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Old February 11, 2013, 08:16 AM   #1
Magnum Wheel Man
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Pink brass... the weaker sex ???

nope nothing to do with lady shooters...

I reciently started wet tumbling with stainless pins, using a drop of dish soap, & a couple scoops of citric acid... does an awesome job cleaning up the brass... however, if I have one of the dark brown / black cases, those clean & polish to a pinkish cast... on another thread, I think it was mentioned that was some sort of reaction with the copper that turned them dark when left in the elements...

... I'm wondering if these might be weaker than the other non pink cases, perhaps more prone to cracking??? anyone have any experience with them ???
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Old February 11, 2013, 09:38 AM   #2
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I think you might be overdoing the citric acid and skimping on the soap, ending up with an overly-acidic solution.

I know that the "recipe" that STM recommends for their stainless-pin wet tumbling is 1-2 tablespoons of dish soap, and only 1/4-teaspoon of Lemishine (citric acid).
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Old February 11, 2013, 09:52 AM   #3
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the mix I'm using, works well ( I still have suds after 3 hours of tumbling... which my understanding, is you should use as little soap as needed to still have suds at the end of the tumbling process )

my scoops are pretty little ( I'm using like a 1 cc Lee powder dipper )

the pink is the result of starting with the black / brown case, not from my solution
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Old February 11, 2013, 10:08 AM   #4
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The pink cases have lost some of the alloying zinc in the brass and are indeed weaker.

Zinc is sacrificial to just about everything in galvanic corrosion. Pretty easy to imagine losing zinc in a case laying about on the ground.
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Old February 11, 2013, 10:19 AM   #5
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Some zinc has been removed, leaving the copper behind. I currently load the pink stuff along with the other and haven't had a problem to date with pistol rounds.

Wondering if someone out there has experienced premature failure of pink brass?
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Old February 11, 2013, 10:26 AM   #6
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Dish soap forms a basic solution in water, and citric acid forms an acidic solution (obviously). By skimping on the soap and overloading on the citric acid, you're pretty much relying solely on the acid to do the cleaning, which isn't the purpose of the citric acid.

The citric acid is just to provide a nice extra shine on the tumbled brass - realistically, you could leave it out entirely and the dish soap would handle the cleaning aspect of the tumbling all by itself (assuming you used the correct amount).

A pinkish cast on brass from lost zinc isn't uncommon when you're using overly-acidic cleaners. You'll see the same thing when you use acidic quickie-cleaners like "Tarn-X" on household brass, instead of ammonia-based cleaners (which are basic, not acidic).

Try one batch with a lot more soap and a lot less acid, and see if it doesn't treat your range-darkened brass more kindly. Go ahead and give the STM recipe a try. Just for reference, the recommended 1/4 teaspoon of citric acid would be about one-fifth of a dipper full, if you're using the Lee 1cc dipper.
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Old February 11, 2013, 10:41 AM   #7
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I may be strong on the citric, but 3-4 drops of soap can leave me with with too much foam... I'm sure that amount varrys by the concentration level of the soap...

heard the Simple Green types of soap work well... btw... I don't necessarily use a whole lot of water... maybe a quart or so in my RCBS Sidewinder, with 2.5 lbs of pins, & 200-250 pistol cases

however, the cleaning concentration is not going to effect what has already happened to the case while in "the elements" if the case is black, it's already had some galvanic corrosion... perhaps using enough citric to cause them the pinkish cast, will allow them to be better identified if they fail before the others in the batch ???
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Old February 11, 2013, 10:48 AM   #8
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The black cases have come in contact with ammonia that forms in nature. This make brass brittle & unsafe. Google "stress corrosion cracking" or "Season Cracking"
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Old February 11, 2013, 10:58 AM   #9
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I'm more concerned about what the citric acid is doing to the rest of your cases, not just the range-darkened ones. Also, just because the corrosion process started when the case was on the ground, that doesn't mean that you can't make it worse by using an acid concentration 20-40 times higher than what it needs to be.

