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Thread: Citric acid brass cleaner

  1. #81
    Boolit Master

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    Passivation of stainless steel is typically done with nitric acid. The point is to remove any
    bits of iron or steel that are providing local points of electrochemical difference which can
    cause corrosion. Clean with a strong alkali cleaner like 409 or castrol purple, plug the muzzle
    and pour in some 20-50% nitric acid and leave for about 30 minutes or more with the weaker
    solutions. Actual treatments are often done at higher than room temp.

    In addition to removing the contamination, it also creates an oxide film which protects
    against further corrosion. I have seen cases of severe corrosion of stainless steel because
    it was never passivated.

    Bill
    Last edited by MtGun44; 05-14-2010 at 12:58 AM.
    If it was easy, anybody could do it.

  2. #82
    Boolit Master sagacious's Avatar
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    Quote Originally Posted by geargnasher View Post
    ...
    Sagacious, acid scarification is common practice in seed germination, as many seeds have evolved to require digestion to break the surface enough to allow air/water inside to initiate the process.
    See, just goes to show ya learn something new every day! I was familiar with abrasive, fire, and microbial scarification. The acid scarification was a new one, but I reckon it's the same idea as gastric scarification. Is this a general practice that one could use for gardening? I get so/so gemination from melon seeds. I have scarified with sandpaper, but is a citric acid wash better alone, or is a combo OK?

    One question for the Chemists: The factory stainless steel barrel of my 10-22 keeps getting nasty rust spots on it just sitting inside by the back door, would it be possible to treat the barrel (after removing it from the action, of course) in citric acid solution to calm this down? 140* for an hour, perhaps?

    Gear
    Yes, exactly. The solution should remove the rust and passivate the surface. Clean the barrel inside and out thoroughly. I would not advise heating beyond 140*F for so. Use a 10%max solution and soak for an hour. You must air-dry for 24 hours+ after passivation-- warm air drying is best. Do not apply oil before then.

    Note to others: Citric acid will remove rust from carbon steel. It will also remove gun bluing, so do not soak a steel/chromoly barrel unless you intend to refishing it.

  3. #83
    Boolit Master sagacious's Avatar
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    Quote Originally Posted by MtGun44 View Post
    Passivation of stainless steel is typically done with nitric acid.
    ...
    In addition to removing the contamination, it also creates an oxide film which protects against further corrosion. I have seen cases of severe corrosion of stainless steel because it was never passivated.

    Bill
    Bill,
    Nitric and other mineral acids are rapidly being replaced by citric acid in industrial passivation of stainless steel and other metals.

    Why? Citric actually works much better than nitric, and is also much safer than fuming nitric acid. Coors did a lot of pioneering testing that determined that citric was a better passivation agent-- and many believe that this is why many beers taste better these days.

    Citric only removes free iron from the surface, so the passivation layer is measurably deeper than with nitric. Nitric removes the entire surface. That means nitric baths have heavy nickel and chromium loads, and the hexavalent chromium is very hard to remove-- so you've now got heavy metal disposal issues. Etc, etc. Citric is much better. Most metallurgists learned about passivation with nitric, and there's still occasional arguments about it (mainly between older and younger scientists)-- but there's no argument in industry, which tells one something. If they're using it, it must work.

    The passivation layer is actually formed in air after reaction in the passivation bath. The chromium oxides form in air, so air drying is critical. Heating while air drying speeds up the formation of the passivation layer.

    Not arguing, just sayin'. Not every day that a better/safer chemical process comes along.

    Regards!

  4. #84
    Boolit Master Murphy's Avatar
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    Okay, found the citric acid at a feed store.

    My biggest question is how to save the mix and re-heat it after using it.

    Suggestions?

    Murphy
    If I should depart this life while defending those who cannot defend themselves, then I have died the most honorable of deaths. Marc R. Murphy '2006'.

