Why did my brass turn copper color?

[Potashminer]

I did 188 x 22-250 Win brass - de-primed first - since this post started - in Frankford Arsenal tumbler - cool water, 1/4 teaspoon Lemishine (measured) and squirt of Dawn (not measured) with 5 pounds of stainless steel pins that came with the tumbler - I have never weighed them - some suds left after 2 1/2 hours tumbling - no discolouration - look to be shiny clean inside and outside, although still some black marks showing in primer pockets where factory primers had fired - good enough. Water added was hot & cold mixed - all comes through water softener first - rinse was garden hose which is raw well water - known to have high (400+) minerals. Air dried standing case mouth down in bread pan with three layers window mesh on bottom.

 

[Bubba Yugga]

I've used generous amounts of lemishine without any issue.
The strength of the electrolyte is immaterial if you don't have any dissimilar metals.
It's the introduction of the other cases that got the battery effect going.
One is the cathode, the other the anode.
Boom, you're stripping the zinc off the brass and plating it onto the steel.

 

[Chatrbaz84]

Instead of cleaning liquid put half of lime in it for 1.5 hrs

 

[BattleRife]

The strength of the electrolyte is immaterial if you don't have any dissimilar metals...
Boom, you're stripping the zinc off the brass and plating it onto the steel.

This is not correct.

Firstly, there are other corrosion mechanisms apart from galvanic corrosion. In fact most corrosion involves other mechanisms, including the common rusting of steel.
What is going on in this instance is dissolution of zinc at the anode, and the combination of oxygen and hydrogen ions at the cathode to form water. This is a very powerful reaction and the reason acids combined with oxygen are so destructive to metals.

Secondly, spontaneous plating of zinc onto steel would be a pretty strange circumstance. To get zinc out of solution requires an applied voltage, there is no such thing as electroless zinc plating.

 

[dearslayer]

Well I did about 500 rounds of 9mm last night and used room temperature water ( tried distilled this time ) with a shot of Dawn and an empty .40 S&W case of Lemi shine. Tumbled for 2 hours and towel dried and left out in the basement to finish drying ( no oven this time ) and they came out pretty shiny. No copper color. Will do the same tonight with another 600 round batch but will use tap water even though its on a water softener to see if there is any difference. Attached photos show the dirty cases in the bag and other photos cleaned.

 

[mbogo3]

Undeniable proof of global warming.

 

[Helka]

I had a batch of brass come out pink. i apparently put to much lemon shine in.

 

[laurencen]

to date never used the tumbler to clean brass instead ultrasonic but brass is always dull, picked up tumbler and going to try it this weekend, you deprime the brass do you also size it prior to cleaning?

 

[stewbud]

to date never used the tumbler to clean brass instead ultrasonic but brass is always dull, picked up tumbler and going to try it this weekend, you deprime the brass do you also size it prior to cleaning?

No, the purpose of decap prior to cleaning is to get the primer pockets clean and to keep your dies clean, also.

 

[Helka]

for bigger calibers i deprime then tumble then size. for small calibers i leave the primer in because i'm lazing and don't want to deprime 1k 9mm at a time to make tumbling worth it lol.

 

[dearslayer]

I usually deprime whatever I shot, the same day, so I don't end up having to do 1000 at a time. Given the fact that my last 2 batches came out looking great, I'm convinced the steel/aluminum cases mixed in the previous batch was the reason the cases came out copper colour. Or perhaps it was the combination of steel cases and oven dried. Either way I'll keep doing it this way.

Edit: distilled water used in the 2nd last batch, and tap water used in the last batch ....same shiny result.

 

[Potashminer]

to date never used the tumbler to clean brass instead ultrasonic but brass is always dull, picked up tumbler and going to try it this weekend, you deprime the brass do you also size it prior to cleaning?

I have read that tumbling will beat hell out of case mouths, etc - so I de-prime, then wet tumble in stainless pins - dry, etc., then lube and size, then trim to length, chamfer and de-lube in one step with case in the Lee spinner. Never thought much more of it - just the way I do it - say 100 to 200 round batches of centerfire rifle. I have never reloaded pistol rounds... If I have previously processed the brass and measure say one out of 5 or 10 to be less than maximum case length, I just omit all the brass cleaning and go directly to lube for re-sizing / de-priming.

I have fired hundreds, maybe thousands, of centerfire rifle rounds that are not "shiny" - might make a difference for some, but made not difference for me - clean matters, "shiny", I think, is for the "eyes only"...