Backyard DIY Electrolysis for Rust Removal on Cast Iron and Tools

I'll bet everyone reading this has a secret stash of rusty something-or-other; Granny's Dutch oven, tools left in the rain, a cool garage sale find. If only there was some quick and easy way to return the metal to bright and shiny...

There is. Here's a sweat-free, pain-free method of removing every particle of rust from your rusty junk- using the miracle of electrolysis and some random stuff you probably already have laying around.

Step 1: Equipment for Your Miracle

Here's what you need:

An automotive battery charger, 10 amps or bigger. A smaller trickle charger will work, but it might take weeks instead of hours to remove all the rust. One with a built-in ammeter is best, so you can tell when you have a good connection.

A plastic tub, bucket or container, big enough to suspend the rusty article completely free of the sides and bottom; you want the solution to circulate freely. You can also line a cardboard box or basket with plastic to hold the solution- anything will work if its sturdy enough and can be lined in plastic

Arm & Hammer WASHING Soda (not baking soda). You'll find this in the laundry detergent aisle.

Steel for the anode- rod, sheet, bar, whatever you have handy or can buy cheap. Old metal junction boxes, pieces of rebar, literally whatever you have. The more surface area the better.

A non-conductive rod to suspend the rusty article from. I used a piece of CPVC pipe, but wood is good too.

Some wire, any kind

Step 2: Safety First

Do this outside, please.

You will be generating some hydrogen gas and you don't want any explosions in the garage.

Step 1) Fill the plastic container with a measured amount of water- when filled, you will add 1 Tablespoon of washing soda per gallon of water; stir to dissolve. Tip- make the last gallon you put into the tub HOT water, you can dissolve ALL the washing soda in the hot water and you'll get a fast, thorough dissolve.

Step 2) Place the non-conductive rod across the top of the solution container, and wire your rusty article to is so your article hangs completely submerged, but not touching the sides or bottom.

Step 3) Place your anode steel in the solution (the anode can touch the sides and bottom, and it can stick out of the solution too) but make sure it is AT LEAST 2” from your rusty article. Any closer and you will pull too much current on your battery charger and might damage it.

You can use more than one anode, such as multiple pieces of rebar on different sides of the rusty article, as long as all the anodes are electrically connected, i.e. wired together. Using more than one anode speeds up the electrolysis, and you won't have to move and turn your rusty piece during the process, but use whatever is easiest for you. You can also do more than one rusty article at a time, as long as- you guessed it- they are electrically connected to one another and nothing touches.

Step 4) Connect the BLACK clamp of the battery charger to the rusty article, and the RED clamp to the steel anode, and turn on the charger. You can use an extra alligator clip jumper if that makes a better connection to the piece than your regular clamp.

Turn the battery charger on and check the ammeter to see whether or not its “charging”- if not, you may have to scrape a clean spot in the rust so you make a good electrical connection.

Let 'er rip!

Step 3: Making the Magic

You will see bubbles start to form almost immediately, and an ugly rusty sludge will collect on the surface- all normal.

Every so often, turn off the charger and lift out your rusty piece to inspect how the rust removal is going; take this opportunity to turn or invert the piece if you are using a single anode, to make sure all parts are getting blasted.

The length of time you will have to leave your rusty article will depend on how rusty it was and the amperage of your charger. It will probably take a few hours, maybe overnight to totally remove the rust. It won't hurt anything if the charger continues to run, but it won't help either.

You can dump your rusty, sludgy water on the garden, or save it for your next rust-removal project. * note; if you used a stainless steel anode, you may have generated some semi-toxic byproducts; better to not dump this down the storm drain or into your vegetable garden.*

Step 4: Yes, You ARE a Genius;

When you remove your work piece the final time from the solution, you will have noticed that instead of rust, your piece is now covered in a sooty black oxidation layer. The easiest way I've discovered to remove this is with 3M Brand GRAY Finishing Pads, available at Lowe's in the sandpaper aisle, but if you need a more polished surface, you may have to work with the softer white scrubbies. It only takes a few minutes to remove the black stuff.

And voila, you have resurrected Granny's Dutch oven with the expenditure of just a little bit of money and the time it took your cauldron to do it's bubbly electrolysis magic.

Take a bow!

