Introduction: Rusty Junk to Useful Stuff EASY With Chemistry!

Picture of Rusty Junk to Useful Stuff EASY With Chemistry!

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

Picture of 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

Picture of 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

Picture of 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;

Picture of 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 5:

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Step 6:


sharpstick (author)2017-06-20

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?

Gordyh (author)sharpstick2017-06-20

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.

Cheese Queen (author)Gordyh2017-06-22

If you are looking for a penetrating-type oil, brake fluid works better than almost anything at loosening stuck bolts.

Gordyh (author)Cheese Queen2017-06-22

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.

JimI8 (author)Gordyh2018-01-05

ATF and Acetone is a myth. They DONT mix. They are like oil and water and separate within seconds. Cant be done. I tried it and you just cant mix the two.

bil67com (author)Cheese Queen2017-12-26

It also works to recondition black plastic parts like fender flares, brake and clutch assemblies on motorcycles, anything that the sun has eaten up.

CharlesD82 (author)sharpstick2017-12-26

Yes, if you leave them in long enough (overnight, or a day or so), it will totally remove all of the rust and unfreeze them. I have had parts that were completely jammed to the point that I couldn't close or open them with extreme force. After letting them soak for a few days, they were like new.

The best part of this process is that it will only remove the rust, not the good metal. If you're worried about soaking something that's heat treated (because you could develop hydrogen ions in the metal), just place it in an oven @ 400 degrees for an hour after treating.

inchman (author)sharpstick2017-12-26

Here is a trick I try when 'pinchy things' (technical term) are frozen shut...

First, dip them in some diesel fuel for a little bit. If that doesn't work, stick them in some fine sand or other grit. With some muscle and luck, I've haven't lost yet!

Cheese Queen (author)sharpstick2017-06-22

Yes, they were totally rusted together and impossible to move. Worked freely once out of the electrolyte solution.

PhilS43 (author)sharpstick2017-06-20

Two ways to free up

Blowtorch on one half of the box joint then penetrating fluid, white sprit or WD40 - keep gently working the joint and it will go.

The other way is to freeze one half - commercial product or plumbers pipe freezer spray, plus the lubricants as above

Chief741A (author)2017-06-20

I have used this technique for years, but in a slightly different fashion...

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.

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.

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 "new" anode. You will be generating a significant cloud of red dust, I wear a simple face mask. My shed isn't exactly "tight" - more like a small pole barn - so I do this indoors, but it's best done outside.

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...

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!

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 "new" look. Speaking of looking "new"... this process does not remove or fill in rust pits in the metal. It only removes the actual rust.

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 "derust" everything in sight, you find that you get interested in other stuff!

JohnC430 (author)Chief741A2017-06-21

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.

inchman (author)JohnC4302017-12-26

I use vinegar for rust removal all the time. Best part is that it requires no electricity and in the end, you just have rusty vinegar (no other chemicals, I believe.) I've always wondered if electrolysis is better, faster, etc. One day, when I have two items fairly equally rusted, I'll have to try a comparison.

DanC66 (author)inchman2018-01-03

Vinegar plus DC does the trick! I've cleaned little bits and bobs with vinegar and a 9v battery. Kills the battery in no time but it's very rewarding in a Victor Frankenstein fizzing stinky process kind of way.

Norm1958 (author)JohnC4302017-12-26

Vinegar works good, it's acidic. The standard white vinegar is about 4% acetic acid, pickling vinegar 7% and I've found at our local Home Hardware store 10% Cleaning Vinegar. I had some 20% from a mayonnaise factory and it would strip the shale off hot rolled steel overnight.

AlanB150 (author)Chief741A2017-12-26

Good post. I researched the electrolyte situation a few years ago. There was a chemist from the US advocated Arm & Hammer, but with lye added. Not much, but it did make a difference. The power supply, if it is a battery charger, will not deliver very 'clean DC. It needs either a capacitor, or, better still a battery in parallel to smooth the output. You'll find the voltage and current available will be greater. A fuse, in case of shorts is desirable, but a pain to keep replacing when setting up the system. I use a couple of high wattage bulbs instead. When it shorts, the lghts take the current, that's all.

JohnC430 (author)Chief741A2017-06-21


"Lye" is commonly an alternative name of sodium hydroxide (NaOH) or historically potassium hydroxide (KOH), though the term "lye" refers to any member of a broad range of metal hydroxides." Highly alkaline substance

XTL (author)JohnC4302017-07-07

any salt will do - the alkalinity means it has spare ions (OH-) to aid current flow. Table salt is Chlorine based so will give off chlorine atoms which will become gas (not so good for you) or bond with the water to give HCL which is hydrochloric acid - which will eventually neutralise the base alkaline solution (all the acid Hs join the base OHs to make neutral H2Os).

So Baking soda is a good readily available alternative and not as strong or dangerous as Lye (NaOH). Its actually NaHCO3. WHich releases CO2 rather than Chlorine in the reaction. (Still acidic so eventually will neutralise the solution. You'll know - it will stop working. So what you tip out is basically neutral (pun intended)).
This is why baking soda and Vinegar Lava volcanoes is considered a safe experiment for children to do.

Metcalf32 (author)Chief741A2017-06-20

If substituting lye for the washing soda, what mix ratio would you use?

Chief741A (author)Metcalf322017-06-20

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 "used up:" 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 "wire" 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.

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 "user friendly" in any form. Well, except table salt!