  5. #85
    Moderator Emeritus/Boolit Master in Heavens Range
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    Quote Originally Posted by geargnasher View Post
    One question for the Chemists: The factory stainless steel barrel of my 10-22 keeps getting nasty rust spots on it just sitting inside by the back door, would it be possible to treat the barrel (after removing it from the action, of course) in citric acid solution to calm this down? 140* for an hour, perhaps? Gear
    Surface passivation of metals, especially stainless, it a pretty rigorous operation, at least when done industrially. But there's stilll hope; I once lived in a really damp house, and was having to thoroughly clean all my guns every two weeks, or I would pick up rust on a cleaning rag. I tried everything on the market, and found little or no difference between them: All resulted in rust within two weeks until I tried RIG. That stands for Rust Inhibiting Grease. I wiped them down with an invisibly thin film of RIG, and no rust after one week. No rust after two weeks. No rust after a month. No rust after two months. No rust after a year. And that's when I ended the test. I've used nothing but RIG and have had no rusting problems for something like 30 years. If anything, your stainless barrel should be even more resistant if you treat it with RIG. And, no, I have no stock or other commercial interest in the product.
    Regards,

    Molly

    "The remedy for evil men is not the abrogation of the rights of law abiding citizens. The remedy for evil men is the gallows." Thomas Jefferson

  6. #86
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    Quote Originally Posted by Murphy View Post
    Okay, found the citric acid at a feed store.

    My biggest question is how to save the mix and re-heat it after using it.

    Suggestions?

    Murphy


    Maybee old crock pot?

  7. #87
    Boolit Master Murphy's Avatar
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    NSP64,

    I was wondering about that as a possibility. They're relatively cheap and can be found at garage sales, etc.

    I was thinking just scooping out the cleaned brass, letting it get back up to temp & adding more citric acid.

    Heck, I found my citric acid at the local feed store for just under $3 for 14 oz. Not like it's a huge expense.

    Thanks for your input.

    Murphy
    If I should depart this life while defending those who cannot defend themselves, then I have died the most honorable of deaths. Marc R. Murphy '2006'.

  8. #88
    Anti-Socialist Texan


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    Thanks for all the tips on the SS barrel, it's just cosmetic surface rust on the outside, bore is fine due to the nature of .22 rimfire. I'll try the warm citric acid solution bath and a warm air dry first.

    Sagacious, I'm not much of a germination expert (I was educated as an engineer), but I have a friend who dabbles extensively in native plant cultivation and have picked up on a few things from him. Seems that gourd seeds are among those that benefit from an acid treatment since they are mostly consumed by warm-blooded creatures with acidic stomachs. Bluebonnet seeds need to be treated like passing through a bird's crop and stomach, which means sandpaper and weak hydrochloric acid (muriatic).

    Gear
    You can't fix Stupid, but you can occasionally head it off before it hurts something. --Stephen Adams

    To universalize one's experience and state it as the norm is always thin ice on which to stand.--CharGar

    Being able to separate the wheat from the chaff has always been a valuable skill in all of life's activities. --Bwana


  9. #89
    Boolit Master sagacious's Avatar
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    Quote Originally Posted by geargnasher View Post
    ...
    Seems that gourd seeds are among those that benefit from an acid treatment since they are mostly consumed by warm-blooded creatures with acidic stomachs. Bluebonnet seeds need to be treated like passing through a bird's crop and stomach, which means sandpaper and weak hydrochloric acid (muriatic).

    Gear
    Gear,
    Your comments prompted me to think exactly that-- the gourd seed/gastric scarification/animal connection. Thanks very much for the spark of insight. I'm sure my garden will be the better for it.

    The 'rub' with passivation is that generally one cannot visibly see any change on the stainless steel. You should, however, see that the rust is gone. In some stainless steels, I have noticed that they 'feel' different after passivation-- small stainless parts have a very slight 'stickiness' when in contact immediately after removal from the passivation bath. I passivate stainless to be used in saltwater, and so far so good. If you guessed 140*F for an hour in a 10* solution... then you guessed right on the money.

    You can test ss passivation by placing a small amount of a 20% CuSO4 (and 1% H2SO4) solution on the stainless for 6 minutes and carefully inspecting for metallic copper deposits afterward. Citric acid passivation passes ASTM testing standards, and if curious, one can look up their standards specification for passivation and testing. Good luck.

  10. #90
    Boolit Master sagacious's Avatar
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    Quote Originally Posted by Murphy View Post
    Okay, found the citric acid at a feed store.

    My biggest question is how to save the mix and re-heat it after using it.

    Suggestions?

    Murphy
    Murphy,
    A plastic gallon milk/juice jug works very well as a storage container for the solution. A large tupperware beverage container or similar would also work well, and a 2-liter soda bottle will suffice as a storage container. A 1-gal, 3-gal or 5-gal plastic bucket w/snap-lid is excellent for storing/using a larger amount of solution. Be sure to label the container: CITRIC ACID SOLUTION.

