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  1. #1
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    Default Backyard Phosphating

    Below are examples of tooling that have what I think is a grey phosphate finish to their non ground surfaces.

    IMG_20190711_163830411.jpg

    The arbor on the left is a 2 Morse adaptor for which I made a drawbar coupling from 4140. To replicate ( or come close to replicating ) the original grey, I applied Rust-Off to the coupling, initially by immersion followed by application with some paper towel dampened with the Rust-Off.

    IMG_20190711_163846457.jpg IMG_20190301_121821633.jpg

    BobL suggested using Rust-Off as a rust converter a couple of years ago because of its 62.5% phosphoric acid content. It is available from Bunnings. The container on the left shows the current label.

    IMG_20190531_161418820_HDR.jpg

    So far I have only applied the Rust-Off to 4140. The example below is a "drawbar" for P20 collets. Behind it is a bar end of precision ground 4140 for comparison.

    IMG_20190711_162914646.jpg

    And on a slightly smaller scale, an M4 threaded replacement thumbscrew for my daughter's piercing saw. She broke the screw last night. She lives in Melbourne. We both have the same saw.

    Before and after the Rust-Off with an original screw on the left -

    IMG_20190711_110646064.jpg IMG_20190711_113551329.jpg IMG_20190711_114310076.jpg

    I am yet to try "phosphating" the ever so keen to corrode 1214. Next experiment unless Bob beats me to it.

    BT

  2. #2
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    Default

    Anorak Bob

    I will be trying this on some plain old 1020. How long did you apply it for?

    Eric

  3. #3
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    Quote Originally Posted by lamestllama View Post
    Anorak Bob

    I will be trying this on some plain old 1020. How long did you apply it for?

    Eric
    The duration is something you need to experiment with Eric. Totally immersed, not a lot happens rapidly but when exposed to oxygen the process accelerates. Bob suggested heating the acid to hasten its effect but I have not yet tried it.

    The little thumbscrew would not have taken more than 5 minutes of dabbing with the wet paper towel to obtain the grey finish shown.

    Keep in mind I have only used 4140.

    Bob.

  4. #4
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    Default

    Thanks for that Bob. I might have to try it on those toolholders; the originals are slightly grey so that could well be the finish applied to them. Just wondering whether an air bubbler in a tank of the stuff may be another way of getting the finish without dabbing with a paper towel. The boring way would of course to be jiggle the part in and out of solution. May have to visit the aquarium section in the local pet shop on the way home today...

    Michael

  5. #5
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    Default

    Quote Originally Posted by Anorak Bob View Post
    Bob suggested heating the acid to hasten its effect but I have not yet tried it.
    I recently blued a gun barrel with a product that contains phosphoric acid. I found that warming the barrel with a hot air gun before application dramatically increased the speed of the bluing reaction. The product also contained other chemicals so my experience may not apply to phosphoric acid alone.
    Chris

  6. #6
    BobL is offline Member: Blue and white apron brigade
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    Default

    Quote Originally Posted by Anorak Bob View Post
    BobL suggested using Rust-Off as a rust converter a couple of years ago because of its 62.5% phosphoric acid content. It is available from Bunnings. The container on the left shows the current label.

    IMG_20190531_161418820_HDR.jpg
    Have you tried the newer stuff yet?

    Just a heads up that the newer stuff is no longer just phosphoric acid and water.
    The MSDS says it contains 30-60% phosphoric acid, < 10% CITRIC Acid plus a yellow dye, <10% Ethoxylated Oleic Acid.
    I expect the two additional acids to slow down etching of bare metal and the yellow dye may even leave a colour tint on the steel.

  7. #7
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    Default

    Not yet Bob.

    Used frugally, there are many more projects left in the old bottle. I squandered some of the Rust-Off removing electrolytic zinc plating from fixings before I discovered its colourative properties.

    Bob.

  8. #8
    BobL is offline Member: Blue and white apron brigade
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    I'll leave it to AB to do the other steels, I just wanted to see (very) quickly what would happen with mild steel.

    These are my starting pieces.
    They are the same pieces I used to do the various acid dissolution of MS tests a while back
    Start.JPG
    The shinier piece was about as rusty as the middle piece and I just stripped the rust off with a wire wheel.
    The middle piece looks about as rusty as the RH piece but the RH piece definitely has the thicker rust.

    All the pieces war cleaned by ultrasonicating in 30șC IPA for about 5 minutes.
    I'm using the new Rust-off PA with citric/oelic acid in it.

    Then I soaked the LH piece in neat Phosphoric acid (PA) but to speed things up I did it in a warm (40șC) ultrasonic bath for 60s.
    There was plenty of bubbling action and a few mm of foam formed on the surface of the piece and the surface of the PA.

