Hi folks! Thought y'all might want to see my new zap tank for electrolytic rust removal! I've been wanting to build an electrolysis tank for years, and after seeing their prevalence on this forum, I finally took the time to learn how they work, scoured the internet for different designs, incorporated a couple of my own ideas, and put this fella together. My grandfather's old Exide-brand battery charger is absolutely ancient and needs to be rehabbed, but it always works and I've never had a problem with it. It must be at least forty years old, and probably a decade or two more than that. I'll be fixing it up this winter, but always take proper safety measures in the meantime, as discussed later in this post. The most exotic tool used was an electric drill, so anyone with the most basic of tools could build this. Anyway, meet Frank the Zappa Tank!!! Siiiiiiiiiiiiiiigh... Kübel! I'm not really a Zappa fan, but sometimes the jokes just write themselves, you know? Here's a cheap beer can for size reference next to the 30-something gallon tub. It's a very cheap plastic storage tub, and I don't really expect it to last more than a year or two, if that. Water is very heavy and puts a lot of stress on the tub. In the future, I'll use something stronger, as I don't really like the idea of it cracking and water rushing towards a battery charger. Especially if I'm standing nearby. I liked the positive anode grid design I've seen kicking around the internet, so decided to go with that. There are twelve 1" flat stock mild-steel anodes attached to the tub, which are linked together with 10-gauge wire. The washers help to decrease the stress on the cheap plastic tub, and I used a bunch of hardware I had lying around to connect the anodes to the tub and to the connecting wires. I went a bit overboard with the hardware, but everything is nice and tight to complete the electrical circuit. You'll notice the gap between the two anodes on this side, and that they are not linked in a complete circle. I forgot the reasoning behind it, but I read somewhere not to do that, so there's that for what it's worth. A metal bracket mounted on the tub serves to connect the anode grid to the positive cable from the battery charger. It is clearly labeled to reduce the chance of getting mixed up and accidentally attaching the negative cable. Though electrolysis is a fairly benign process and I'm probably being overly cautious, should I need to quickly disconnect power to the zap tank, the positive cable can easily be knocked off of the bracket by hitting it with something non-conductive, like a piece of wood. I kept a 2x4 board nearby just in case. Here's a picture of the anodes. I put pieces of plastic mesh over each anode as a barrier to prevent the negatively charged pieces I'm de-rusting from accidentally coming in contact with the positively-charged anodes. One anode was left without the plastic mesh to test if the mesh was an impediment to the process, as I was concerned that the mesh may be a bit too fine. I found that all anodes had roughly the same amount of rust on them when I finished and that the mesh does not inhibit the rust removal process, so I will continue to use the mesh as a protective barrier in the future. I do need to attach them better to the anode though so that the bottom part will not float up in the tank. I figure just a rubber band should suffice. Notice that the anodes are standing away from the side of the tub. I don't quite understand why, but I read somewhere that with a big enough tank, line-of-sight between the positive and negative anodes is no longer as big of an issue, as the entire tank becomes charged. To increase surface area of the positive anodes, I made sure to position them away from the wall of the tank to expose the back of the anode, and found that all the positive anodes ended up with roughly the same amount of rust on either side. In my experience, with this particular tank and this particular project, I did not need to concern myself as much with line-of-sight travel for the rust particles. I'm a hobbyist metalworker, so woodworkers, please don't judge this too harshly as this is not my medium, but I put together this little contraption to go over the tub to suspend the pieces from. It is very stable when the tank is filled with water. Wood is a poor conductor, and though I was a little scared to touch it the first time, it allows me to lift the pieces out to check on them while the tank is running. I gave it a coat of primer and paint to match the tub. (Cheap beer for size reference.) Here it is sitting on the tub. When filled with water, the inner braces fit very snugly against the tub, and the outer braces make perfect handles to pick it up. I took a milk jug and poured one gallon at a time into the tank, marking the water line at five gallon intervals. This way, each time I want to change the solution, I can fill the tank up to the desired level and know how many tablespoons of washing soda to put in. Twenty gallons is the maximum amount I would comfortably put in this tank without worrying about it breaking from the outward pressure of the water. I took some more 10-gauge wire and put this together to attach the negative cable from the battery charger to the piece I want to de-rust. I'd read here on Classic Camp Stoves and elsewhere that you can quickly ruin your charger's leads if you put them directly in the tank, so this is a cheap, easily reproduced, sacrificial lead. You connect your charger's negative cable to the bolt, and you have two alligator clips to attach to your piece. I figured this would be good for Optimus 111 and other stove cases to make sure that both case halves get a good connection. I have made two of these cable assemblies in case the tank eats one of them. With a bit of finagling, they can both be gripped comfortably by the negative cable from the charger, so I can de-rust up to four pieces at a time without having to link them together with wire or something inside the tank. That means two cases at one time! Here is what the positive and negative connections look like. Before actually using the tank, I broke out the electrical tape and covered the exposed wiring. This winter, I will fully tear down that old battery charger, clean everything, and replace those ancient leads. In