Hot Citric Acid Bath

  1. Wallace

    Wallace Member

    Messages:
    6,858
    Location:
    Staines, Middlesex, England.
    That's coming out nicely, well done. I have been thinking for a while that air agitation would help clean the surface. can you see inside?
     
  2. Onoff Member

    Messages:
    983
    Location:
    Sevenoaks, UK
    Will have a look in the daylight.

    Ref heating, I had the mad thought to site a blue plastic barrel in the corner of an insulated COMPOST HEAP.
     
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  3. Wallace

    Wallace Member

    Messages:
    6,858
    Location:
    Staines, Middlesex, England.
    Certainly would keep it warm! :thumbup:
     
  4. fizzy Forum Supporter

    Messages:
    5,581
    uk
    Now you are talking SH1T :clapping:
     
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  5. Onoff Member

    Messages:
    983
    Location:
    Sevenoaks, UK
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  6. Onoff Member

    Messages:
    983
    Location:
    Sevenoaks, UK
    That really worked well!

    [​IMG]

    [​IMG]

    The caliper was interesting. I took it out of the bath along with the cross member and trailing arm and jet washed the lot. Wire brushed some of the more stubborn rusty areas too.

    Took the caliper only indoors and washed it in the sink under hot water with a drop of Fairy whilst I freed the sliders off. It flash rusted so quickly afterwards. This is it flash rusted. 5 mins before it was clean steel.

    [​IMG]

    All back in the bath now.

    I wonder what a cross member would have weighed originally to calculate the material %age lost?
     
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  7. ronan

    ronan Forum Supporter

    Messages:
    9,433
    dublin
    The citric made short work of that job ! That bracket might be iron rather than steel ?
     
  8. Onoff Member

    Messages:
    983
    Location:
    Sevenoaks, UK
    Cast aren't they, calipers?
     
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  9. Onoff Member

    Messages:
    983
    Location:
    Sevenoaks, UK
    Once this cross member comes out of the acid, should I neutralise it with anything (sodium bicarbonate solution maybe?)

    Thinking of the rumoured issues SPL had with acid staying between the panels.
     
  10. ronan

    ronan Forum Supporter

    Messages:
    9,433
    dublin
    Yeah i think so.
     
  11. owas

    owas Member

    Messages:
    1,749
    Location:
    Birmingham
    I use wheel barrow tubs for mine (get them free), one for the lid and 2 for the bottom, fits everything I need to derust

    Currently got a brake disk backing plate thing in
     
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  12. Onoff Member

    Messages:
    983
    Location:
    Sevenoaks, UK
    What's that in there citric acid?

    I didn't think it was too kind to zinc as in the barrow tub coating?

    Assuming Deox-C is citric acid it says not to immerse anything zinc in it:
     
  13. owas

    owas Member

    Messages:
    1,749
    Location:
    Birmingham
    Tis ok, I have a few painted ones too, I was just curious to see what it did to the zinc
     
  14. Onoff Member

    Messages:
    983
    Location:
    Sevenoaks, UK
    For a small, one pot citric acid bath I'm thinking to take the top off a stainless steel kettle (good but for a broken lid). I can strap a cylinder stat to the side to hold it at 70degC without the kettle's own bi-metallic strip coming in and switching it off.

    Got a rusty MK4 Golf, rear wiper assembly as it's first patient!
     
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  15. anto Forum Supporter

    Messages:
    856
    Location:
    Ireland
    Does the mix need "topped up" with citric powder/ liquid every so often or does the mix just go dead after a while?
    Or is it a case that all the "rust" contaminants just build up too much and reduce effectiveness?
     
  16. rtcosic

    rtcosic Member

    The citric acid molecule chemically combines with the iron oxide so the solution will become 'exhausted'.

    I tend to cascade the solution. The new mix is used for light derusting - eg the flash rust on cast iron as mentioned above, or an electrolytically cleaned item to catch odd patches hiding in inaccessible corners or closed sections.

    After the solution starts to change colour it gets used for the 'first pass' of a mechanically cleaned item, or a first stage chemical clean before going into the first stage bath.

    Finally the filthy green snot gets used for really rusty non-automotive stuff that doesn't really need cleaning but will get cleaned just because I can.

    I don't keep adding citric acid crystals to the filthy green snot.
     
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  17. Ok so I've got some lengths of steel to deriust using hot citric acid , now today I've bought some 110mm waste pipe and fittings as per photo and intend to assemble 3kw immersion element , just ordered a lock nut/flange for the element .
    Obviously the pipe will have a screw cap on one end and be inclined so as to contain the water /citric mix and steel
    Inbuilt thermostat set at whatever say 50, degrees or whatever's optimum ,

    Will be on a 16 amp plug and rcd and will seal up the element cover with silicone sealant to stop any rain ingress

    Anyone see any problems ??

    Cheers mike

    Pic on next post
     
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    • IMG_0601.JPG
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  19. minimutly Member

    Messages:
    781
    Location:
    Pembrokeshire Wales
    Hmmm, the surface area is going to be small, so you can't risk any leaks....
     
  20. There won't be any leaks !there will be about 2.5 metres of pipe fitted to that tee , may even increase to 6" dia on the end so can accommodate larger bits of cource the end cap with element fitted to it will unscrew so could be fitted to a square or rectangular tank for bigger bits .ive some shed doors to make so will cut the steel to size de rust then weld up....
     
    Hopefuldave likes this.
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