    This is the result.
    The small piece is the same MS cleaned up with a wire wheel.
    Clearly there has been something formed on the surface but it does not seem to have etched the surface despite the bubbling action when soaking.
    60s.JPG


    Then I soaked the rusty pieces in the same manner as the above piece but this time I did it for 10 minutes.
    Shown below after treatment is the raw steel soaked for 60s and the rusty pieces soaked for 10 minutes
    Virtually all of the rust has been removed from the middle piece and almost all of the RH piece which had the thickest rust layer.

    10m10m.JPG

    Then to see if I could build up the layer of phosphate I put the piece that had been in the PA for 60s back in for another 9 minutes so all 3 pieces had 10 minutes of exposure.
    aIt does not look like it made much of a difference - well maybe a whisker.
    60s10m.JPG

    Now I'm going to leave these outside and see how they rust.
    I've done the outside rusting of MS after treatment with painted on PA before - not very successfully, from memory rust started appearing after about a week.

  9. #9
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    If it took a week for rust to appear on your phosphated test pieces Bob, I'd call that a success. Rust forms overnight in my too well ventilated shed.

    So after typing the response above I headed back up to the shed. I noticed some rust on the unpainted machined surface of the cast iron pedestal base of the tool and cutter grinder. Wiping over the rust with a Scotchbrite pad followed by an application by paper towel of Rust-Off resulted in the formerly orange surface turning grey. Then I thought I would have a go at transforming the garishingly loud handle of the mill's whizzo vice into something a touch more subdued.

    I had made the handle from Flowcast 4E cast iron copying as closely as possible the vice's original cast iron handle. The original handle was probably paint finished black with the casting aiding paint adhesion. Mine is smooth.

    IMG_20180916_135620382.jpg

    So, gloved up, I subdued it. The Rust-Off was again applied via paper towel and grey increased in darkness with subsequent applications.

    IMG_20190712_165629103.jpg IMG_20190712_164901868.jpg IMG_20190712_170200750.jpg

    BT

  10. #10
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    Quote Originally Posted by BobL View Post
    ...Now I'm going to leave these outside and see how they rust.
    I've done the outside rusting of MS after treatment with painted on PA before - not very successfully, from memory rust started appearing after about a week.
    I can't recall whether it was Phosphating or another treatment that we used in one of the car part places I've worked in, but recall being told that it was mainly done as a keying treatment for paint; by itself the treatment did not do much but the surface is excellent for a key, and also (perhaps most importantly for us) as a semi porous surface for oil to sit, the oil sealing the surface and preventing air getting to the 'metal' surface.

    Perhaps if it is not too late in the test, try wiping part of the test pieces with an oily rag and see if that helps?

    Michael

    Added later - Just hooked out a couple of pieces that were soaking overnight and lightly oiled them. Look alright, almost like the originals did.
    Last edited by Michael G; 13th Jul 2019 at 11:13 AM. Reason: Added a bit

  11. #11
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Anorak Bob View Post
    If it took a week for rust to appear on your phosphated test pieces Bob, I'd call that a success. Rust forms overnight in my too well ventilated shed.

    BT
    That CI handle looks fantastic Bob - must try some out.

    In terms of my testing for PA longevity I found the results of the testing I did in 2015 and it lasted about a week outside (undercover) before some tiny rust spots appeared and after 23 days it looked like the photo below.

    Top one is stock MS flat bar as supplied by steel merchant
    LHS is Tannic Acid (TA) middle is bare steel, RHS is PA

    Lower one is the same but for steel sanded bright

    In both cases the steel bars were laid flat and acids were painted on (several coats) and left to dry, The TA is very thin and really benefits from multiple coats - unfortunately its not really a handleable material - the black iron tannate comes off onto your hands so it needs an over coat of something.


    23days.jpg

  12. #12
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    Default

    A question for Bob.

    What would be the best way of neutralising the phosphoric acid to prevent continuing darkening of the metal?

    Bob.

  13. #13
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    Default Promise is in the Air

    1214 without a preparatory dip in diluted hydrochloric acid to remove the smeared lead.

    IMG_20190713_093518934.jpg

  14. #14
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Anorak Bob View Post
    A question for Bob.

    What would be the best way of neutralising the phosphoric acid to prevent continuing darkening of the metal?

    Bob.
    I wouldn't use anything as it might disturb the phosphate layer, even water might initiate rust

    Suggested after treatments (in order)
    - wipe off excess PA with a cloth
    - blow dry cavities threads etc with a compressor.
    - hot air dry to ensure no remaining moisture
    - dip in warm mineral oil bath to block further interaction of air with any residual PA.

    That bit of 1214 looks interesting.

  15. #15
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    For you Bob. One on the right is oiled, one behind is from the bath and a section of cut steel that they are made from is in front.
    P1040630.JPG

    Michael

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