Kyle O Posted September 2, 2012 Share Posted September 2, 2012 Not exactly sure if this brass is "healthy" as it is more copper colored, than that new yellow color. Any info on what I did here? I plan on loading some and testing it out, I'm just scratching my head here. What it supposed to look like on left, what it did after 12 hour tumble with lemi-shine/soap on right. Link to comment Share on other sites More sharing options...
Solvability Posted September 2, 2012 Share Posted September 2, 2012 I think that was a galvanic reaction between dissimilar metals - NBD. Link to comment Share on other sites More sharing options...
BullyDog Posted September 2, 2012 Share Posted September 2, 2012 I had that happen several times, You can get the brass shine back in corn cob or walnut media. Link to comment Share on other sites More sharing options...
kevin c Posted September 2, 2012 Share Posted September 2, 2012 What they said. My understanding is that whatever solution you used leached a bit of the copper out of the surface of the cases and then redeposited it, but in a way that shows the copper color more. I've shot brass this way. Granted the loads are mostly at minor PF, and we're not talking about thousands or even hundreds of cases, but I haven't experienced any splits or failures. Link to comment Share on other sites More sharing options...
Jonathan Taliani Posted September 2, 2012 Share Posted September 2, 2012 I wouldn't sweat it. The lemi-shine causes that discoloration if left in too long. Link to comment Share on other sites More sharing options...
BulletBoy Posted September 2, 2012 Share Posted September 2, 2012 A timer is your friend Link to comment Share on other sites More sharing options...
spideysteve Posted September 10, 2012 Share Posted September 10, 2012 A timer is your friend You can use a timer, but it's still in there soaking ... I've found that Speer does this just about all the time, most other brands don't. Not sure what it is about Speer. I just load them and shoot anyways, haven't had an issue yet Link to comment Share on other sites More sharing options...
SPRSkip Posted October 6, 2012 Share Posted October 6, 2012 I have not done this yet but have come close. Good to know that it will shine back up. Hmm now where did I put that tumbler. Link to comment Share on other sites More sharing options...
MarkCO Posted October 6, 2012 Share Posted October 6, 2012 It is called "Dezincification". When the zinc content in brass exceeds about 15% (some say 20%) the zinc is prone to preferential corrosion. Cartidge brass is about 30% zinc. The light green/white residue on old brass is mostly zinc oxides. Plain tap water will cause dezincification in cartridge brass over enough time. This is also one of the reasons why I don't do wet tumbling of brass. The copper color tells you not only that the zinc has left the surface, but that most likely, the internal cracking has started. I do failure analysis for a living and have written literally hundreds of reports on this subject, so please ignore the people telling you it is fine, because they really are ignorant. So while I don't relish my Enos posts being read to me in depositions, this one is certainly worth it for your safety. If you want to mail me a few pieces, I will section it and put it on the scope and show you the fractures. Link to comment Share on other sites More sharing options...
noylj Posted October 7, 2012 Share Posted October 7, 2012 +1 with MarkCO Many people use vinegar. Vinegar is known to leach out zinc. What your leach out leaves voids behind. I haven't read whether citric acid will leach out zinc like some/all other acids. RCBS sells their ultrasonic case cleaner containing citric acid and ammonium hydroxide. The ammonium worries me, particularly if you soaked for a long time (vs. 10 minutes in the ultrasonic cleaner and a good rinse after) as ammonia is great for making brass brittle, but the acid and base should actually be giving a solution of ammonium citrate salt. One assumes RCBS knows what they are doing. Just think, all you need to do is wipe off the case exterior to remove any dirt/grit. Instead, people are spending a lot of time, energy, and money on making their brass all clean and shiny (and without the metallurgy to know if what they are doing is safe). Link to comment Share on other sites More sharing options...
latech15 Posted October 7, 2012 Share Posted October 7, 2012 I for one would like to see what Mark can come up with under a microscope. I have had brass do this before and I have used it, but, as it relates to this chemical reaction and what it may or may not do to the metal, I am certainly ignorant. Maybe Mark can help un-ignorant me . He certainly has done so with his shotgun loading products. Link to comment Share on other sites More sharing options...
jmorris Posted October 7, 2012 Share Posted October 7, 2012 I had a batch that ran too long as well. Little over 2000 9mm cases, loaded them up with minor loads and they all worked fine. Link to comment Share on other sites More sharing options...
HI5-O Posted October 7, 2012 Share Posted October 7, 2012 Last week at a electrical fire training class I spoke with one of the presenters who is a metallurgist (sp?) and he knew about cartridge brass (70% copper/30% zinc). He was telling me when the price of copper went up, he believes the amount of copper in cartridge brass went down (to save money). Typically cartridge brass is 70/30. Also, he told me he would not polish the brass and if I wanted shiny brass to use new brass. Link to comment Share on other sites More sharing options...
MarkCO Posted October 20, 2012 Share Posted October 20, 2012 I for one would like to see what Mark can come up with under a microscope. I have had brass do this before and I have used it, but, as it relates to this chemical reaction and what it may or may not do to the metal, I am certainly ignorant. Maybe Mark can help un-ignorant me . He certainly has done so with his shotgun loading products. I don't have a piece of brass coming from Kyle, but I just got hired on a new case where it looks like the brass failed due to dezincification. Will try to get a 400x photo up when I can. Link to comment Share on other sites More sharing options...
ncxdm Posted October 25, 2012 Share Posted October 25, 2012 Just wanted to say thanks MarkCO for the info. Useful stuff to have a little more scientific outlook on. Again thanks. Link to comment Share on other sites More sharing options...
Chills1994 Posted October 25, 2012 Share Posted October 25, 2012 Mass spectrometer... A before treatment sample, then test an after treatment sample to see how much zinc has been stripped from the cases??? Slight thread drift... For the boolit casters who accidentally melt in zinc wheelweights in with their lead wheelweights is there a way to get the zinc out? Link to comment Share on other sites More sharing options...
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