Phosphoric acid rust removal

Discussion in 'Paint and Body' started by Eric Winkworth, Nov 3, 2011.

  1. Eric Winkworth

    Eric Winkworth

    Messages:
    2,044
    I finally sourced some Phosphoric acid (85%) and I am curious if anyone else has used it on their land cruisers. I have a few spots on the truck that I've rattle canned to try and keep the rust off but it keeps coming back... This time I'm also going to use a good epoxy primer and top coat....

    Will just brushing this on waiting and wire wheeling then repeat until the rust is gone be effective?

    Thoughts, comments and stories?
  2. MANUCHAO

    MANUCHAO omnea mea mecum porto SILVER Star

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    3,539
    Location:
    Sur Cal
    I have used Muratic acid (almost or same as what you use) and after letting it sit on the rusty areas until its tacky just about to dry off.. I spray or use POR15... it helps the pain adhere a lot better
  3. Eric Winkworth

    Eric Winkworth

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    2,044
    Not that I'm an expert but many forums and articles I've read say muratic acid is way more agressive an acid, not only that it also eats clean metal and will continue eating metal unit it is neutrlized. How long has the POR been on there? How's it holding up? Phosphoric acid will only eat rust until it burns itself out and become inert leaving a thin rust inhibiting coating... This is all just what I've read no first hand experience yet...
  4. I get my phosphoric acid at home depot in the paint dept. $14/ half gallon. Works great, but slow to remove mill scale, and actually protects the metal via a chemical process.
    Once I am done, wash with TSP and dry with a 50% blend of water and alcohol rubdown. Minimizes flash rust and speeds drying
  5. markthemenace

    markthemenace

    Messages:
    430
    Location:
    Pitt Meadows BC
    Hi there, I've been to Home Depot, Rona and Canadian Tire...at all three places, I could not find Phosphoric Acid. I'm heading into Christmas vacation time now and would really like to get started on the rusty frame that my Cruiser has. What better way to spend my vacation time eh...under the Cruiser :D

    So, anyone with ideas on where to buy Phosphoric Acid in Canada, please let me know!

    BTW, the HD guys tried to sell me an "environmentally friendly" alternative to Phosphoric Acid, but when I described why I need it for, he told me it won't work.
  6. spotcruiser

    spotcruiser Geezer SILVER Star

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    2,373
    Location:
    Western WA
    Look for Jasco Prime & Paint. Home Depot and Lowe's have it in Washington.
  7. markthemenace

    markthemenace

    Messages:
    430
    Location:
    Pitt Meadows BC
    Thanks! I'll have to get it next trip down then. Wonder why nothing's available over here. I'll pop by IPP today though to see if they have anything.
  8. Icantdive55

    Icantdive55 SILVER Star

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    Location:
    N. Calif. Redding
    http://forum.ih8mud.com/fj25-owners-group/316460-rods-65-fj-40-thread-8.html#post7191519

    In my rebuild thread I have used the Phosphoric acid. I think it woorks very well. the pictures in the link above don't tell the whole story. The blaster I used to try and clean the metal works very well on paint and light rust. The stuff in the photo wasn't even responding to the wire brush in a 4" grinder. All the grinder was doing was shine the rust. Given enough time I'm sure it would have worked but the Prep & Etch at HD works MUCH faster. It's still not quick but it's the only thing that works for me.
  9. spressomon

    spressomon glutton

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    11,183
    Location:
    Central Coast

    As above...straight white vinegar works too on parts that can be submerged. Because its only 6% acid solution it just takes longer than phosphoric acid or muriatic acid (muriatic acid only takes seconds to minutes). When you pull them out of the soak, could be 2-3 days depending upon how much rust on the parts, rinse the part under hot water...a little easy scrub with a bristle brush helps too...then immediately dry the parts.

    Works great for me...
  10. markthemenace

    markthemenace

    Messages:
    430
    Location:
    Pitt Meadows BC
    Thanks for sharing your experience Rod. Yeah what you're doing parallels my intention somewhat. In my case I'm trying to fix a rusty frame. That 1 Gal Klean Strip is EXACTLY what I need, but is nowhere to be found here in metro Vancouver. For some reason, phosphoric acid is a bad word here!

    That vinegar idea would be good for small parts, but for the frame, no. :D
  11. 45Kevin

    45Kevin

    Messages:
    1,754
    Location:
    Calgary, Alberta
    We used to put corroded metal that we found while diving into Coke to get the rust off.

    That's the classic coke; not sure how the diet or zero would work.

