Case Corrosion

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JSmith

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A few months back I bought 300 cases of Starline from my LGS and set them aside until I had time to do something with them. This morning I was counting them into 50-count bags and found a few that were corroded to one degree or another. The first two cases are corroded all the way through.

No way am I going to shoot these but I wonder if anyone here can tell me what might cause that. I don't think it was anything I did (which was basically nothing) and I've never seen it before in any of my purchased brass. I look forward to learning something about brass metallurgy!
 

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Most likely, they got very wet, or got a chemical spill on them in shipping.

Whatever the cause, it isn't normal without some outside influence acting on them.

rc
 
Without having them in my hands to look at, it's impossible to say, You did say you bought them at a LGS. Were they in factory sealed bags?? If not I would guess they had been cleaned with some chemical that etched them away.

Looks like parts of my boats motors:uhoh:
 
snapshot762 said:
Looks like chemical corrosion to me.
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Agree, like exposure to salts. The salts could have even come from sweat / perspiration on hands that handled the cases. Compound salts or other chemicals with some high humidity (over 70%) and the effect looks like a few of those cases.

Trash them and carefully inspect the remainder.

Ron
 
I probably have 6-8K of Starline cases sitting in boxes both loaded and new. I have been using them for close to 20yrs possibly more. In that time I have had some that had spots, splotches and some discoloration, but nothing ever like that.

Personally, I would sack them up in a zip lock and ship them back to Starline with the lot number if it's on the package, and let them know you purchased them new and they wee in that condition when you opened them. I haven't had but one or two instances where I had any complaints with their cases but in those times they shipped me replacements to cover them.

Its at least worth letting them know about it and see what they will do for you. I'm sure they will want them though to see if it was something they did and what might have slipped through. They have a really outstanding products and reputation and I doubt they want either being tarnished.
 
Further research indicates that type of corrosion in brass is known as "dezincification" and occurs when that metal selectively leaches out of the alloy.

Why Dezincification Occurs Copper-zinc alloys containing more than 15% zinc are susceptible to dezincification. Zinc is a highly reactive metal, as seen in its galvanic series ranking. This reactivity stems from the fact that zinc has a very weak atomic bond relative to other metals. Simply, zinc atoms are easily given up to solutions with certain aggressive characteristics. During dezincification, the more active zinc is selectively removed from the brass, leaving behind a weak deposit of the porous, more noble copper-rich metal.

Conditions favoring dezincification are contact with slightly acid or alkaline water.

http://events.nace.org/library/corrosion/Forms/dezinc.asp​

The cases in the photo were the only ones in the bag to exhibit anything like that. The other 294 are all bright and shiny, inside and out. I'd guess, if anything, that some rejects got spilled in with the production. Mistakes happen sometimes.
 
Nope. There's some in a capped jug under the sink in the next room, but not nearby.
 
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