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rust removal?

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  • rust removal?

    I know there are lots of ways to remove rust. But it's a never-ending problem, so I still think about it sometimes. Lately I've come to wonder if it might be practical to apply hot carbon monoxide to a rusty part, the theory being that the oxygen-hungry CO will strip oxygen away from the oxidized steel, converting rusty steel to less rusty steel and converting CO to CO2. One way I can think of to do this would be to fire up an oxyfuel torch and run it rich; i.e. starve the flame of oxygen. I've actually tried this on a piece of rusty scrap and it appears to work. When I pass the flame over an area of flaky rust what is left behind is usually black steel.

    One possible application would be to derust the inside of a cast iron pot with a lid. Put a bunch of hot coals into the pot and put the lid on. Some smoke would leak out, but basically the coals would convert to charcoal but the atmosphere inside the pot would be CO-rich so you'd think it would strip the rust from the inside of the pot. This I have not tried.

    It wouldn't be practical to run an oxyfuel torch over very large of a surface area before the time and fuel needed would exceed the value added. Hence my question: can you think of a practical way to generate a lot of hot carbon monoxide and a way to deliver that to a rusty part cheaply?


  • #2
    Gonna sound really stupid, but auto exhaust?

    My main concern would be how to keep what area/volume of space you were introducing the carbon monoxide into sealed well enough so you or others were not effected.
    Also not sure how relatively efficient it would be in terms of value added...I just instantly had visions of all those service stations with those exhaust hoses hooked to cars and run outside...I guess how long it would stay "hot" quickly becomes a concern for your particular application as well.


    • #3
      I don't know too much about chemistry, but I think
      you need to add some energy in a big way to reverse
      entropy there. Like a blast furnace maybe.



      • #4
        Sounds expensive and dangerous.

        Electrolytic rust removal is dirt cheap, safe and reasonably fast.
        It can be a bit messy (far less so if you use graphite sacrificial anodes) but all in all it's hard to beat.
        It's about the only method used by museum curators to preserve iron artifacts.


        • #5
          Sound like a great way to kill yourself (CO poisoning).

          Without an enclosure and inert gas environment, how do you keep oxygen in the air from the area?


          • #6
            Back in the late 1980s there were several papers on archaeological iron conservation using low pressure hydrogen plasma. I've been out of the business so have not kept up with developments.
            Not that I would recommend this for a home shop!
            Mark (Museum Conservator, retired)
            What you say & what people hear is not always the same thing.