Friday, March 9, 2012

How to clean cast iron cookware with electrolysis

While out antique shopping about a week ago, Krissy brought home a nice Wagner #3 cast iron skillet from an antique mall in Delaware, OH.  This particular skillet sat flat with no wobble, and had no immediately visible cracks or chips.  Circa 1935 - 1959.
It looked like this when she brought it home:





As you can see, it had years and years of use.  There is good iron under all that burnt-on food, rust, and failed seasoning.  This #3 will be the subject of our topic in this post.
To start cleaning cast iron with electrolysis, you'll need these items:

1. A plastic tub, filled with water:


2. At least two steel plates to use as the anode in our circuit.  I use diamond plate steel but any scrap steel will do.  DON'T use mesh or steel with holes in it!  Electrolysis works pretty much "line of site" from your cathode (the skillet) to the anode(s). Using metal with holes in it can cause a "ghosting" image of the steel to come out on the cast iron.  I use an 8 gauge wire with metal clamps I got from the hardware store to tie the two anode pieces together.  DO NOT USE ALUMINUM!  It's worth noting here that for the anode, you can use a steel drum or tank.  Completely surrounding the cast iron piece to be cleaned with the anode metal is best.


3.  You're going to need an electrolyte.  Use sodium carbonate at a rate of about a table spoon per gallon of water, maybe less.  Note:  This is NOT baking soda.  Baking soda is sodium bicarbonate.


4. Battery charger.  Only a manual battery charger will do.  An automatic or trickle charger will not work.  I use a 12vdc 15 amp setting but will sometimes set it at 100 amp for a few minutes to get things going.  More than 30 or 40 amps is never really needed.


Now that you have your items collected, you'll need some way to suspend the skillet in the electrolyte solution.  NEVER let the cathode and anode metals touch while the battery charger is on or you may be resetting breakers or buying a new battery charger.  Below you can see that I use a 1/2" piece of EMT and a piece of coat hanger to suspend the skillet, and also conduct the circuit.  Notice that the negative side of the battery charger is on the skillet, or cathode.  Those bubbles you see are hydrogen, use in a well ventilated area!  Your water at first will be clear to cloudy white from the washing soda.  Mine is orange with rust here because I have already done a few skillets with this water.  The solution will last quite a long time and will probably last longer than you can stand to look at it.  If you are using a steel drum you will need to line the pipe with rubber hose, or find another way to isolate the circuit.  You want the electricity to pass through the electrolyte.


 Below are pictures of what the skillet looks like at about 12 hours into the process.  Notice the years of gunk and rust falling off of the pan.  Use a stainless steel scrubbie to remove as much as possible and put it back in the tank.



...and here is the skillet at about 20 hours in...  Take it out and check it once in a while and keep using the stainless steel scrubbie in the sink to remove the gunk and rust until the skillet is free of it.  Go to the hardware store and get a little stainless steel or brass brush to get into the handle and/or the branding.  I also use a knife or small screw driver to clean out the letters or branding.


Once you think you have the skillet free of gunk and rust, put it back into the tank for a few hours.  Once you remove the skillet from the tank, take it to the kitchen and use a product called Bar Keepers Friend and your stainless steel scribbie and brushes to clean it.  You will see that the BKF will get gray fast from the carbon in the iron.  Rinse.  Now, use your dish soap and wash the skillet as you would any other skillet.
Start your oven on 375.  Use paper towels to completely dry the skillet.  Your getting ready to bake it for 20 minutes, failing to remove as much water as possible will cause rust spots on the piece in the oven as the water evaporates.  Your paper towels  will be gray with carbon from the naked metal.  This is fine.  Bake the naked piece for 15-20 minutes using NO seasoning or oil of any kind.  This will completely dry the piece and  open the pores of the metal for the seasoning process.  Below is what the skillet looks like at this stage.


The above skillet is HOT!  It's just below 375 degrees.  Use an oven mitt for this.  Let it cool a bit if you'd like but you want it hot enough to melt the Crisco when you apply it.


Seasoning the skillet
Seasoning the skillet is easy.  Everyone has their own way of how they think it should be done.  I'll stick to the facts and keep it short.  Seasoning has nothing to do with adding spices to the pan.  Seasoning is a process where you are heating "oil" past its smoke point so that it chemically hardens and bonds to the metal.  Use no oil.  Cook with oil all you want but don't use it for seasoning.  You want to use something that is solid at room temperature like Crisco.  With the skillet HOT, start applying a thin layer of Crisco to the pan with a folded square of t-shirt or cotton.  The entire pan.  Top, bottom, handle, everything. The t-shirt will get gray or black from the carbon coming off of the bare metal for the first coat.  Apply a very light coat.  The hot metal will melt the Crisco and soak up what it wants.  Wipe the skillet so it looks wet but don't apply so much that it leaves streaks or you will have streaks permanently bonded in your cast iron.


Once you have your skillet coated, put it in the oven face down for 45 minutes at 375 degrees.  I use the oven mitt the entire time because, well...  It's hot.