the meantime, I do not leave it unsupervised, I have three different ways to shut the power off to it from various distances (including behind a brick wall), and I have a fire extinguisher and water hose nearby in case of fire. I used to be a firefighter, and though I've never had an issue with this old charger before, I certainly see the risk, and take cautious measures. It's very well-built and is an absolute tank of a charger though, and I wouldn't be surprised if this thing chugs along for another 40+ years. It's definitely worth restoring. I've never tried electrolysis before, so I didn't want to test it on one of my stoves first, so I found these old horseshoes knocking about. Here you can see them suspended from the wooden thingy. And here they are sitting in the active zap tank, shortly after putting the washing soda in. There's roughly 17 gallons of water, so I put in 17 tablespoons of washing soda. Here you can see the hydrogen bubbles pouring off of the horseshoe. It works great! I ran it for about 12 hours, and two of the horseshoes were completely de-rusted. The third one needed a lot more time in the tank, but this was just a test, so I didn't want to spend any more time supervising that charger while doing yard work. I'd read about flash rusting, so before pulling the horseshoes out, I preheated the oven to 300 degrees or so on the broil setting so that I could put them in there and dry the solution off quickly. I pulled them out of the solution (I did not rinse them in water) and quickly put them in the oven. Unfortunately, after five minutes or so, when I opened the oven to check on them, they had all flash-rusted over and looked almost as bad as when I put them in. What did I do wrong? Did I need to wash the solution off first? The anodes were a great success though, and though I could probably wait another cycle or two, I will just grind off that rust on the bench grinder and have a clean anode for the next time. Overall, the tank runs beautifully and pulled the rust right off in a short period of time, but I need to figure out how to avoid flash rusting before I try this on one of my stove cases. Does anyone have any advice on how to avoid flash rust? It's rugby season too, and though I'm currently out with a cervical spinal injury and not playing, I'm still traveling with my team to the matches, so I will need to find a free weekend when I can supervise that old charger before I try a stove case too. Well, thanks for reading, I hope I didn't bore y'all too much, and hopefully there's a bit of useful information for someone in this post! Happy stoving! -Pinky
excellent work!! and very well constructed i will read this slowly and try and digest the information i have been thinking about building a tank like this for a while thanks for sharing the information great respect Blaze
Very inspiring job. While thinking about it-the easiest way to make this last longer, and to make it stronger right now, is to buy one or two more plastic tubs. Cheap. They nest right? Just nest the wired one into one or two more on the bottom. Cut them to just under the bolts, or get a size that is that height already. Then, support the bottom hollow spaces with some cheap urethane foam chips such as are used to pad packages, or get the kind out of the spray can sold for sealing window frames.Fill the spaces so the tub bottoms compress the filler material solidly. I once made a tank for transporting live salmon fry samples to the lab. We used three of the big cheap rubbermaid 20 gallon tubs, nested together. The end result was strong enough to hold together while lifted into and out of a truck bed. We learned the hard, wet way to support the hollow space under the bottoms of the nested tubs. Your frame for supporting things also helps the strength of the tub, which is quite floppy full of water. Thinking out loud: Do the iron bars hang, or are they bolted? Having them out from the sides is a good idea for efficiency. Do they need to be bolted, or could they just hang in the solution? Would the electrical contact be good enough in this application if they hung? Would the convenience of quickly removing them for cleaning be worth it? Wing nuts instead, or would they rust in place? As to flash rusting, I have rinsed in fresh water immediately-a tub right next to the zap tank. A quick dunk, then a careful heat up with a propane torch. This dries things quickly. I have sometimes scrubbed things with one of those dish scrub pads when they needed it, then rinsed again and heated again. If I am really efficient, I spray paint while it is slightly hot. This lets the paint adhere well and start to cure without runs. Just did a coleman tank that way.
Thanks Blaze! And sorry for the length! It's a bit word-heavy, but I figured anyone actually wanting to build one would want to know all that they could about it. Give me a holler if you have any questions, though I'm sure there are many, many others on this forum with much more knowledge about the process than me! There are a lot of great web pages out there detailing it too. Just Google "Electrolytic rust removal", and you'll find a plethora of information. I'm rather annoyed about the flash rusting, but other than that, it all worked great! And XGK81, I'll give that nesting idea a shot! Thanks a million!
Oh, and XGK81, they are bolted in. I'm not sure whether electrical contact would be strong enough or not if they hung, but as long as they have current, that's all that really matters. I thought about using sheet or expanded metal, but I figured that if I wanted to keep reusing the same anodes for a while, a relatively thin bar of flat stock would be the easiest and quickest thing to clean up on a bench grinder. I wanted to use wing nuts, but didn't have any on hand, so bolts it was! As long as the solution doesn't splash around too much, I don't see why wingnuts would rust though. I had only a few rust spots on my hardware where water must have dribbled. If they did, you could just grip the wingnuts with some pliers and turn them loose. I don't particularly mind unbolting them though. I enjoy tinkering, and honestly, I'm not going to be using this thing all that often. I'll definitely try the extra water tank and propane torch for my next project! Thanks for all of the great ideas!