Step 6:

<p>Sir, YOU are a genius. Great how-to, thanks!</p>
Hi, I noticed that you said to use at least a 10 amp battery charger, but never mentioned the voltage. Then in your picture, your charger appears to be putting out less than 2 amps. 2 amps at 5v would be a cell phone charger. 2 amps at 36v is a whole other story - the first is 10 watts and the second is 72 watts. I have a bench power supply that can provide a steady current anywhere from 0-30v at 0-5amps. Where would I set it?
<p>OsterAC,</p><p>A battery charger is always 12Volt., with 2Amp and 10Amp output respectively. There are smaller Battery Charges also. But we are speaking about Battery Charger related to the procedure, described by this Auther.</p><p>So, coming back to your curiosity, please assume, that the Author i.e.: Cheese Queen was using a 12 Volt battery Charger @ 10Amps.</p><p>Please thank the Author as most people have already done.</p><p>Thank you, OsterAC</p>
<p>Maybe you should say, or have said, a &quot;car&quot; battery charger. Battery chargers are NOT always 12 volts. I have plenty of batteries, even some SLA ones that are less than 12 volts. </p><p> Your method of removing rust certainly is interesting, but I prefer a soft wire wheel on a bench grinder or drill. A lot faster, less trouble and less mess. </p>
<p>It is still cool and a grinder probably removes more material, but often you get a shiny surface with less pits. And unless the author edited the article, they did say: </p><p><strong>An automotive battery charger</strong>, 10 amps or bigger.</p>
<p>and you breathe the rusty dust... rust dust!!!</p>
<p>Well, duh, that's what dust masks are for. But to keep from breathing harmful chemical fumes, a more expensive, respirator is required with filters rated to filter either general fumes or specific fumes, and only for specific periods of total time. I worked at Olin Chemicals years ago and we all had to carry an emergency respirator that was good for only a few minutes, until one could get to safety. And, it was designed specifically for Chlorine gas. </p>
<p>That works as well but with the chemical bucket method, you can work on several pieces at once. Although removing the black soot afterward must be done indivdually by hand. Hmmm, It may be a wash.</p>
<p>As I read the article I also looked at the pictures and saw that it was a car battery charge, and zoomed in to see it is set at 12 volt.</p>
<p>A wire wheel (or sandpaper, or any abrasive) is only good for an exposed rusty exterior. The electrolyte works where a wire wheel cannot reach.</p>
<p>exactly, <a href="https://www.instructables.com/member/osterac" rel="nofollow">osterac good point! my shop charger will charge at presets of 6, 12, 18, 24, 30, 32, 36 and 48v and amperage up to 160 in boost mode <br></a></p><p><a href="https://www.instructables.com/member/osterac" rel="nofollow"> <br></a></p>
<p>I have used this technique for years, but in a slightly different fashion...</p><p>I use lye in the water to form the electrolyte, and a large (approximately 40 gallon) plastic barrel, and a 36 volt golf cart battery charger. Same process, just on a larger scale. Any water soluble substance that allows the electricity to flow can be used to form the electrolyte, but some can be quite toxic. The washing soda idea is something I am going to try. Lye can be hard to find these days.</p><p>Care needs to be taken with the lye, but the solution is not strong and I have had no problems with chemical burns. Of course, whenever I come in contact with the electrolyte I wash my hands immediately. And don't wear any clothes doing this that you are fond of. And take off any metal you wear, rings, watches, etc.</p><p>Rebar works great as an anode, but the rust flakes soon coat the bar and reduce the effectiveness of the process. Depending on the size of the project - say, like the cargo rack from a 4-wheeler - you may need to replace the anode more than once. I keep a few pieces of rebar handy, so I can replace one and clean up the other. I hose the crusty used anode off thoroughly - rubber gloves help, remember the lye - and let it dry. Once dry, a wire wheel on a bench grinder (or drill) makes short work of producing a clean &quot;new&quot; anode. You will be generating a significant cloud of red dust, I wear a simple face mask. My shed isn't exactly &quot;tight&quot; - more like a small pole barn - so I do this indoors, but it's best done outside.</p><p>You will be surprised at how fast the rebar will erode. Apparently, the iron rust being dissolved by the electrolysis process takes iron from the anode to form the rusty fuzz on the rebar. I'm sure a chemist out there will have something to say about that. Of course, I'm using about 40 volts and several amps... </p><p>The reason for hooking the red positive clamp from the battery charger to the anode stems from the fact that electricity actually flows from the negative terminal to the positive. Hook this up backwards and you will end up with a shiny piece of rebar and granny's dutch oven will be coated with rusty flakes!</p><p>By the way, protect the cleaned metal surface asap. This electrolysis process leaves elemental iron exposed to the air and it will start to rust faster than you might believe. Also, this process does NOT remove paint. Anywhere that the paint has separated from the metal surface will bubble up and is easily removed, but you need to plan on removing paint if you are going after that &quot;new&quot; look. Speaking of looking &quot;new&quot;... this process does not remove or fill in rust pits in the metal. It only removes the actual rust. </p><p>A final note: I drain the old electrolyte solution on the ground. It's a weak base, further weakened by the water used to rinse the tub. The weeds behind my shed seem to thrive on the stuff. And I only do this a few times a year - once you get past the experimental stage where you want to &quot;derust&quot; everything in sight, you find that you get interested in other stuff!</p>
