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Old August 7, 2018, 08:36 AM   #1
mgulino
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Pink brass

Just curious if anyone else has experienced this.
I use a Harbor Freight wet tumbler with SS pins (blue dish washing liquid, lemi shine, and water solution) to clean brass. Sorting some 9mm cases recently, I mistakenly included a steel case with one batch of my brass cases. After tumbling for about an hour, that batch of brass came out a pretty pinkish-copper color. All else seems normal, so I may just keep those cases for my daughter.
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Old August 7, 2018, 09:34 AM   #2
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Pink Brass: Many years ago I started cleaning brass; some of my methods had an effect on the color of brass and a few methods caused the brass to disappear. There was one method that turned brass orange and or pink, after a few days the brass started disappearing. SO? I changed my methods and techniques, I started cleaning brass with a time limit. I started cleaning brass in 5% vinegar for a maximum of 15 minutes for the life of the case. I found vinegar was only necessary for the very worst of cases and it was not necessary to repeat the process over and over and over etc.

Today? Reloaders insist on using some type of acid over and over.

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Old August 7, 2018, 10:45 AM   #3
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Sounds like the zinc has been etched from the surface of the brass leaving only copper exposed.
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Old August 7, 2018, 11:25 AM   #4
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What you are seeing is cuprous oxide which is a brass oxide that has a reddish color. Shoot them as is or if you want them yellow again use corn cob media or a non ammonia polish

your brass has not been harmed in any way

Quote:
cuprous oxide is the inorganic compound with the formula Cu₂O. It is one of the principal oxides of copper, the other being CuO or cupric oxide. This red-coloured solid is a component of some antifouling paints.

Copper(I) oxide may be produced by several methods.[3] Most straightforwardly, it arises via the oxidation of copper metal:

4 Cu + O₂ → 2 Cu₂O
Additives such as water and acids affect the rate of this process as well as the further oxidation to copper(II) oxides.
https://en.wikipedia.org/wiki/Copper(I)_oxide
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Old August 9, 2018, 07:14 AM   #5
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and here I thought this was going to be a fashion ammo thread - so happy it's not ;-)

Thanks for the details Hounddawg
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Old August 10, 2018, 09:50 AM   #6
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I soak my brass in Lemishine, usually for an hour, prior to tumbling. I left the brass in over night one time and it had a pink coloring to it. A strong amount of Lemishine might do the same thing.
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Old August 10, 2018, 05:50 PM   #7
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I have had this happen when a steel case is in the mix with ultrasonic cleaner. something to do with a mild acid and mix of steel and brass? some came out pink and some normal. Even did it to a die once. Same thing, steel part in ultrasonic with dirty brass cleaner. It came out a tie-dye steel-brass-black color. Wont do that again!

Edit- Didn't hurt the brass or die as far as I could tell. All the brass tumbled clean (yellow) with walnut eventually, not so much for the die, still worked fine. Eventually replaced the die, OCD or ADD made me do it.

Come to think of it the wife might like pink ammo to go with the pink grips on her 9mm, top it off with a red powder coated bullet... might make a fashion statement. Might be on to some good marketing tool... Sorry grey lion, couldn't help my self.
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Old August 10, 2018, 07:27 PM   #8
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when you mix dissimilar metals with a acid it makes a battery and this thing called galvanic corrosion.

The main cause of the pink patina is too much acid. This is one of those things where more is not necessarily better. A little is all that is needed. I use 1/4 tsp of acid (white vinegar, lemishine, bottled lemon juice) and 1/2 tsp of detergent in my tumbler, for 1 hour. That is plenty to do the job
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Old August 11, 2018, 01:20 AM   #9
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Quote:
mgulino wrote:
...(blue dish washing liquid, lemi shine, and water solution)... a pretty pinkish-copper color.
The steel case is an anomaly here.

Expose brass to to a weak acid (and citric acid, which is Lemishine's active ingredient, is a weak acid) for too high a concentration or too long a time and you will liberate some zinc from the surface of the brass and it will turn pink.

The amount of zinc liberated will generally not affect the mechanical properties of the brass since it only occurs on the surface atoms. You can try re-tumbling the brass with just a pinch of Lemishine and see if that restores the shine to the brass.
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Old August 11, 2018, 05:58 AM   #10
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No steel is needed and too much acid with no steel at all will cause a pink hue just as you can get galvanic corrosion with no acid at all. Bottom line is a little acid is all that is needed when wet cleaning and don't mix dissimilar metals with a electrolyte

If you don't believe that take a old case and drop it in vinegar or lemon juice for a few hours, you don't have to take my word for it
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Old August 15, 2018, 08:28 PM   #11
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Thanks for all the advice. Guess I'll be more careful when sorting steel from brass and measuring my LemiShine.
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Old August 15, 2018, 10:07 PM   #12
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LemiShine's only use is to soften the water, which makes the detergent more effective.
Depending on the hardness of the water in your area, there might be no need for lemishine at all.
Try to tumble without lemishine and check the result.
Add lemishine as needed or extend your tumbling time (whatever fit your needs).
I had it happen in my area, that I had to use a high amount of lemishine in the beginning.
After a year being here, all of a sudden my brass turned pinkish after tumbling.
Now I don't need lemishine at all anymore.
The slightest amount of it will turn my brass pink.
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Old August 15, 2018, 10:44 PM   #13
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Simple:

Too much Lemishine. I only use a .45ACP case full for a large batch in my Thumblers Tumbler. Your tumbler is a lot smaller.......use half what I do and it should be fine. I doubt the steel case had much to do with it.