Essentially, you've taken what's meant to be an optional "sparkle additive" (the citric acid), and you're using it as the sole chemical cleaning agent in your process (one drop of dish soap in a quart of water isn't doing anything significant).

It's your brass, do what you want, obviously. But if you want to know why you're getting a pink cast on tarnished brass, it's because you're acid-raping the hell out of it. I've seen plenty of darkened range brass that polished up just fine in a wet tumbler with stainless media, and didn't turn pink.

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Old February 11, 2013, 11:06 AM   #10
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well... ok... if I'm "raping my brass", I can cut back on the citric some...

BTW... I did work my way up to a couple cc's of crystalized citric ( it is powdered, not liquid ) & a couple seems to clean better than a single scoop, & I did work my way down on the soap, my mixture seems alot easier to rinse than with a more soap ( my understanding, is you want only enough of the surfactorants in the soap to keep the "dirt" from redepositing on the brass )

however if those that are saying the cases are brittle when black ( even before they turn pink ) maybe those should be disposed of, rather than polished in the 1st place... yet there are people like SUFR, that have loaded them, with no bad results, even when pink... I'd be curious if those cases had been loaded a couple times with no issues ???
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Old February 11, 2013, 11:23 AM   #11
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Quote:
BTW... I did work my way up to a couple cc's of crystalized citric ( it is powdered, not liquid ) & a couple seems to clean better than a single scoop
The citric acid isn't supposed to be the main cleaning agent. I'm not surprised you're having to use so much of it to get the cases clean, especially if you're reducing the amount of dish soap at the same time.

Any kind of tarnish means that you've lost at least *some* of the metal - the black residue on your cloth after you polish silver is just an oxide of silver, for example. That doesn't mean that you've removed enough of the material to matter - it might just be a micron or two that have been removed from the surface.

But do a search for "Tarn-X" and "pink brass" and look at the results, keeping in mind that Tarn-X is nothing more than a citric acid solution with a little bit of fine clay for abrasiveness. I think the acid-based cleaners may remove a disproportionate amount of zinc, leaving behind the pink copper.

Basically, if your brass is tarnished at all before you polish it up, you've lost some metal, by definition. That doesn't mean that the brass is unsafe to use. But I also don't think that you're doing your brass any favors by cleaning them in a strong acid solution. Let the stainless pins do the work, add in an appropriate amount of soap to make a slightly caustic (not acidic) solution to help the pins along, and then a dash of citric acid for sparkle.
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Old February 11, 2013, 11:45 AM   #12
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Then there is "Dezincification "
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Old February 11, 2013, 04:36 PM   #13
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It is another situation where reloaders turn their head or ignore the problem in the big inning, before the Internet, reloaders, before the Internet knew when they used an acid for cleaning cases the cases turned pink and or orange, In the old days, in the big inning reloaders were better readers, they had an ability to read and comprehend, they were also good listners.

Me? I clean my cases in a tumbler with corn ground up cobs and NOTHING! In the beginning of the Internet cases turned orange when cleaned in an acid like vinegar. reloaders left their cases in the acid tooo long, Before the Internet reloaders followed instruction, when they used acid to clean their cases they rinsed their cases with boiling water, not once but twice.

Then came stainless pins, and I ask why stainless pins? Could it be because stainless steel pons resist rusting when exposed to an acid? Back to ‘WHAT HAPPENED?” In the big inning acid turned cases orange and or pink when exposed to acid, reloaders have gone back to using an acid with stainless pins, same cases. the story all ways starts with “Here is what I (big ‘I’) do.... .