If substituting lye for the washing soda, what mix ratio would you use?
<p>Frankly, I never bothered to measure it. A small container of lye - 6 or 8 fluid ounce size in the 40 gallon tank works for me. Remember, the purpose of the lye is not to do any actual cleaning, it is there to create the electrolyte solution that allows the current to flow in the water. The lye functions as a catalyst and is not &quot;used up:&quot; by the process, so a weak mix works fine and is safer, too. Think of the lye, or washing soda - you could probably use table salt! - think of whatever you use as a virtual &quot;wire&quot; carrying the current from cathode (piece being cleaned) to the anode (that piece of rebar), carrying those pesky little rust flakes with it. A stronger solution works faster but the weak solution is a LOT safer. And that golf cart charger puts out 36-40 volts and enough amperage to charge 6 deep cycle golf cart batteries, so there is no need to use a stronger mix.</p><p>Come to think of it, I wouldn't try table salt. Sounds innocuous, but table salt is made of sodium and chlorine and those are not exactly &quot;user friendly&quot; in any form. Well, except table salt!</p><p>The source I got this from suggested lye and it works. I suspect that the same mix used with the washing soda would work.</p>
<p>Lye can be found either in supermarkets or hardware stores as drain opener or drain cleaner. Especially the cheap ones. Entrepreneurs feel they can make a ton of money buying Sodium Hydroxide cheap and repackaging it as drain opener and selling it higher as a miracle chemical.</p>
<p>Not so easy to find any more around here Buffalo, MN. As it is one of the chemicals used in meth production, so it has been removed from store shelves around me.</p>
<p>I have seen YouTube videos that people used Vinegar to remove rust. No electrolysis. very clean and as you said, rusts very quickly after the part is removed from the vinegar. Need to apply a thin coat of oil to protect it.</p>
<p>Wikipedia:</p><p>&quot;Lye&quot; is commonly an alternative name of <a href="https://en.wikipedia.org/wiki/Sodium_hydroxide" rel="nofollow">sodium hydroxide</a> (NaOH) or historically <a href="https://en.wikipedia.org/wiki/Potassium_hydroxide" rel="nofollow">potassium hydroxide</a> (KOH), though the term &quot;lye&quot; refers to any member of a broad range of metal hydroxides.&quot; Highly alkaline substance</p>
<p>Thank you, Chief. That was interesting to read and understand.</p>
<p> Were those diagonal cutters frozen tight? I have several tools like that that are rusted inside the joint. Naval jelly does not penetrate there. How does this do?</p>
<p>I would be interested to know that also. I have had some success by soaking frozen tools in BP Blaster for a few days. Or I soak them in The Works toilet bowl cleaner, it is liquid not a paste like Navel Jelly, it is a fairly strong acid so some safety precautions are necessary and a baking soda rinse once the tool is cleaned and oil of coarse. I also heat the tools to dry them rapidly then coat with oil as they start to rust rapidly after the acid bath.</p>
<p>If you are looking for a penetrating-type oil, brake fluid works better than almost anything at loosening stuck bolts. </p>
<p>I never thought to try brake fluid. Especially after what I seen what a spill can do to a car if not cleaned up promptly. There are all sorts of home concotions like 50/50 mix of acetone and automatic tranny fluid, another is to heat the part enough to melt candle wax into the joint.</p>
<p>Yes, they were totally rusted together and impossible to move. Worked freely once out of the electrolyte solution.</p>
<p>Two ways to free up</p><p>Blowtorch on one half of the box joint then penetrating fluid, white sprit or WD40 - keep gently working the joint and it will go.</p><p>The other way is to freeze one half - commercial product or plumbers pipe freezer spray, plus the lubricants as above</p>
<p>Wow, that's awesome !!! Thank You for sharing !!!</p>
<p>Love it that your cruising in your Vintage RV, Cheese Queen. I'm much the same way. Happy Travels </p>
<p>Same to you!</p>
<p>That's one heck of a garage sale find! If no one has told you, that's a 1937 S&amp;W 1917 contract model in .45 ACP/AR that was made for the Brazilian Navy. A boatload of them came back in the 1990's (in about that condition).</p><p>Great Instructable!<br></p>
<p>Yes, we know :) TY</p>