The source I got this from suggested lye and it works. I suspect that the same mix used with the washing soda would work.

GaryV15 (author)Chief741A2017-06-21

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.

Gordyh (author)GaryV152017-06-22

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.

sreeci (author)Chief741A2017-06-20

Thank you, Chief. That was interesting to read and understand.

lgroger (author)2017-12-30

I find this really interesting but can I ask a stupid question? Water and electricity are generally a dangerous combination - what happens if you touch the water during this process?

DanC66 (author)lgroger2018-01-03

The charge is so low that it probably won't do you any harm, though you should be wearing rubber gloves if you're putting your hands into water with soda in it anyway. The bigger danger is getting your hands wet and then touching something connected to the mains supply.

Safety first!

Rebou (author)2017-12-30

There has been a lot of comments to this article, with a plethora of advice to the article, all have been constructive. It would seem that there is a LOT of knowledge out there, I'm going to try this on something, all I need are the bits and bobs that go toward the end result.

Happy New Year everyone, have a good new years eve and I hope you all ahve a great 2018.

ldubia (author)2017-12-26

Will this process remove paint from a part. I am considering micrometers that are rusted and frozen. I am wondering if this will work on them.

BigAndRed (author)ldubia2017-12-27

If you have micrometer that badly rusted then throw in the bin as it will be useless as a precision instrument after the rust treatment.

osterac (author)2017-06-20

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?

sreeci (author)osterac2017-06-20


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.

So, coming back to your curiosity, please assume, that the Author i.e.: Cheese Queen was using a 12 Volt battery Charger @ 10Amps.

Please thank the Author as most people have already done.

Thank you, OsterAC

clothier_bruce (author)sreeci2017-12-27

A car battery is referred to as '12V', but that figure isn't meant to be taken literally: it depends. When you charge it up the voltage needed is 14 to 15V. Modern chargers are sophisticated electronic devices and who knows what they get up to, but for electrolysis you'd want an old-fashioned el cheapo charger. The maximum current would depend on how expensive and heavy it was: a big one might do around 10A, but I think most bog-standard chargers opted for around 4A. But cheap chargers ( all you need for this ) were just a transformer and rectifier bridge. which gave dirty DC as there was no capacitor. For crude charging this was perfectly OK and also perfectly OK for electrolysis. The disadvantage for a battery was that the voltage output was about 18V open-circuit. This figure also has to be understood: the transformer was 'loose-coupled' so the current became self-limiting - a safety trick. Nevertheless, if the battery was left permanently attached, it boiled dry as these cheap chargers didn't go into trickle-mode. For that you need some electronics. Bottom line: an old cheap battery charger is a lousy battery charger - buy a nice electronic one. But it would be a terrific choice for basic electrolysis.

J DeweyJ (author)sreeci2017-06-20

Maybe you should say, or have said, a "car" battery charger. Battery chargers are NOT always 12 volts. I have plenty of batteries, even some SLA ones that are less than 12 volts.

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.

brainping (author)J DeweyJ2017-06-23

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:

An automotive battery charger, 10 amps or bigger.

JohnC430 (author)J DeweyJ2017-06-21

and you breathe the rusty dust... rust dust!!!

J DeweyJ (author)JohnC4302017-06-22

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.

rhemus (author)J DeweyJ2017-06-22

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.

Gordyh (author)J DeweyJ2017-06-22

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.

Cheese Queen (author)J DeweyJ2017-06-22

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.

ArifSae (author)barqzrd2017-06-25

I feel fellows are getting in useless debate over voltages,

more voltage = faster the process

Braindead63 (author)2017-12-26

I'm not an expert, but I think that the anode should be any steel except stainless.

My apologies if I am in error. I make mistakes when it is time for it.

cstgwr (author)2017-12-26

I am just recovering from hurricane Harvey in Houston. My tool chests were completely submerged in water for 10 days and have been in storage resting for the past three months.
I will definitely give this a work out!
Thank you for the post

salacerda (author)2017-12-26

What a strange thing, the coat of arms printed on this weapon is the coat of arms of the Republic of Brazil, it is owned by the national estate of the Brazilian state, how did it end there ?? lol

MarkI36 (author)salacerda2017-12-26

There are a lot of firearms made in Brazil that get imported to the US.

CharlesD82 (author)MarkI362017-12-26

It’s Smith & Wesson 1917 commercial model that was made in 1937 for the Brazilian Navy.

They got reimported back to the US in the 90’s

salacerda (author)MarkI362017-12-26

Thank you for the answer, I was curious with fact, more interested in the history of the weapon, if it belonged to a Brazilian diplomat or military who lived in your country who was perhaps your relative.

markonevet (author)2017-12-26

If, big if, you have an air compressor and glass bead blast cabinet, de-rusting is a whole lot faster and less messy. The above is a good way if you have neither the space or money to buy sshop tools

ThatMouse (author)2017-12-26

The article could be greatly improved by explaining how this is better than using acids or alkalines alone, and which is best for the different types of metal, and the differences in cleaning rust vs grease or paint.

www139 (author)2017-07-09

This is awesome! Might come in handy when I need to clean some tools. :)

TsungH (author)2017-07-03

This is a good method for steel items. That final soot you get is due to the deposition of iron from the anode. I.e. material is going from the anode to the item you are cleaning. Now if the item you are cleaning is made of something else, you might need a different anode for better results. Otherwise you may end up coating the item with a layer of iron. :) Good idea nonetheless!

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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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