Lemishine is citric acid.....a little will clean brass......a lot will change it's chemistry. I have my doubts about it making Dawn more efficient. IMO, Dawn is the detergent that cleans the crud away, while the citric acid removes the stains that detergent won't touch. Together with s.s. pins they make ...... bling!

Last edited by GWS; August 15, 2018 at 11:02 PM.
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Old August 15, 2018, 10:46 PM   #14
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Got some new never-chambered 300 Savage Red in color Herters brass here. Can't say I've ever seen pink brass. If I where to discover some pink? I'll remove it as quickly as I can and bury in the back yard so's not infect my yellows.
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Old August 16, 2018, 06:20 AM   #15
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MarcoB and GWS, Since my tumbler has two containers, I will try one batch with LS and one without. The batch with LS will get a .380 case full to start.

I did dry tumble the pink brass and it came out all shiny and yellow.
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Old August 16, 2018, 08:29 AM   #16
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It is called Dezincification. When you see the pink to reddish color, the brass has had the zinc removed and is substantially weakened. I have written about it several times to inform. It is a significant problem and I have worked professionally on several cases where brass failed due to dezincification.

Yes, the presence of Iron Ions accelerates the process, as does pH being off (too much LemiShine). Heat, agitation, pH too low and some other metal Ions will all accelerate the dezincification process. The manufacturers use buffers to mitigate the issue.
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Old August 16, 2018, 10:59 AM   #17
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Quote:
It is called Dezincification. When you see the pink to reddish color, the brass has had the zinc removed and is substantially weakened.
Before the Internet I cleaned the worst of cases in vinegar; I settled on the 5% type simply because it was cheap and like Tootsie-Roll, it last a long time. I set a time limit of 15 minutes, I could have reduced the time by stirring; after soaking for 15 minutes I rinsed twice in boiling water. The process reduced tumbling by days, The 15 minutes in the vinegar reduced tumbling time to maximum of 2 hours. I understand that is not impressive but when I start on 1,400 cases from one batch and 2,600 from another batch time is reduced from months to days.

Before that I used a more time saving acid; case time in the acid (ctita) was reduced to about one minute. The advantage to the 'other acid' was realized when cleaning cast iron tools, post and pans etc. When using it for a cleaner it took on the appearance of a Frankenstein movie.

Anyhow, when using acid be prepared to push yourself away from the computer keyboard because you do not want to leave a residue on the case.

F. Guffey

Last edited by F. Guffey; August 16, 2018 at 11:01 AM. Reason: remove 3
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Old August 17, 2018, 12:37 PM   #18
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I also wet tumble , in the beginning I also would get some pinkish cases , I stopped using the LemiShine now my brass looks like brand new inside and out . Asked my wife why she didn't use Dawn she said Sun Dish Detergent works better , she was right .
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Old August 17, 2018, 02:32 PM   #19
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The OP wrote:
Quote:
Thanks for all the advice. Guess I'll be more careful when sorting steel from brass and measuring my LemiShine.
A strong magnet will find the steel cases very fast. Check Ebay or Amazon.
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Old August 17, 2018, 03:35 PM   #20
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Quote:
Originally Posted by MarcoB
LemiShine's only use is to soften the water, which makes the detergent more effective.
Depending on the hardness of the water in your area, there might be no need for lemishine at all.
No, it's more than that. 5% citric acid was the old Frankford Arsenal brass cleaning formula before the military stopped removing forming process oxides from their cases. It actually reacts with oxides to reduce them. I have a fuzzy video I can't seem to find of me sticking a 30-06 case covered with verdigris into a warm (140°F) beaker of that solution for less than 15 seconds and the verdigris was completely gone, leaving only black oxides behind. Citric acid also passivates the brass surface, making it hard for fresh oxidation to begin again. It is used as a treatment by brass foundries to prepare cast brass parts for long-term storage. It does soften water by reacting with the alkaline minerals in it to chelate them, but the solution then remains acidic. The real question is, since Frankford Arsenal didn't add soap to citric acid for case cleaning, is doing that the actual waste of time? I don't think so, as the detergent appears to keep dirt and carbon particles in suspension, but I have not done an extensive experiment to see if those wouldn't just rinse out without the soap being used. I should do that.

This has been discussed in great detail at the Cast Boolits forum; 42 pages worth.
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Old August 18, 2018, 10:10 AM   #21
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Quote:
No, it's more than that. 5% citric acid was the old Frankford Arsenal brass cleaning formula before the military stopped removing forming process oxides from their cases.
I would have to go dig for the formula, I do not believe it would be worth the effort but the formula used long before the Internet was referred to as pickling, I have no ideal what would happen if I asked a pharmacist to but the ingredients together.

Time is a factor.

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Old August 18, 2018, 10:28 AM   #22
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Pickling is still done with sulfuric acid as a prep for nickel plating. Citric acid doesn't seem to react with cuprous (red) copper oxide as sulfuric and nitric acid will, and it takes some more time on cupric (black) copper oxide than it does on verdigris (copper carbonate here, but also copper chloride near salt water). So the pinkish hue left after using citric acid to clean a heavily tarnished case has to be polished off if you want it removed. You can see it in the post-cleaning photo below.

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Old August 18, 2018, 12:45 PM   #23
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The black cases I was referring to had to do with the finish product, had to do with what I call the worst of cases.

Orang/pink etc. It is a given when cleaning cases in vinegar. I have a limit if 15 minutes, I could reduce the time by stirring the cases but when I started I tested a a few cases. I started by leaving the cases in vinegar for 2 days, the cases started to disappear; I cut the time back to 30 minutes and found the cases turned orange/pink etc., it was about that time I settled on 15 minutes, and I rinsed the cases in boiling water it seems there are some chemicals that have an affinity to some metals and boiling the cases to rinse cut down on tumbling time.

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