<p>There are many articles and Instructables about rust removal using electrolysis, this is a good one. My three points are, from practice:</p><p>1 - instead of steel anode (rebar) try a graphite electrode. It does not corrode as steel, you get much less &quot;broth&quot; on top of your electrolyte in the container, although since graphite available as a compound of the carbon with some binder, it will slowly wear too, but does not need cleaning. You can salvage some graphite rods for small projects even from a dead lantern battery, most older ones have the central electrode made of a carbon rod. Wear gloves when disassembling those. For larger projects try eBay.</p><p>2 - if you have a variable power supply - for this task the current stabilising ones are best - adjust the current to get just visible bubbling, if your setup is bubbling too hard you are actually electrolysing the water with the excess current, and not really speeding up the rust removal. As mentioned for safety, the more bubbles, the more hydrogen has been freed up from its bond with oxygen and the more important to allow this gas to escape safely into the (open) atmosphere.</p><p>3 - I found that the process is much faster if you do it in a plastic bowl that fits inside an ultrasonic cleaner, the ultrasound cavitation dislodges the freed-up particles from the surface, which fall to the bottom, the surface remains more conductive, which makes the process faster; and the end result is easier to clean up.</p><p>I use a hair dryer or a heat gun to dry the freshly washed and cleaned items, before oiling.</p><p>Good luck!</p>
<p>cool idea. thanks</p>
<p>I have had great success removing rust( iron oxide) with a simple solution of molasses in water. Nothing else needed. Just mix a tablespoon per pint of water in a plastic or glass tub. Immerse object and cover over to stop bugs getting in. After a few days somewhere nice and warm you will notice a thick scum on the top.your de- rusted treasure awaits you below this!. Non toxic,non polluting and actually quite tasty!. I dispose of old solution on compost heap and can report great vegetables!</p>
<p>Any idea how it works? Molasses as far as I know, are the residues of sugar refining, and as such, should be chemically inert. Don't molasses get used in rum production? I just can't think how this works unless it starts fermenting or something.</p>
<p>on a very pleasent tour of the rum distilery on st lucia we were shown the pipeline where the molasses where unloaded from tanker ships as there is not enough sugar cane produced on the island.</p>
<p>My grandfather worked as a mechanic at a bulk sugar plant on the island of Kauai in Hawaii. When we kids took a little too long in doing something, he'd complain that &quot;we were slower than molasses being pumped uphill in the winter&quot;. It was pretty funny, and I always wondered how he knew about winter and molasses, since it never gets that cold in Hawaii.</p>
<p>If I remember correctly, molasses is slightly acidic. Could that be the agent?</p>
<p>Not sure just how it works but as a side note molasses cones from sorghum cane not regular sugar cane.</p>
<p>We grew sugar cane in Hawaii until they took the technology overseas to make it cheaper. The only sugar crop in the US that won't result in molasses is beet sugar. From raw sugar to turbinado sugar to refined white sugar with molasses output, it can all process out of sugarcane.</p>
<p>the rum distillery on st lucia uses molasses from sugar cane imported now but previously grown on the island. It can be made from sugar beet, sorgum and possilbly others as well and is also known in britain as black treacle. its basically a residue of refined sugar production and is added to refined white sugar to produce brown sugar. I didn,t know about sorgum though learned something new great !</p>
<p>Anything that will conduct electricity would work. I suspect molasses is a mixture of several compounds, some of which are electrolytes, so it allows electric current to pass through it.</p>
<p>The molasses solution has nothing to do with electricity - it's not being discussed as an alternative mixture for electrolysis. It's simply a &quot;make molasses solution, soak rusty item for days/weeks, then remove and wash&quot;. </p>
<p>I've done this too, &amp; the stuff I read was that using regular molasses, not using unsulphured, would work better. Likely a chemical reaction from the compounds in the molasses, possibly the sulphur. I'd love to find out what was happening. </p>
<p>wow have to try that one thanks mate</p>
<p>I use vinegar for rusty tool, it works.</p>
Thanks. Very usefull. A question; Does it work for brass and copper??
<p>Thank you Cheese Queen and Thank You <a href="https://www.instructables.com/member/Chief741A" style="">Chief741A</a></p>
<p>Thank you for the Instructable. Very informative, very educational and useful.</p><p>Will try this experiment, this week.</p><p>Cheers.</p>
<p>I did this using a large storage tub with eight pieces of re-bar tied <br>together with 10GA copper wire - essentially surrounding the object to <br>be treated and used a battery in parallel with the charge and a solution<br> of Soda Ash Light [the trade name for sodium carbonate (Na2CO3)] and <br>water.</p>
<p>Vinegar also works to remove rust. I have used it to clean up rusty nuts and bolts for a restoration project I was working on.</p>

About This Instructable




Bio: Hubby and I have given up the ordinary in order to live and travel full-time in our vintage motor home. Our St. Bernard dog and ... More »
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