    Do not store/use it in anything metal, and I would recommend against storage in an enamelled crock pot. I once stored an acid solution in a large enamelled pot (leather tanning solution) and it slightly etched the enamel at the waterline. Not sure that would happen with citric acid, but during long term storage, microbial action could etch the enamel in the same way. Storage in plastic is best.

    You can reheat the solution in a microwave (be sure to reheat in a glass bowl). I often use large Pyrex glass bowls for soaking the brass. Or you can just make a new batch using hot water, as your citric acid source is very inexpensive. Otherwise, a room temp soak works fine-- just takes a bit longer, but won't hurt anything. Good luck.

  11. #91
    Boolit Master


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    I'm curious as to the use that a feed store would stock it for? Animal feed additive? Seed treatment?

  12. #92
    Boolit Master rondog's Avatar
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    I'd use an empty windshield washer fluid jug for storage. Those are usually thicker, heavier plastic than milk or water jugs. They're also great to use for walking around picking up brass, I cut out the top to open it up a little but leave the handle.

  13. #93
    Boolit Man Lavid2002's Avatar
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    This thread inspired me to try to shine up some range brass. Put it in a bucket with hot water, lemon, and vinegar. After a few minutes the insides were a lot cleaner, the outside was noticeably cleaner, but not *Brand new* looking...Close

    -Dave

  14. #94
    Boolit Master
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    Reemphasis of a point above -- if you are storing any chemical or mix of chemicals in a non-original container -- LABEL IT IN AN OBVIOUS AND DURABLE WAY.

    I have seen a few mistakes with mislabeled chemicals and they can be anywhere from inconvenient to dangerous.
    Paul

  15. #95
    Boolit Master Murphy's Avatar
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    DLCTEX,

    The citric acid I found was in a package. The instructions were targeted at use for cleaning water lines. No mixing of the acid in foods/feed were mentioned on the packaging.

    Murphy
    If I should depart this life while defending those who cannot defend themselves, then I have died the most honorable of deaths. Marc R. Murphy '2006'.

  16. #96
    Boolit Master

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    Sagacious,

    Interesting that citric acid is finding so many uses these day. Our passivation has always
    used nitric in the past, but I mostly work with stress analysis, only run across the factory
    stuff incendental to a particular project. So my company may have switched to citric acid
    and I wouldn't necessarily have known it, don't have contact with the factory day to day.
    Your point about chromium ions is a very big deal. From the little bit I know chrome 6 is
    very nasty, so creating it unecessarily would be a huge problem in industry.

    I'm going to have to locate a source of citric acid. I'll be dipping my .30-06 necks in the
    goo-gone later today to try to get the asphalt sealer residue out - they are unfired so
    I think they have a lot more asphalt than fired brass.

    Bill
    If it was easy, anybody could do it.

  17. #97
    Boolit Man JesseCJC's Avatar
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    Not sure if it has been posted but you fellas lookin for citric acid should look no further than your local walmart or grocer. I use a product called lemishine with great results and it's found with the dish detergent and is about 4 bucks. Apologies if this has been posted as I have not read the thread in its entirety

    Here are my results
    A repost of my quote

    just bought some of this lemi-shine for 4 bucks. Might have over did it with the water as I filled the gallon up but I can already notice a difference. I will post up the before and edit for a follow up tomorrow.



    As you can see some are just straight brown and this is even post corncob tumble with brass polish. I threw in about 500-600 total pieces in a 1 gallon with 5 tbsp of the lemishine and topped it off with hot water.


    well needless to say, it works fantastically



    The slight pinkish tint was from over concentrating the solution with the lemishine. I use now about 2-3 tablespoons per gallon of water and yes, the solution is reusable.
    Last edited by JesseCJC; 05-15-2010 at 08:26 PM.

  18. #98
    Boolit Master

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    Looks great. At first the second pic looks like nickeled brass! I'll start with
    Lemishine, and keep an eye out for citric acid.

    Bill
    If it was easy, anybody could do it.

  19. #99
    Boolit Master sagacious's Avatar
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    Bill,
    I agree; the breadth of application of citric acid is amazing. In a time when "chemicals" are viewed with increasing suspicion by the general public, citric acid is likely to carve out an even deeper niche. Good luck with the tar sealant-- like you I had a whole bunch of unfired/pulled 30-06 military cases, and I treated them successfully with Goo-Gone.

    JesseCJC,
    Thank you very much for posting the info about Lemishine. That will undoubtedly prove to be a convenient source of citric acid for many people. The brass looks great.

  20. #100
    Boolit Master
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    Talking

    JesseCJC, how long did you let the cases soak in the Lemishine.

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