Why did my brass turn copper color?

[dearslayer]

I normally wet tumble around 200-400 rounds at a time in my FA tumbler using steel pins, Dawn dish soap, and Lemi shine. Last night I did as usual with some 9mm but I think I may have put too much Lemi shine in... more that usual. Once cleaned I usually lay out the casings on a perforated kind of pizza tray to dry in the oven for an hour with temp set at around 150-160. Problem is the brass came out this time looking like copper and not the usual shiny new looking brass that it normally does. Not that the look matters but I'm curious if maybe too much Lemi shine caused this??

 

[BattleRife]

Probably. I believe Lemishine has a considerable citric acid content. Acidic solutions tend to attack the zinc preferentially, leaving the copper behind. The effect is no more than a few atoms deep.

 

[Potashminer]

Not sure. Your cartridges are likely mostly made of copper alloy - varying amount of zinc and other things - so the "copper colour" that you describe might be "normal"? Why not just run through another shorter cycle with the steel pins , but get your additives correct - maybe the issue goes away? You do contradict yourself - "did as usual" versus "may have put too much Lemi shine in".

 

[Munkey1973]

Its strictly a cosmetic problem.

I too use an FA (large barrel) Stainless Steel and coincidentally I did two fresh batches tonight actually.
I use a scoop that came with my coffee machine that is exactly 13 milliliters (so just shy of 1 US tablespoon) .... anyways, I use one level scoop of Lemishine and then 2 level scoops of Dawn Ultra Lemon/Yellow and 4 litres of room temperature distilled water..... 2.5 hour cycle.

Perfect pale blonde brass every time. If I were to dry this brass in the oven on low, then it will most likely turn a bit orange. But unless I pressed for time, I always let my brass air dry for a couple days and It keeps this colour.

We have very hard water in Regina and my home does not have a softener. Before I purchased my 4 litre water distiller I'd get the occasional batche here and there where the brass was a very deep rose colour when I used tap water (especially if it was warm or hot).

At the end of the day, if you don't get the "colour hue" that you desired, then at least your brass is clean and you need to worry too much about carbon scratching up your dies and trimmer pilots.

 

[dearslayer]

Not sure. Your cartridges are likely mostly made of copper alloy - varying amount of zinc and other things - so the "copper colour" that you describe might be "normal"? Why not just run through another shorter cycle with the steel pins , but get your additives correct - maybe the issue goes away? You do contradict yourself - "did as usual" versus "may have put too much Lemi shine in".

Yes I guess did contradict myself didn't I. What I meant was I did everything as normal except I think I may have added a little too much Lemi shine. I normally add an empty 9mm case full but this time for some reason I just poured some in. Also as an after thought I do remember seeing an old steel case in the mix ( range pick up perhaps ) so would this steel case maybe have reacted with the Lemi shine to cause discoloration?

Also I did tumble again this afternoon with just some dawn and steel pins but I didn't take out that one steel case ( never thought about this at the time ) but it made no difference in the color.

 

[45C]

It’s not from to much Lemi- shine .
It’s from a case, made from a different metal.

 

[cosmic]

I use citric acid as part of my cleaning solution. It will change the color of the brass if left too long, or not neutralized after cleaning (I use baking soda)

 

[dearslayer]

It’s not from to much Lemi- shine .
It’s from a case, made from a different metal.

Yeah I had read somewhere online last night at work about how even one single steel case might have some reaction causing discoloration. Not sure if it's true, but I did find one steel case in the mix and didn't think much about it until I posted this thread. Question now is how to bring back that shiny brass blond shine if possible? It's just one of those stupid things that will bug me. Usually the brass I clean comes up like new. Well at the very least like others have stated at least it's clean.

 

[theDuck]

I've had this happen a few times. Too much Lemishine then the heat makes it more copper coloured. I know when I have put more Lemishine in than I normally do.I use about 220°F so I am above the boiling point. I've never had a steel or other metal case in the mix and it happens. I just reload and carry on.

 

[45C]

Yeah I had read somewhere online last night at work about how even one single steel case might have some reaction causing discoloration. Not sure if it's true, but I did find one steel case in the mix and didn't think much about it until I posted this thread. Question now is how to bring back that shiny brass blond shine if possible? It's just one of those stupid things that will bug me. Usually the brass I clean comes up like new. Well at the very least like others have stated at least it's clean.

You won’t get it back to the normal color, I’ve tried.

It’s not the lemi-shine. I’ve been using it since 2013 and I don’t measure the amount I use.
The copper discoloration has happened to my brass a couple of times,from mixing in steel cases.
You could probably reload it as is, I don’t, but I don’t see why you can’t.

It’s ugly but it’s still brass.. lol

 

[dearslayer]

I couldn't rest this morning until I tried something/anything so I soaked the batch in household vinegar. After about 10 minutes of swishing it around I noticed the shine coming back. I rinsed with lots of water including a bath with baking soda to neutralize it. I think the results are pretty good. The copper colour in the photo with the two steel cases isn't as noticable as in person but the end result after the vinegar soak is the usual blond color. I dried it in a towel to remove excess water and I'm gonna let it air dry this time ( no oven ) to see if it stays shiny.