There, your 1st coat of seasoning is done.  Easy right?  When the timer goes off after 45 minutes turn the oven off and get the skillet out with the oven mitt and place back on your work surface.  You will notice that the skillet is coated or sealed with a slick, hardened layer of Crisco.  It is not greasy or oily at all.  While the skillet is still hot, add a 2nd coat of Crisco to the entire thing and put it back in the oven at 375 for 45 minutes.  I usually do 3 or 4 coats before the skillet is ready to use.  You can pause between coats if you have to leave or something but bring the skillet up to temperature before applying another coat.

Finished skillet ready for use.  It has a hard, slick, non-oily seasoning that if treated properly, will become as non-stick as Teflon and last a lifetime.


Cook something greasy the first couple of uses...  Burger, or bacon is best. After the skillet is seasoned, never use soap to clean it.  Wipe it out with water, dry, apply a light layer of oil or Crisco to the cook surface and bring the oven up to 350.  If it is very dirty, use a bit of oil and salt to scrub it.  Salt is very abrasive. Or use a green scotch brite pad.  Rinse with water and towel dry.  Once the oven is up to temperature, pop the skillet in to dry face up, turn the oven off and let it cool as you go about your day.


Oil smoke points:
http://www.goodeatsfanpage.com/collectedinfo/oilsmokepoints.htm









31 comments:

  1. I have a couple pans that need this. For the 12v source I have a 20 amp power supply that I use for my radios. I'll let you know how it works.
    Jon.

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  2. Hi, I was wondering. I have a 20 gal. utility can that is galvanized steel, can this be used as the anode to clean my cast iron pan's?
    Thank you for this blog it really help me in my quest to find a way to clean cast iron.

    Karen

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  3. I don't think galvanized should be used. I'm not sure that the zinc will cause too much harm in the way of poison gas (Could be wrong...Google it) but that will rust through in a matter of hours. Use in a well ventilated area.

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  4. Hey Curt,

    I've recently become interested in many of the things my grandparents did, & cast iron cookware is one of them. I already had several small skillets I'd somehow accumulated over the years that I occasionally use for cooking breakfast. I've recently bought a couple nice larger pieces to fry fish.

    I first read about electrolysis on a different website. To experiment & learn how to do it, I used a couple of the smaller skillets, but the results were ... less than expected. Thanks for taking the time to document your methods & thots; I think you've pointed out some of the things I've been doing wrong. Now I need to go find some plate steel instead of using a piece of rebar as I was first told.

    But even after several days, and many hours at 50 amps, I was still left with picking many flakes off, as you described. But even at their best, my skillets only looked about as good as your last picsw of it hanging in your workshop; the skillets are dull, dark and uneven. I'll go find a BKF as you recommended & see if it and steel scrubbies can magically turn mine into the beautiful pans you show sitting on your counter.

    Thanks again for taking the time to share your methods with us!

    joel

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    Replies
    1. You can't use the rebar. You don't just want to conduct electricity. You've got to have complete "line of sight" from the cathode to the anode. If you have a 5" wide skillet, you need a 6" wide metal plate on both sides. Or, completely surround the skillet with stainless bucket/tub. Remember to keep the + & - isolated. Don't use aluminum or galvanized.

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  5. Whoah, that's a thick layer of rust! A washing soda? I would prefer to use an actual rust remover product. Those that are being use for restoring and old vehicles that are bathed with rust and stains. Regards,
    Tanner =)

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    Replies
    1. Tanner,
      Electrolysis is a rust removal PROCESS, not a product. the washing soda creates an electrolytic solution which permits the current to flow from the cathode (item being cleaned) to the anode.
      You know how rust is iron oxide? Well, electrolysis uses electricity to break the bond between the iron and the oxygen, leaving the iron fresh and clean.
      You say you would prefer to use an "actual rust remover product" by which i assume you mean a commercially packaged chemical compound. There are several downsides to this. Many of these products i would not want anywhere near cooking vessels i use, and even the most non-toxic products are quite expensive compared to this method.
      Cheers,
      Daniel

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  6. Hello,

    I hope you are still responding to questions. Thank you for the information you've posted. You note that you can use a steel or stainless steel tank or drum as the anode. Do you mean that, for instance, you could buy a large stock pot to use as the tank itself (in other words, fill the stock pot with the solution and hook the battery charger directly to the pot, and then suspend the cast iron in the middle of the stock pot) or would the stock pot need to sit inside a larger non-conductive container? Also, I've read conflicting accounts about whether using stainless steel produces some sort of toxic by-product. Do you know whether that is true or not?

    Again, thanks so much. I appreciate your taking any time to respond.

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  7. You have the idea down. I would think a stock pot would be too small for some pieces without the metals touching. Look here: http://www.gcica.org/ElectrolysisMethodbyJohnBelden.htm & http://www.rickswoodshopcreations.com/miscellaneous/rust_removal.htm You are doing this outside, right?