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Old February 11, 2013, 04:52 PM   #14
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hmmm.... my cases are all a nice golden yellow color, except for the ones that started out black / dark brown, & those are golden yellow, with a pinkish cast...

key here, if I'm using acid / too much acid, am I really shortening my case life ??? or am I just not using corn cobs ???
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Old February 11, 2013, 05:27 PM   #15
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ScottRiqui,

Your concerns are misplaced. 5% citric acid (7 ounces added to a gallon of water; a lot more than Magnum Wheel Man is using) is an old Frankford Arsenal case cleaning formula from before the military found cases with oxides left on them had better corrosion resistance than cleaned and polished ones do. The reaction of the citric acid with brass tends to be self-limiting for practical purposes. That is, it reacts far, far more vigorously with oxides than with metallic brass. You can leave a case in it a very long time before thinning it to any significant degree.

Citric acid is also is used as a water softener, as it helps tie up minerals in hard water. That further improves cleaning properties of the water.

Dishwashing liquids and detergents that are labeled "mild" are not alkaline like soaps because they are not dissolved fats the require hydroxide ions to make them soluble in water. They tend to be somewhat alkaline as manufactured, but often the pH is brought down to make them easier on the hands. For example, in baby shampoo and conditioning shampoos, because being alkaline would dissolve or damage the oils they put in to condition the hair, the pH needs to come down to 7 or even go slightly acid. How, you may ask, do they bring the pH down? They add citric acid, as it not only adjusts the pH down, but it also is a preservative antioxidant for the oils. Yet the shampoos still clean.

Below are case cleaned in an ultrasonic for half an hour in a 140°F 5% solution of citric acid with Dawn PE mixed in. The oxides were gone in the first minute. The carbon took longer. Measurements of the necks with a tubing micrometer show now measurable loss of thickness. The head stamp is sharp and internal flash hole drilling burrs were still intact (unfortunately), indicating very little metal removal.

Though the cases in the bottom picture are not in the same order they were at the top, you can still see that it is the oxidized location that are left pink, as the zinc bore the brunt of the reaction with oxygen.

Before:


After:


All of these cases proved to be usable, by the way. The worst corrosion pits were only a couple thousandths deep, so no more than 10% of wall thickness on the thinnest part of the sides.
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Old February 11, 2013, 05:50 PM   #16
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It's not really a "concern", per se - like I said earlier, I don't think that the amount of metal lost when you remove tarnish/corrosion is significant enough to cause concern.

I just don't think that his solution (one drop of soap and 1/2 - 2/3 teaspoons of citric acid in a quart of water) makes much sense when wet tumbling with stainless pins. If you're just going to soak the brass in a bucket, or use an ultrasonic cleaner, then that's a different story, and more acid/less soap makes sense.

But if you're tumbling with stainless pins, I think it makes more sense to let the mechanical action of the pins do the work, rather than relying on the acid solution.

It's the same thing when I'm polishing brass around the house. If I wanted something that I could just "dip and rinse", I'd use something acidic like Tarn-X. The part will quickly come out clean, but I know that I'm going to end up with slightly pink, somewhat dull brass, like the cases in your second picture. But if I know that there's going to be mechanical action involved as well (like applying the polish with a cloth and then buffing it off), I'd use something less acidic, because I get better results.
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Old February 11, 2013, 09:08 PM   #17
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I simply MUST get off my lazy duff and remember to take some pH paper home the next weekend I'm doing a big tumbling run with my tiny 3# A-R1 Thumler. I'm using a small amount of Great Value dish soap and 3 or 4 pinches of Lemishine with enough water to cover 150 pieces of 9mm and about 18 oz of pins. Run for 1.5 hours. I need to get some before and after pH readings of what is working, then vary the chemicals and check results.

Aside from the terrific discussion posted above, I return to my prior question:
Quote:
Wondering if someone out there has experienced premature failure of pink brass?
Would the answer to this question not answer whether the pink brass is a concern? Is the pink discoloration just a surface issue or is it an indicator of a much more serious problem in the realm of the aforementioned bugbear of stress corrosion cracking?