  12. e9999

    e9999 You want to do what...? Moderator

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    15,229
    Location:
    PRK
    phos acid works great.
    I just got some at Home Deport for $15 a gallon (around 50% strength). It's sold among other ways as a cleaner / etcher.
    I just did a rusty cast iron grill grate a couple of days ago. It looks brand new now. And so easy. Just spray with a bottle and let sit for a while very wet, repeat as necessary, then rinse (don't let it dry on as there will be unsightly deposits).

    Some Naval Jelly also contains phos acid but did not work well at all for my needs. Not as strong and has to be brushed on, which is a pain for intricate big stuff. And much more expensive. But that might be better for body or frame work as it won't drip.

    A good thing about the phos acid is that it'll leave a phosphate coating which is supposedly somewhat rough/porous and would therefore in principle soak up oil (as in Parkerizing maybe) or make a good substrate for paint.
  13. markthemenace

    markthemenace

    Messages:
    430
    Location:
    Pitt Meadows BC
    In my research, I've also come across the use of tannic acid as leaving a superior coating. Any ideas where to get that?
  14. cuteo100

    cuteo100

    Messages:
    241
    Location:
    Southern California
    I put phosphoric acid on my FJ45 bed before rattle canned priming and painting. It works supper! Good to go for another decade, lol!

    [​IMG]
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    Last edited: Feb 29, 2012
  15. markthemenace

    markthemenace

    Messages:
    430
    Location:
    Pitt Meadows BC
    Well, I drove down to Lynden the other day, and the guy at the hardware store told me that Phosphoric Acid is no longer allowed in Whatcom County. So I guess BC must be the same, which explains why I can't find it anywhere.

    I've got a whole bottle of Evaporust that I used in the restoration of an old Lee Enfield that worked wonders for parts soaked in it. However, I can't possibly soak the frame...so, I'm going to try brushing it on and seeing if it works. I've run out of options it seems...
  16. yoopercharged

    yoopercharged SILVER Star

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    Marquette,MI
  17. Runamuck

    Runamuck SILVER Star

    Messages:
    97
    Location:
    Madison, Alabama
    Best way to remove rust - Get a 20 gallon plastic bucket at Home Depot or Lowes. Get a metal air flow duct that fits into the bucket leaving room around the edges of the bucket. Have a battery charger with about 8 or so amps. Go to grocery store and get a big box of baking soda. Supplies will cost you less than a gallon of the acid (minus the batter charger).

    Fill the 20 gallon bucket with water mixing one tablespoon of baking soda to each gallon of water. Lower the metal tube duct into the bucket having about an inch or two of the rim above the water.

    Attach the positive charge from the battery charger to the metal duct being careful not to touch the water with positive clip (it needs to stay dry).

    Attach the negative clip firmly to the part you are trying to de-rust. Lower the part into the center of the duct being careful not to touch it to the positively charged metal ring. If you touch the water while lowering the part in the bucket, you will feel a stinging sensation. It wont shock you but it is unpleasant after a while (experience talking).

    If you do it correctly, bubbles will begin to form on the part and after a while the rust will begin to collect on the positive charged metal. Leaving it over night, you will find a bucket full of nasty foam stuff, the sacrificed metal covered with rust and your part clean as new.

    This is the cheapest and best way I have found to remove rust on parts that can fit in a 20 gallon bucket. For bigger parts, I suppose a bigger tub would work just as well.
  18. westgate

    westgate

    Messages:
    12
    Location:
    new westminster b.c.
    rust mort

    hey in B.C. you can buy a product called RustMort.
    it is sold at KMStools.
    cheap enough, and its phos. acid.

    hope that helps you out.
  19. Toyodieselfan

    Toyodieselfan

    Messages:
    401
    Location:
    orlando FL.
    Yep home depot has it ( phosphoric acid) after reading the thread I went to HD and bought a galon jug $15 bucks good deal. Find someone who crosses the border regularly to bring some.
  20. Icantdive55

    Icantdive55 SILVER Star

    Messages:
    461
    Location:
    N. Calif. Redding
    My HD quit stocking it. After looking all over for it I finally found it at the Paint Mart. They sell all types of paint and they sell the prep and etch for doing the prep on metal. It was 18$ for a gallon. I built a small wooden box lined it with heavy plastic. It's the right size to fit my seat feames. I diluted it 3 to 1 and let the items soak for a day or two. Been working great! The directions say full strength on rust as heavy as I have but I couldn't afford to drop over 100$ at the time so I cut it 3 to 1 and let it soak a little longer.

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