inside the case.

You might also try plain old Coca Cola. The original, not Diet. It works on some kinds of verdigris.

Dave, I think the reason that some cartridges are more prone to attack lies in the powder. If the powder is not thoroughly washed to eliminate all of the unwanted acids the copper in the case and bullet will be attacked a lot sooner. That’s one reason that you’ll find certain cartridges, all made at the same time, to be breaking down while others made a year sooner, or later, are just fine.


What about using a bore cleaner that is a copper-killer for the green stuff, like this cleaner:
I have used this stuff before, it is very toxic and noxious, but it cleaned a barrel remarkably well.

[quote=“RayMeketa”]You might also try plain old Coca Cola. The original, not Diet. It works on some kinds of verdigris.

This is probably due to its contents in phosphoric and carbonic acids. Diluted phosphoric acid was used in Spain years ago to clean fired artillery cases before reloading them.

Its particularly bad on pistol ammunition that is carried for any length of time in leather belt loops. The oil in the leather is slightly acidic and attacks the brass.
This is a problem for law enforcement types because it can build up to the extent that it prevents the ammunition being loaded into the chamber. This could have serious consequences for the officer concerned altough most officers I have seen also have a couple of speed loader pouches on their belt and the number of occasions when they would need more than eighteen rounds must be very low. Still, these situations do happen

With leather contamination the build up is particularly thick and waxy.

Ammunition often sits for years in those loops without ever coming out and the ammunition can stick to the loops if it is left in for too long…

It is, I believe, the original reason for nickle plated cases being introduced for calibres like .38 Spec duty ammunition, Perhaps someone would correct me on this if they think I am wrong about the origins of nickle cases or has better experience than me…

The “green slime” usually at the mouth of cartridges, is due to a combination of Powder breakdown into Nitric Acid, remains of “unwashed” Sulphuiric acid (a "drying agent in Nitro Powder manufacture), and Moisture from both the atmoshpere and the Powder breakdown.
The acids attack the Copper and the Zinc in the brass, making a complex mix of Copper Nitrate, Copper Sulphate, Zinc compounds and Nitrocellulose/Cellulose degradation products…hence the “Slime”.

Since this slime is acidic,in nature, an Alkaline cleaner such as Bicarb. of soda (NaHCO3) or Washing Soda ( Na2Co3) will clean it away…but the offending Powder should be removed. Vinegar, being (mildly) acid, will also removed all the salts… But both processes will show up “Pink” Dezinced areas in the brass. (Zinc is preferentially removed before Copper)

Occasionally the real culprit is deliquescence of the Chlorate priming in the Powder, which starts the Nitro Acid breakdown (Very common in US Cartridges of WW II and before). So a “slimy case” will also have a "leaky Primer as well.

Solution, Dismantle the case if possible, Wash in Bicarb or Vinegar, leave some Vinegar in Primer for 24 Hours, to deactivate the primer, wash in Hot water and dry. Then one can re-assemble the Empty round, if the neck has not been too far damaged.

The green slime in cartridges held in leather Loops or Pouches for a long time is due to the Chromic and Oxalic Acid tanning compounds.
Again it is a Copper Chromate and Copper Oxalate ( Poisonous to man and beast, in quantity)…it was this “Verdigris” on the leather-carried Spanish .43 Reformado ammo in the “Span Am” war which gave the origin to the Cry of “the Spanish are using Poison Bullets” (Hearst newspapers). It was more the Lead bullets combined with the Poor medical services in Cuba which led to more fatal outcomes with .43 wounds than with FMJ 7mm Mauser wounds ( See Lagrande-- “Gunshot Injuries” 1914, rev. 1917).

Storing cartridges in PVC bags also leads to “Vinyl Chloride green slime” as well ( PVC will break down into Hydrochloric acid over time, especially if a metal like Brass or copper is present.

Doc AV
AV ballistics.

Vince–I agree that the problem of corrosion with brass cases and leather belts was the original reason for nickel plated cases. However, nickel plating also serves at least 2 other purposes. One of the earlist plated cases after the .38 Spl. and .357 Mag. was the .38 Super ACP. It was plated to identify it from the .38 ACP. Also, the nickel plating acts as a “lubricant” to make extraction easier in higher pressure rounds.

Deputy Barney Fife never had a problem with dirty bullets! ;) ;)


In regards to the removal of the powder to prevent the Green Slime problems, you of course lose the feel and weight of the loaded round when you reassemble it. If this is important to you, an inert powder substitute that I have found that works well, and has approximately the same density as smokeless powder, is Decorative Sand used in fish tanks or aquariums. It comes in black if you want, or in many colors. I use a bright blue or green color so if someone disassembles the cartridge in the future, they will know it is not gun powder. It is available at any pet store.

Thank you DocAV for the technical input on the “green slime” condition. One has to be on guard for this all the time, I suppose, as a cartridge can be looking “real purty” on the outside while it’s rotting all to heck on the inside…I have to wonder, in 50 or 100 years from now, how many WWI era complete cartridges will remain in collectable condition? Will tearing down cartridges and removing the powder become the rule in the future as more and more heart breaking losses are encountered? Future collectors may look back on our time as a golden age of collecting loaded specimens…

I’ll try to remember to enjoy the moment!

Also, you’re right, Ray. Deputy Fife’s one round was probably well polished and free of debris riding around in that shirt pocket.


Thats bad news about the PVC bags then as lots of collectors use plastc bags routinely.
Does this include the normal plastic pop top bags most commonly used? If so what should be used instead?