(About a year ago, I saw some good samples of what appeared to be stress corrosion. Guy brought out a rebuilt German MG 34(?). All he had for testing was some old, old, did I mention OLD, South American import Mauser rounds. He kept having problems in full auto because the old cases were splitting apart.)
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Old February 12, 2013, 06:50 AM   #18
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Quote:
Wondering if someone out there has experienced premature failure of pink brass?
my question in my 1st post...

Quote:
I'm wondering if these might be weaker than the other non pink cases, perhaps more prone to cracking??? anyone have any experience with them
with the fact I'm happy with how my brass is looking now ( looks like new ), I'm fine with my cleaning solution... maybe the citric is harder to get / more costly for some, but I get samples of food grade granular citric acid all the time from work, as it's one of the ingredients I use at work, so the citric cost is not an issue for me, as it's in fact cheaper than the soap ......
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Old February 12, 2013, 09:43 AM   #19
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walmart carries it in the canning section for 2.97 a jar about the size of a large spice container. powder form
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Old February 12, 2013, 09:52 AM   #20
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Serf 'rett,

The brass in that photo had been in a bag during a basement flood at my dad's place. To check for damage, after the ultrasonic cleaning I subsequently polished it in treated corncob and all the pink turned into polished brass. So the pink wasn't deep enough to cause weakness.


Scott,

I see your point. I keep looking at pins and I own a Thumbler B, but haven't tried them myself as I am looking to get away from polishing rifle cases altogether at this point. I've seen several experiments and have done an initial one of my own that seem to indicate necks polished on the inside produce less consistent bullet pull and therefore greater MV spread than dull ones. So I have been running my polished necks over a turning case neck brush to roughen the inside lightly and have been leaving the chemically cleaned ones alone. That seems to be working out thus far, but I haven't determined which is best. The interesting thing to look at will be how the loads perform as they age.

Another element to all this is oxidation. Long ago (1920's, I think) Hatcher placed polished and unpolished cases on the roof of the Frankford Arsenal building which was in a location that had fumes from chemical plants and other industries in the air in those pre-EPA days. After a year on the roof, the polished cases had corroded through, while the unpolished ones were OK. So surface oxides offer some protection to the brass which can affect long term storage life.

I find that if you clean brass with vinegar and rinse it and leave them out, you will get fairly heavy surface oxide over time, with purples and greens. It might be good protection, but it's also good camouflage in the grass, so those cases are easy to lose in grass. The citric acid cleaned cases stay yellow. It gradually darkens, but is unmistakably brass, so the surface isn't activated the way vinegar affects it. I assume this oxide also has good corrosion resistance (untested), but it doesn't get lost in the grass. Indeed, I find it easier to spot the dull yellow than polished yellow because it doesn't mirror the grass. (Nickel-plated brass is the pits from this standpoint. It is practically invisible in grass as the mirroring doesn't alter the grass color.)


If someone using pins can run some cases with just soap and some others with the citric acid (or Lemishine or lemon juice as the source) added and set them up side by side for a month or two and report any difference in appearance, I would be interested to hear of it.

Experiments with greater or lesser amounts of citric acid would be interesting to hear of, too. You may have noticed that primer residue will fizz in acid, so there seem to be carbonates or other alkaline substances in it. For that reason it may be that primer pockets don't clean as easily in basic solutions as they do in acidic solutions, so that's another reason for the acid quantity to be experimented with.

Also, if anyone polishing their cases heavily and chronographing their loads would like to add to the shooting world's general body of knowledge, please also try experimenting with an inside neck brush and compare the results to loading cases polished on the inside of the neck to see what you get by way of velocity consistency differences. Of particular interest is how ammo shoots that's been sitting loaded for a year or so, brushed vs. not brushed. If the discrepancy worsens over time or goes away over time, it would be worthwhile knowing. I am aware ammunition is not wine and that aging it isn't be a normal practice, but if you load progressively for a season or two's matches all in advance, or load in advance for storage for the next mass extinction event or other survival scenarios, it would be good to know how your loading method's product ages in your storage conditions.


