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Technical citric acid

Discussion in 'The Hokey Ass Message Board' started by msgt tank, Apr 22, 2020.

  1. For small parts in a smaller bucket, I picked up a Kitchen Aid strainer in the supermarket. I made a handle from safety wire and hook it over the edge of the vessel. Old cat litter pails with covers are pretty good for a small batch.
     
  2. jdcool44
    Joined: Jul 24, 2019
    Posts: 53

    jdcool44
    Member

    Can some one tell me the purpose of the agitation? Just to knock the rust loose? Or dose the acid fall out of suspension? I am doing a small test in a tote can I just give it a shake every few hours?
     
  3. error404
    Joined: Dec 11, 2012
    Posts: 277

    error404
    Member
    from CA

    Citric acid will also strip zinc coatings off of new hardware. I use citric acid when I'm going to weld zinc coated hardware, I don't want to breath that stuff in. over night seem to remove most of the coatings. :)

    I like citric acid because it's faster than vinegar, but yet still safe enough to dump down the drain.

    I used to get it from the local baking supply store.
     
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  4. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,120

    ekimneirbo
    Member
    from Brooks Ky

    To me, the purpose is to cause some flow thru areas like water jackets so as the rust comes loose it doesn't just settle somewhere else in the jacket. It probably doesn't hurt with keeping the acid and water mixture consistent as well.
     
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  5. Finnrodder
    Joined: Oct 18, 2009
    Posts: 2,955

    Finnrodder
    ALLIANCE MEMBER
    from Finland

    Citric acid is great stuff, i have used it with good results. I bought a kid's pool and made around 220 gallons mixture of that stuff. Its a lot, but i needed that much to get shoebox hood and NOS door cleaned from surface rust. It works fine on sheetmetal, but springsteel gets ruined with citric acid.

    IMG_5251 (Custom).JPG IMG_5254 (Custom).JPG IMG_5267 (Custom).JPG IMG_5272 (Custom).JPG IMG_5371 (Custom).JPG IMG_5384 (Custom).JPG IMG_5386 (Custom).JPG
     
  6. Finnrodder
    Joined: Oct 18, 2009
    Posts: 2,955

    Finnrodder
    ALLIANCE MEMBER
    from Finland

    This how i do it:
    1. I rinse all the loose dirt or use degreaser to get all the loose crap out of the piece.
    2. I sunk the the piece in citric acid mixture and let it be there over 24 hrs, it doesnt hurt if its there a bit longer.
    3. I rinse the piece and brush it with steel brush. This will make the process faster. I used a powerwasher on those bigger pieces i did. Powerwasher is good way to clean them, but not so handy on smaller pieces.
    4. I sunk the piece again in mixture for next 24 hrs or so. Usually these 2 baths have done the trick. If not, i repeat the rinsing and bathing the piece.
    5. I rinse the piece again and if i am happy with the result, i make sure its rinsed properly and dry the piece with a heatgun. The heat will neutralize the acid. After it is dryed and cooled down, i spray primer on the piece. If you leave it after drying it, its starts to get rusty again.
    I hope that helps.
     
  7. Budget36
    Joined: Nov 29, 2014
    Posts: 3,474

    Budget36
    Member

    Anyone know what it would do to brass core plugs?
     
  8. Brass is OK in strong cleaning vinegar . Potmetal is not . Aluminium will also slowly disolve.
     
  9. error404
    Joined: Dec 11, 2012
    Posts: 277

    error404
    Member
    from CA

    Very interesting! What happened to the spring steel?
     
  10. Finnrodder
    Joined: Oct 18, 2009
    Posts: 2,955

    Finnrodder
    ALLIANCE MEMBER
    from Finland

    I have heard that the cast metal and hardened steels like spring steel are a big no no with citric acid. The cast metal will be fragile after the bath and hardened steels will disapear in the long run.
    I have no experience with cast metals and citric acid, but i have some with hardened steels and citric acid.
    I had a set of headliner bows, i throw them in the mixture bath and this is completely my own fault what happened next. I forget them in the bath for few weeks and when i picked them up from the tank, they were completely ruined. They were really thin, a lot of material from the bows had disappeared. They werent that rusty, that there were almost anything left of them. So only explanation for that must be that the bows are hardened steel originally.
    If someone wants to try what happens for shits & giggles, go ahead. But i am not trying that shit anymore, lesson learned:D
    Well, i have to find an another set of '49 to '51 Ford tudor headliner bows somewhere..
     
  11. Inked Monkey
    Joined: Apr 19, 2011
    Posts: 1,776

    Inked Monkey
    Member

    Hmm, I was going to soak an A front spring. But after reading that, maybe I shouldn't.
     
