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  1. #16
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    Why would it matter if there was some exposed metal? The rust is removed from the part to the electrodes and if the tub is connected to the electrodes as part of that same side of the circuit it would receive some of the rust too. It shouldn't be eroded and leak. Just make sure it is insulated from the ground and the part is insulated from the tub by some non-conductive spacers. Right?

    Pete

  2. #17
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    Quote Originally Posted by QC Inspector View Post
    Why would it matter if there was some exposed metal? The rust is removed from the part to the electrodes and if the tub is connected to the electrodes as part of that same side of the circuit it would receive some of the rust too. It shouldn't be eroded and leak. Just make sure it is insulated from the ground and the part is insulated from the tub by some non-conductive spacers. Right?

    Pete
    The positive plate (anode) that receives the rust is sacrificial and will be eaten away during the process.

    Provided the bath tub is not positively connected/charged there should be no detrimental effect on it.

    Basically provided the sacrificial anode is insulated from the bath it should work fine.

    Cheers Rob
    The worst that can happen is you will fail.
    But at least you tried.



  3. #18
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by nearnexus View Post
    The positive plate (anode) that receives the rust is sacrificial and will be eaten away during the process
    The orange gunk that appears on anodes made of generic steels are not "receiving the rust" from the workpiece but the steel in the anode reacting with the oxygen generated at the anode which reacts with the steel anode to make its own rust.
    The anode rust makes a sludgy mess, insulates the anode and significantly slows the electrolysis reaction.
    If SS is used as an anode it will not be eaten away anywhere near as quickly - same for carbon rods.
    These anodes also keep the electrolysis baths much cleaner.
    SS has some potential issues with the possible production of hexavalent CrO, but provided the electrolysis tanks is well ventilated or outside it should be OK.

    RE: Bath
    Just measure the linear resistance of the enamel. If its in the MΩ/m range it should makes things easier because then you minimise connections by placing steel rods/pipe across the edges of the bath and suspend the parts and anode(s) from these pipes.
    If the enamel is conductive then you will need to insulate the ends of the rods/pipes touching the edges of the bath (ie some short bits of poly)

    If your parts are large, multiple anodes surrounding the part are recommended other wise you will have to repeated turn the parts around/over.

  4. #19
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    I got the old bath out, put silastic over all the chips, Had a bit of builder plastic, enough to cover 1/2 up the sides,
    Put the smaller cabinet in,anode each end, filled the bath, covered 9/10 of the cabinet, switch it on, all appears to be working fine.

    Ratty 05/2004 -05/07/2010 COOPER 01/08/1998-31/01/2012

  5. #20
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    Quote Originally Posted by wm460 View Post
    I have got a bottle of Evaporust
    On another forum I saw someone who made a trough just big enough to do one side of the bed at a time.


    My maths tells me I would need 2.2lts proberly 2.5lts with the evaparation here.
    Nearest available to me is MT Isa Supercheap, $42.99 per lts plus freight.



    Quote Originally Posted by BobL View Post
    I'd rather spend it on more/other chemicals to fart around with
    Me too.

    Ratty 05/2004 -05/07/2010 COOPER 01/08/1998-31/01/2012

  6. #21
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    If I use either Electroisis or the Citric acid (when it finally arrives) will either harm the bog on the lathe bed?

    Ratty 05/2004 -05/07/2010 COOPER 01/08/1998-31/01/2012

  7. #22
    BobL is online now Member: Blue and white apron brigade
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    Citric acid shouldn’t do much to paint or bog. Electrolysis is usually done in an alkaline solution so it will attack paint but it depends on the type of bog used. Maybe try out a not very important piece first?

  8. #23
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    My citric acid finally turned up, is this correct 10Lts :1gm ratio of water to citric acid powder?

    Ratty 05/2004 -05/07/2010 COOPER 01/08/1998-31/01/2012

  9. #24
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by wm460 View Post
    My citric acid finally turned up, is this correct 10Lts :1gm ratio of water to citric acid powder?
    A 10% solution will be ~1kg of powder to 10L of water.
    I'd try 5% to start with, 500 g of powder to 10L of water

  10. #25
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    Quote Originally Posted by BobL View Post
    A 10% solution will be ~1kg of powder to 10L of water.
    I'd try 5% to start with, 500 g of powder to 10L of water

    Thanks Bob.

    Ratty 05/2004 -05/07/2010 COOPER 01/08/1998-31/01/2012

  11. #26
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    I am totally converted to citric acid now.
    I first tried an old vice that I had first put in an electrolysis bath a few days before, when it came out of the citric it was 150 % better that the the electrolysis.
    Now on the second batch of Hercus parts.

    Ratty 05/2004 -05/07/2010 COOPER 01/08/1998-31/01/2012

  12. #27
    BobL is online now Member: Blue and white apron brigade
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    Same here. On large parts I found unless multiple electrodes were used with electrolysis the removal was uneven so the workpiece needed to be moved around. And it could be quite messy even when using inert electrodes. Citric etc acid baths are basically immerse and forget. For really thick rust I still sometimes use electrolysis but if possible it’s easier/quicker to get them onto a wire wheel first..

  13. #28
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    I also found using electrolysis, if the aboriginal mob behind me have fight my dogs quickly go to investigate, they just go like a bat out of hell knocking my anode over twice.
    DSC_2224.JPG

    Ratty 05/2004 -05/07/2010 COOPER 01/08/1998-31/01/2012

  14. #29
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    I'd always go with electrolysis over any of the acids, I did a bit of semi-scientific testing with some clean steel: measured it with a tenths micrometer, deliberately rusted it (with half each sample painted over to prevent rusting), then stripped the paint with methylene chloride and a toothbrush, cleaned the samples with electrolysis, citric, oxalic, muriatic and phosphoric acid - and found that the electrolysis sample showed no removal of sound metal, the phosphoric, oxalic and citric removed close to a tenth, muriatic - don't go there!

    I don't use steel for the sacrificial anodes, I use graphite plates and (although expensive unless raided from a very techy skip) they seem to last forever (frequent use over the last year or more, still on the same plates) and there's no build-up of rust barnacles needing scraping off.

    Many folks don't use enough anode area, it wants at least the area of the work being cleaned up - e.g. a bench shear I cleaned ran close to 20 amps, cleaned up in a day or so.

    Dave H. (the other one)

  15. #30
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    Just got back from Dads funeral, just made it over the border in time, I have to spend 14 days home not in some motel room.
    When I looked at the small covered tub that I citric acid in I found a lot of mould floating on top, is this OK to use after removing the mould?

    The bath tub with a sheet of corrugated iron on to had evaporated about 300 mm, put a old anvil in it 24 hrs later nice and clean.

    Ratty 05/2004 -05/07/2010 COOPER 01/08/1998-31/01/2012

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