 

[New Camper]

Probably. I believe Lemishine has a considerable citric acid content. Acidic solutions tend to attack the zinc preferentially, leaving the copper behind. The effect is no more than a few atoms deep.

^^ is my first suspicion. High concentration of certain acids which worsens the condition as exposure time increases. The chemical reaction removes zinc from the alloy of mostly copper that constitutes brass leaves the orange/red copper. I'm surprised OP didn't worsen the condition with the vinegar bath but provided it's only surface discoloration carry on reloading. You can also cook off the zinc by exceeding the temperature required to correctly anneal brass. This is thorough destruction and softens the neck to the point that the brass is no longer useful for loading.

You won’t get it back to the normal color, I’ve tried.

It’s not the lemi-shine. I’ve been using it since 2013 and I don’t measure the amount I use.
The copper discoloration has happened to my brass a couple of times,from mixing in steel cases.
You could probably reload it as is, I don’t, but I don’t see why you can’t.

It’s ugly but it’s still brass.. lol

I'd have never thought of this but it to makes sense. Beyond the destruction of galvanic corrosion, this doesn't cross my path often. I often use an ultrasonic cleaner in the soap and 50/50 water/vinegar solution and have never had an issue either. Though I thoroughly rinse the brass with hot water to neutralize and conclude the cleaning process. Otherwise dirty brass gets the tumbler walnut shell with polish for a couple hours.

 

[uglydukwling]

I've never experienced it with brass cases, but it's a common problem with brass screws, especially immersed in sea water. The zinc goes into solution (a process known as dezincification), leaving what looks like a copper screw, but with much of the metal gone, the spongy copper has negligible strength.

 

[bertn]

Exactly, the acid dissolved some of the zinc out of the alloy, leaving the copper behind.

This is irreversible so the pink stains stay but you can still use the cases.

OP, did you use cold or warm/hot water?
Hot water makes the acid way stronger and in my experience does not help much in cleaning so stick with cold water for tumbling.
And do not leave brass in your tumbler once it is done, I had pink sports once leaving it in overnight.

 

[dearslayer]

Exactly, the acid dissolved some of the zinc out of the alloy, leaving the copper behind.

This is irreversible so the pink stains stay but you can still use the cases.

OP, did you use cold or warm/hot water?
Hot water makes the acid way stronger and in my experience does not help much in cleaning so stick with cold water for tumbling.
And do not leave brass in your tumbler once it is done, I had pink sports once leaving it in overnight.

if I remember correctly I used warm-hot water. Ill use cold water next time for sure to see if it makes a difference.

 

[45C]

I tumbled a couple of hundred cases last night, hot water, dawn,and lemi-shine.
I just guess the amount of lemi-shine.

They’ve been soaking in the mixture for almost 24 hrs now, I’m sure I can leave it for a few days and it’ll be shiny as new.

 

[dearslayer]

I tumbled a couple of hundred cases last night, hot water, dawn,and lemi-shine.
I just guess the amount of lemi-shine.

They’ve been soaking in the mixture for almost 24 hrs now, I’m sure I can leave it for a few days and it’ll be shiny as new.

I'm thinking it had to do with the couple steel cases that were mixed in. I originally thought it was only one but checked the batch this morning and it was two cases. i've never had this issue before.

 

[45C]

I'm thinking it had to do with the couple steel cases that were mixed in. I originally thought it was only one but checked the batch this morning and it was two cases. i've never had this issue before.

I’ve had it happen a couple of times, a combination of range brass and doing large amounts and shat happens.. lol

 

[bertn]

I'm thinking it had to do with the couple steel cases that were mixed in. I originally thought it was only one but checked the batch this morning and it was two cases. i've never had this issue before.

I doubt it had to do with the steel cases.
For sure the warm/hot water did it.

A little side track story about hot and acid, I once wanted to remove calcium deposits from a shower valve and thought
that using toilet bowl cleaner with some muriatic acid in it would be a good idea.

This was not a build in valve by the way. I used the shower right before to wash down the walls etc. so it was still hot.
I started brushing the cleaner on the cold side of the valve and it worked great, the calcium dissolved so I then brushed the whole valve.
Came back a few minutes later and on the hot side of the shower faucet the chrome plating was almost completely gone, seriously!
The cold side was perfectly clean and chrome still on.
Wife wasn't really happy with the two-tone version lol.

 

[Blastattack]

For my Two Gallon setup (10lbs of media and 6lbs of brass) I use one .500 S&W case (~4ml) of pure citric acid, and hot water. I’ve never had any issues with discoloration. I also rinse the cases off in hot water and then bake them at 250F for 30 mins. Clean, shiny and perfectly dry every time.