Magnum Wheel Man,

Citric acid in 10 lb quantity can be had for about $27 postpaid, here. I bought mine from him and service was prompt. That's enough for about 23 gallons of the 5% arsenal solution, which is already reusable for a long time. Probably a lifetime supply. Enough to make a group buy with friends worthwhile.
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Old February 12, 2013, 10:15 AM   #21
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so I get my citric for free... but posting availability & prices may help others...

I'm the type that likes to test out things like NICK outlined, however... it's cold & snowy right now, & I shot my old Chrony last year testing velocities of handloads out of a top break snubbie in 38 S&W... so I have to buy a new one by summer anyway, before I could do any testing...
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Old February 12, 2013, 01:21 PM   #22
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Unlike metals, bullets and cases? Bullets and cases are dissimilar, to have current flow dissimilar metals are necessary with an acid, dissimilar metals are necessary to make a battery, then, again, there is acid, acid is necessary to create current flow to make a battery.

Back to “BEFORE THE INTERNET” acid was used to clean cases, straight off, the instructions made it clear, 2 factors applied. One was percentage of acid, second was time, They had it down to 2% acid for a maximum of 3 minutes. Then they made it very clear, the cases must be rinsed in boiling water twice, between rinsing the water was to be changed. Effect on the case? The cases turned black, they referred to the process as ‘pickling’ as in for long term storage. Instructions from the mid 50s.

“Here is what I do” ect., I use corn ground up cobs and nothing, Tumbling with water anything, dry the cases? The anything used with water is still there, the anything does not evaporate, then there is that part about some acids, some find their own water.

Back to the worst of cases, I use vinegar, 5% maximum, I could use less by adding water to dilute, I use vinegar for a maximum of 15 minutes for the life of the case. I only use vinegar to reduce tumbling, cases that would require 4 days of tumbling can be cleaned in 15 minutes or less, cases cleaned in vinegar can be tumbled for 2 hours maximum to clean. Again, I rinse the cases, rinsing the cases does not guarantee I removed the acid, I do not recommend loading cases cleaned with vinegar, boxing them up for long time storage because of moisture and dissimilar metals, clean the cases and then shoot them, again, I am the only reloader without a guarantee I do not have dissimilar metals connected at the neck with an acid.

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Old February 13, 2013, 12:51 AM   #23
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Unclenick, I found your statement interesting :

Quote:
To check for damage, after the ultrasonic cleaning I subsequently polished it in treated corncob and all the pink turned into polished brass.
Some of my brass is pink going into the tumbler and pink coming out. The sst pins and Lemishine just make the brass clean and shiny, but no change in color.
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Old February 13, 2013, 02:10 PM   #24
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Serf 'rett,

The pink on yours may be deeper zinc loss, then. Basically, the polish took all my pink off, which is how I know it wasn't deep (polish doesn't remove much metal). This was corncob with Lyman's green polish added and run in an old Lyman Turbo-tumbler. I'm also wondering if it's possible for the stainless pins to burnish the pink copper up against the surface rather than removing it. I wouldn't expect so, given how well it takes carbon off, but then the carbon is more brittle.

Somewhere I have an old .45 Auto case I found at the range that was heavily corroded and that I put through this process. I can't recall if much pink was left after polishing or not. I'll keep an eye peeled for it and post a photo if it turns up.
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Old February 13, 2013, 02:29 PM   #25
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Quote:
acid is necessary to create current flow to make a battery.
Not exactly. An electrolyte is necessary to allow current flow to make a battery (and create galvanic corrosion). The only requirement of an a electrolyte is that it be a conducting fluid. Bases work as well as acids, and you can construct neutral electrolytes.

Sea water is a basic electrolyte with a PH around 8. Distilled water and sodium chloride would yield an electrolytic solution with a neutral ph (neither acid nor base)--but it would support galvanic corrosion like no tomorrow!
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