    ReplyDelete
    Replies
    1. Thanks for your quick reply. Yes, I plan on doing it outside. I haven't been able to find a watertight steel container large enough, but there are some kitchen grade steel stockpots that would work (80-100 quarts). They're expensive though, and I didn't imagine investing too much just to have a little fun in the back yard with some old cast iron. I actually saw the website you linked to, which gave me the idea of using a steel container as the anode. It just seems simpler, but I was a little concerned about having the pot sitting out with a positive charge going to it, even if it is only 12v.

      Right now, I have my dad looking for an extra 55 gallon steel drum where he works. That size seems a little bit big, though, considering it sounds like you get the most efficient operation if the pan and the anode are as close together as possible without touching.

      So, I'm not sure right now what the best solution is. I've also seen some washtubs, but they are mostly all galvanized steel and also too short (about 11"). I'm going to keep my eyes open and maybe I'll come across something.

      Thanks for the information you provided on your site, and thanks again for your reply.

      Delete
    2. The gcica.org link has changed to http://www.gcica.org/forum/showthread.php/155-Cleaning-Cast-Iron-using-Electrolysis-By-John-Belden?highlight=John+Belden

      Delete
  8. Why does a trickle charger not work - does it just take lot more time?

    ReplyDelete
    Replies
    1. By trickle charger I mean battery tender. The very small ones just don't put out enough (.75A) amperage. Also, those have the ability to detect whether or not there is a short, which it will then switch off.

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  9. Hello.
    I'm trying to strip an old Griswold 7 but the only battery charger I have is an automatic that refuses to put out more than 2 amps. I'm willing to leave it in for a longer time if that's all the low-power system will need, but I can't tell if this will work. Do you know if I can still get a thorough stripping this way?
    Thanks!

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  10. I want to clean a 20 gal cast iron pot. Can I use the same method? does sthe cast iron need to be suspended in a plastic tub or can it sit in the tub?

    ReplyDelete
    Replies
    1. As long as it's a plastic tub that you are placing it in, yes. Just make sure that it is totally covered with water, and the pot doesn't touch the metal. It you can post before and after pictures, please do so.

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    2. As long as it's a plastic tub that you are placing it in, yes. Just make sure that it is totally covered with water, and the pot doesn't touch the metal. It you can post before and after pictures, please do so.

      Delete
  11. So, does it matter if the charger is more than 40A?

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    Replies
    1. I suppose not. It won't do you much good though that high.

      Delete
  12. Can u simply use a plastic 5 gallon bucket w 2 iron rods one clamped on each side (one side POS and the other neg and then use a metal pipe or thread all to lay across the top to suspend the piece to be cleaned from??

    ReplyDelete
    Replies
    1. 5 gallon bucket would not leave enough room for a skillet I wouldn't think. I do have a square kitty litter bucket that I use sometimes for smaller items. No on the rods. You don't just want to conduct electricity. You've got to have complete "line of sight" from the cathode to the anode. If you have a 5" wide skillet, you need a 6" wide metal plate on both sides. Or, completely surround the skillet with stainless bucket. Remember to keep the + & - isolated.

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  13. Whats the best charger I've already burned through 2 of them?

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    Replies
    1. Any manual charger that you see at flea markets. It can't be "automatic" or "trickle". If you're burning through them, you've got something wrong in the circuit. Or, your causing a dead short while the charger is on. Which would be easy to do since you've got the two metals so close. You want the cathode and anode isolated except for the electricity flowing through the electrolyte.

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    2. Schumacher makes some reasonably priced manual chargers that are good for rust removal by electrolysis. http://davehallier.com/best-charger-for-rust-removal-by-electrolysis

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  14. I noticed my steel cathodes after a weeks use have corroded will that happen if i use a stainless steel tank as the cathode?

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    Replies
    1. The plate steel anode's will become rusted. Just use a wire brush and clean them after each use. I believe the stainless will last longer but all anode's will wear out eventually.

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  15. Never use brass to clean your cast iron with. It will leave a brass color in your cast iron. Learned that the hard way.
    Other than that, good blog!

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  16. Does the "sacrificial" metal have to be steel or can aluminum be used? I have access to aluminum for free as opposed to paying for steel.

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    Replies
    1. Everything I've read on this and other posts indicate to use steel or stainless steel. Never, and I mean NEVER use aluminum.

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  17. Have been learning cast iron electrolysis using an assortment of pans-on-hand and having success . . . until today.

    We have been using the deep cycle on a 10 amp automatic battery charger and were able to do so without the addition of the suggested “work around” of a 12 volt battery in between charger and bath.

    Today, we decided to try cleaning a modestly encrusted, gate marked, thin (suggesting old) pan. Followed usual process, plugged charger in and needle jumped to 10+ amps then dropped immediately to 0, suggesting it thought the “battery is fully charged.”

    Any idea why other pans would not do this? Or why this one does? Subsequently tried other pans with success. Have confirmed the pan is magnetic. Have confirmed the anode and cathode are not touching. Have reached frustration level.

    Any thoughts?

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