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My first Electrolysis

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  • My first Electrolysis

    My foot pedal for the Trinco Media Blaster froze up. No surprise, it was pretty rusted. Since I'm in the process of moving equipment around the garage the blaster was out of commission. Looks like it's time to try electrolysis.

    In the beginning:


    It was very ugly:




    The 5 gal bucket with 4 gals of water and 4 Tbls of washing soda. 4 sticks of rebar with copper wire attached to each piece. Electrolysis, from what I've read is line of sight, who am I to argue.
    Rob

  • #2
    after 24 hours: not so impressed. the light rust came off and was very smooth. the heavier rust probably needed another 24 hrs. too bad, since it wasn't fully submerged, I turned it over w/o adding add'l water of soda. and I didn't clean off the rebar.


    this is > I turned over the pedal and another 24hrs in the nasty gunk. still pretty bad, but at least all the hinges now work. So I took it out, sprayed it down, and ran a grinder over it.


    hmmm, not too bad, just a light grinding.


    and > I sprayed on some permatex rust inhibitor (nobody carries POR-15 around here)
    Rob

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    • #3
      Primed and painted w/dupli-color: works for me!



      What did I learn?
      1) I need a bigger bucket
      2) when there is rust inside of a part, rig up some rebar on the outside and the inside)
      3) clean the rebar, change water, add more soda after 12 hours (especially on heavily rusted parts)
      4) Let it do its' work by letting stay in the mixture for longer periods of time.
      5) go to my buddies house to use his media blaster when mine is down.
      Rob

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      • #4
        I think I'd have just made a new one. :-)
        ...lew...

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        • #5
          Originally posted by rmuell01
          What did I learn?
          1) I need a bigger bucket
          2) when there is rust inside of a part, rig up some rebar on the outside and the inside)
          3) clean the rebar, change water, add more soda after 12 hours (especially on heavily rusted parts)
          4) Let it do its' work by letting stay in the mixture for longer periods of time.
          5) go to my buddies house to use his media blaster when mine is down.
          1.) Yup, works best when the entire part is submerged.

          2.) If the inside is narrow (ie passage, pipe, etc.) use a cloth wrapped around a piece of rebar of chain. The cloth will keep it from shorting out.

          3.) I leave the part in for anywhere from 3 days to 3 weeks depending. Each day, pull the rebar and the part in question. Scrape the crud off of the rebar, wash off the parts (rinse with garden hose), submerge again. If you remember to clean everything every 12-24 hours, it doesn't take too long. I usually forget...that's why the "up to 3 weeks" part mentioned above!!

          4.) Yes, let it cook, but it also needs to be cleaned off as rust/paint/grease/grime gets loose.

          5.) Well, that's no fun!

          Andrew

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          • #6
            You can cover an electrode in plastic window screen material and place it inside an item to derust its interior.

            Shoot! Andrew D beat me to it.

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            • #7
              Maybe more power.I was using my 6 amp battery charger and found 6/12/24 volt charger with higher amp output and I have had plane bodies warm enough the water was starting to steam.

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              • #8
                Hello,

                I'm curious about the polarity that you used in your electrolysis with washing soda. Articles that I've read, state that the negative is connected to the part in the mix. I recently did some chrome removal in electrolysis with a cup of muriatic acid in 4 gallons of water and used positive on the part based on several articles that I read.

                I've looked on the internet and can't find the reason for the oppositve polatrity unless it is due to the difference between the alkaline washing soda and the muriatic acid.

                The chrome was removed from a Harley part in less than an hour. I used a the 6 volt 6 amp setting on my 6/12 battery charger. I first tried 12 volts, 2 amps but it kept opening the internal breaker in the charger. I suspect that there was too much current on 12 volts. In any case, 6 volts was fine. It removed the chrome down to the nickel, which was what I wanted since I was able to bead blast the nickel sufficiently for powder coating preparation.

                I'd provide pictures but I don't want to steal your thread. It looks like you did well. I am curious about the difference in polarities in any case. For the record, I tried negative on the Harley part and it didn't do anything.
                Last edited by gnm109; 05-03-2012, 10:22 PM.

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                • #9
                  The difference in polarity is because of the pH of the liquid. Acid wants one polarity and base wants the other. I can never remember which is which, and always have to look it up.

                  Pops

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                  • #10
                    Originally posted by armedandsafe
                    The difference in polarity is because of the pH of the liquid. Acid wants one polarity and base wants the other. I can never remember which is which, and always have to look it up.

                    Pops

                    Great! Thanks. I'm certain that the part takes positive in acid chrome plating removal so it would have to be negative on the part for electrolytic rust removal with waching soda.

                    I wonder if acid could be used to remove rust......?

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                    • #11
                      We often use vinegar to remove gun bluing, which is a form of rust. I've never used an electrolosys process for that, however.

                      Pops

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                      • #12
                        Re the polarity:

                        A bit of basic electrochemistry, very over-simplified...

                        Metal ions are generally positively charged, so get attracted to the negative electrode - in stripping the negative is the rebar or whatever, so the chromium ions (in your example) first bind with the chlorine (negative) ions in the muriatic acid freeing up the acid's hydrogen which bubbles off the workpiece, then get attracted to the negative electrode where the chlorine's liberated to take another round trip.

                        When electrolytically derusting, the workpiece is the negative and the rebar/whatever positive - the rust is composed of iron (positive ions) and oxygen (negative), so the oxygen's attracted to the positive electrode (and oxidises it, making it go rusty), the iron's on the negative terminal and held there by the negative charge. The washing soda in the solution doesn't really take part in the reaction, it's there mostly to make the water conductive so the current can flow through!

                        Please be aware that if the chrome-stripping solution turns yellow it's a sign that hexavalent chromium is present in the solution - this is **VERY** nasty stuff, carcinogenic, a nerve and liver toxin even in small/trace amounts... I could go on
                        IF so, before disposal add some sulphuric (battery) acid until the yellow colour disappears and you'll have made it a lot safer - either way, the resulting solution is technically a hazardous chemical and needs proper disposal, usually at a licenced facility (ouch, spendy!)

                        Please *don't* use stainless as the positive in a derusting setup either - same problem, although it looks like the electrode isn't being eaten away and stays relatively un-encrusted, the chromium is entering solution as the hexavalent form (which is why the solution would turn yellow...)

                        I've had good results using graphite as an electrode for anodising aluminium, perhaps it would work well for de-rusting?

                        Dave H. (the other one)
                        Rules are for the obedience of fools, and the guidance of wise men.

                        Holbrook Model C Number 13 lathe, Testa 2U universal mill, bikes and tools

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                        • #13
                          Thanks, Dave. It has been so long since I have worked at any electolysis or plating, I could't remember enough about ions' wanderings to be comfortable posting the internal happenings.

                          Pops

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                          • #14
                            Sounds to me like your electrolysis cleanup is taking way too long. I suggest the process would be much faster with an appropriately larger piece of sacrificial metal for the anode than the rebar rods. I typically use worn out saw blades or scrap sheet metal. Think current density limits and you will understand the value of larger surface area. I use a cup per gallon of washing soda too. My tank usually runs at 14 volts and self limits at around 2 to 4 amps of current from my power supply. An hour or two would be plenty in such a setup, although I often pull it out early and wipe or scrape off any severe rust build up under running water and then put it in to finish.

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                            • #15
                              Do a Youtube search on molasses rust removal. Seems to work well.
                              Dan

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