  12. stanlow69
    Joined: Feb 21, 2010
    Posts: 4,333

    stanlow69
    Member
    from red oak

    @Finnrodder You have a very strong batch if the hood and doors were cleaned of rust that fast. No wonder your headliner bows whittled away. I put seat frames with springs in my tank for a week or two depending how rusty they are. Sometimes longer with is often. No problems thus far. @Inked Monkey You should not have a problem with your springs. If concerned, check them daily. But that`s if you are paranoid. I have an item that`s been in my tank for 9 months. It`s an old shoe shop machine. Will be getting it out shortly. it`s heavy and I kind of forgot about it. Got 100 pounds in yesterday for my tank. Won`t use it all at once. My old batch is 4 years old.
     
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  13. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,120

    ekimneirbo
    Member
    from Brooks Ky

    Since the citric acid does its work from the outside of any part, it would seem that thick heavy items should be fine in most citric acid bathes for a short term.......then resubmerge if they need a little more derusting. Thinner items obviously should be checked after a few hours and then proceed from there.
     
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  14. Finnrodder
    Joined: Oct 18, 2009
    Posts: 2,955

    Finnrodder
    ALLIANCE MEMBER
    from Finland

    Its not that strong, i use 5% mixture. Some people have suggested that 7% is a correct mixture and other say that 3% is the most effective. So i have used something between them, that 5% has worked fine with me. I have also heard that heating the mixture will make it more effective, but the process has been fine without any extra heat.
    Like i said, that headliner bow failure is completely my own mistake and its my only bad experience with citric acid. It was a huge WTF moment, when i get them out of the tank. I noticed that i havent get rid of those yet, i dug them out of the junk pile and took a pic. The thicker one is near std size and those welding wire looking things are what are left of my headliner bows.

    IMG_20200708_220645_8 (Custom).jpg
     
  15. A good, inexpensive place to get citric acid, is at the Bulk Barn, if you have one in your area.
    Bob
     
  16. stanlow69
    Joined: Feb 21, 2010
    Posts: 4,333

    stanlow69
    Member
    from red oak

    @Finnrodder Just reafirmming Ink Monkey it would be safe for his spring.
     
  17. Finnrodder
    Joined: Oct 18, 2009
    Posts: 2,955

    Finnrodder
    ALLIANCE MEMBER
    from Finland

    No problemo, just shared my good and bad experiences with this method.
     
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  18. Crocodile
    Joined: Jun 16, 2016
    Posts: 202

    Crocodile
    Member

    Does anyone know if the citric acid ruins fiberglass? I have some wood shipping "coffins" that I saved from work, with the idea of lining them with a layer of fiberglass to use for a citric acid tank and a neutralizer tank. They are a nice size for fenders and probably most doors, so they would be ideal if a fiberglass liner would hold up.
     
  19. stanlow69
    Joined: Feb 21, 2010
    Posts: 4,333

    stanlow69
    Member
    from red oak

    Draining my IMG_20200712_0003.jpg IMG_20200712_0004.jpg IMG_20200712_0005.jpg 3 year old batch. And in with the new.
     
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  20. treb11
    Joined: Jan 21, 2006
    Posts: 3,464

    treb11
    ALLIANCE MEMBER

    Just use a heavy plastic sheet such as thst used under coccrete home foundations
    Sent from my SM-G965U using The H.A.M.B. mobile app
     
  21. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,120

    ekimneirbo
    Member
    from Brooks Ky

    Agree with treb11, use a black plastic dropcloth to line the box. I did that several years ago for an electrolisis setup. I figure someone could actually build a long flat rectangle and lay a drop cloth in it and do a frame. Then use the lumber for something else when done.
    Obviously you can't put things with sharp edges in it unless you suspend them so they don't poke the liner.
     
  22. Six Ball
    Joined: Oct 8, 2007
    Posts: 3,340

    Six Ball
    Member
    from Nevada

    I started to do that, then I did the math. If I was in the spot to do all my frames it would have been OK. Without barrels to store the liquid for future us it wasn't worth it. I have the wood and plastic someone near want to do a frame party? I'm almost done blasting mine now.
    After re-reading here I did the math again. What I was setting up was 14' x 4' x 1'. It would hold about 420 gallons. Using 1lb acid to 5gal water it would take 84 lb. Using the 1 cup to 3 gal ratio it would be 47lbs of acid. That is a lot better than what I came up with before especially if I did the 4 frames I have sitting around along with all the other parts that would fit into it. By changing the shape to take the frame sitting on it's side and 2' deep It would take less but fewer other parts would fit. I am almost done blasting my frame so I doubt if I'll do this for now. I do have a large tank that will fit everything else.
    200707_0007.jpg
     
    Last edited: Jul 14, 2020

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