Hi Pinky, This is the Rolls-Royce of electrolysis tubs! Well designed, and well built. A thought occurred to me that you might build the bracket for suspending the de-rusted items out of metal, which will provide the electrical connection. As for preventing flash rusting, what I do is rinse the cleaned part in hot water under the tap, and wipe dry. If I don't paint immediately I give it a light spray of WD40 (which I remove with alcohol or gasoline before painting). Yonadav
Nice job and well thought out. Mine consists of a 4 gallon plastic bucket and an old lawnmower blade. As already stated, a quick rinse in fresh water and then wipe dry should minimize the flash rusting. I think you will find that the flash rust looks worse than it is and a quick rub down with some steel wool will make the surface look great. The clips for the negative terminal should be safe, even if they are in the bath. The positive one however will quickly be chewed up, so that is the one to be careful about. One more thing. Even with the wood frame, I'd really recommend turning off the power before checking its progress -- is there any reason not to?
Excellent job, Pinky! (I'm emailing your post to myself for future reference and to add into my personal "Museum of Master Fettling".) Cheers, Gary (the old "Dancing Fool")
Hi Pinky, That is a great set-up - thanks for sharing. One modification I might make if I was recreating this set up is to suspend a piece of steel rodding underneath your wooden bar. You could then just suspend workpieces at any point using wire and have a simple point of connection for the lead from the charger. In fact, using that method yoiu could make a permanent connection from the charger, leaving the other as the emergency "knock-off" disconnect meaning you'd also never be at risk of mixing up the connections. Cheers, Graham.
Excellent thing! Much more involved than my one (a piece of 1/4" plate in the bottom of a square bucket) I like the 'whole charged up tank' idea for big cook ups. Bravo!
Thanks for all the great advice, ideas, and compliments gang! Now I'll be able to avoid flash rusting for the next project! I guess I missed the rinsing part while researching the process. Sounds like the negative electrodes are the weak spot of the design, huh? After reading through all of your great suggestions and thinking about the project's current components, the materials I have on hand, and the sweat equity involved, this is what I came up with: I was thinking I would take another 3 foot section of flat stock steel, drill a couple of holes, and bolt it to the wooden support. It would sit directly between the currently drilled holes in the wooden support, and would overlap the edge by a few inches on one end, making a perfect perch to attach the negative electrode. I could then shorten my current alligator clip negative leads and hang them from the bolts that attach the steel stock to the wooden support. I'd prefer to use the alligator clips to make the electrical connection, since I have little doubt that they make good contact. I would then hang the piece to be de-rusted from the wooden support. What do y'all think? This would be an easy way to incorporate the nucleus of your suggestions, it would clean up the big mess of wires, plus it would take just 20 minutes to do. It's all a bit overboard for just an electrolysis tank, but it's been a fun project! And Itchy, you're right! I'll quit messing with the tank while it's running! Thanks again for all of the great advice and support y'all!
It looks good to me. I wouldn't worry about it being over engineered. If you've got the space for a permanent set-up why not make it as easy to use as possible? One final suggestion while you've got the wood saw out - if you're worried about the stability of the plastic tub when full of water it should be a simple matter to make a wooden cradle to support the sides and relieve the pressure. Cheers, Graham.
Well, it's easy to sit on the sideline and give fancy advice, while you're the one doing the work. So here's another idea: How about adding a drain valve? Maybe even with a hose that goes to the drain? Yonadav
Great tank! I made one but not nearly as well thought out as yours. Time to revise mine. I like your new idea or a flat bar along the two by four as the negative anode. I had one idea perhaps you should drill 5 of six hole in the bar and insert bolts in the holes facing upwards so the head of the bolt is between the two by four and the bar. Then you can easily attach you negative leads with wing nuts along the bar depending on what you are cleaning.
Thanks fellas! At this point, I think I'll try xgk81 's suggestion to buy another cheap tub and nest them with some foam underneath to give it a bit more rigidity. It may be a week or two before I can do the upgrades, but I'll certainly post pictures when they occur! Yonadav, a drain would be nice, but you'd have to position it well above the muck that collects at the bottom of the tank to keep it from clogging. I just bailed it out with a small bucket until I could tip it over. I can't remember if I read it here on CCS or somewhere else, but someone proposed using a rolling trash bin for a tank, which sounds fantastic! Big tough plastic, maneuverable even under a heavy load, plenty of space. Perfect! I certainly have no need for something like that, but if it were to be used frequently, perhaps for a business or something, that sounds ideal!
