Electrolysis - A Superior Cleaning Process

20 years of success in metal cleaning

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Updated August 2021. Based on experience, recent discoveries and feedback from internet friends.

Latest additions: Important notes on POWER SUPPLIES. Almost ALL automotive battery chargers available to the average consumer are Automatic Rate. These may not work without a 12 volt battery in parallel.
Please read additional detail in
section <Materials Required>

If any of the following is unclear or technically inaccurate, I beg to be corrected.

Many 100's of questions and favourable comments have been sent to me about this...from all over the world.. Not one dissatisfied report! A few corrections but mostly good news!

<What is Electrolysis?> - <Indirect Electroysis> - <What can be cleaned?> - <Materials Required> - < Safety>

<Setup & Procedure> - <Special Methods> - <ReUse /Recycle> - <Questions & Answers> -
<An interesting use for electrolysis- a soap maker> -

<User Feedback>

An electrolysis primer - Introduction

One of the most tedious jobs we encounter while restoring old iron is the process of removing many layers of paint and rust as well as freeing up seized bolts and pistons. The following introduces you to a method of parts cleaning that has proven to be the most effective means of de-rusting and paint removal I have ever used.

A word to the wise, slower is better. Trying to clean anything fast and without care and attention may result in badly pitted and damaged items. Using high current and a large positive electrode eats away at steel (and anything metallic) in a non-uniform and aggressive manner leaving pits that may be worse than what rust did to it. High voltage (moreso than current) can also cause hydrogen embrittlement (covered in more detail below).


The electrolysis process has been used by archivists for years to clean metal objects. I saw a show where a 1700's vintage French brass cannon was cleaned to reveal the complete Royal Insignia, and this was after 250 years in the sea. I had always expected it was too expensive and complex but it is not.

I can personally vouch for this process since it was used exclusively for the cleaning and un-seizing of my own engines and machinery. Anyone who has ever tried to clean up rusty iron (or any metal) will embrace this method with a passion equal to their love for the object itself.

A specific experience with this process has been recently tested when I overhauled a Type J, twin cylinder Atlantic Marine Engine. This engine was no exception to the state in which we often find our engines. The parts that were not covered in 10 layers of paint, were heavily encrusted with rust and many parts (including both pistons) were seized solid. The engine is now completely apart and clean using electrolysis exclusively and without the use of rotary wire brushes, chisels, flame heat or excessive force. And it is cheap and easy to implement and is even more environmentally friendly than the use of caustic and petroleum-based cleaners. There are no foul odors and the solution (if you use washing soda) is not irritating to the skin.

I finished restoring my grandfather's South Bend 9" Model C lathe (after it had been missing for 30 years). I used electrolysis exclusively to remove paint, rust and grease. For more info on South Bend Lathes visit the group at Yahoo. The members are helpful and enthusiastic. See more of my lathe restoration

What is Electrolysis?

For the purposes of the information contained herein, electrolysis is a process that passes an electric current through an Electrolyte, causing the migration of the positively charged ions to the negative electrode and the negatively charged ions to the positive electrode.

Simply put, if you connect a power supply to a container of liquid with 2 rods immersed in the liquid, chemical changes occur to both the rods, which must be a metal (or otherwise conductive), and the liquid, (electrolyte).

The process of electrolysis is not new, in fact it is as old as electricity itself. The same process occurs naturally when a metal in the environment is exposed to a reactive liquid such as salt. A small battery is created. Lead-acid batteries of today produce power by the process and electroplating is performed by using electrolysis. For our purposes, we are trying to remove paint, grease and rust from metal. Rust and corrosion is formed by electrolysis. We will use the same method to remove it, and more.

Electrolyte - A substance, in solution with water or another liquid, which is chemically changed by passage of electric current through it.

The electrolyte we use and refer to is the substance you mix with water in a bucket into which you place an electrode and the part you wish to clean.

Ion - An atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons.

The particles of metal which travel from the part being cleaned to the electrode are in the form of ions. An atom of iron (for example), once acted upon electrically through an electrolyte, is broken away from the base metal and becomes an ion with a negative charge. It travels through the electrically conductive electrolyte and goes to the electrode since it has an affinity (attraction) for the positive electrode. At that point the ion will lose its negative charge and either stick to the electrode or drop to the bottom of the bucket. If the particle is small and light enough, it may become part of the electrolyte solution.

What is Indirect Electrolysis? New 2012

Also referred to as "ion blasting", it is a alternative method that has recently been introduced to me. Indirect electrolysis involves placing an item to be cleaned between (not electrically connected to) 2 electrodes connected to a good DC voltage supply. It would seem this method may be ideal for ensuring that no hydrogen embrittlement occurs because the effective voltage on the item you are cleaning would be a fraction of the power supply .

Yet-unproven comments suggest that when cleaning metals, the item you are cleaning becomes both the negative and positive (anode and cathode) of a circuit. This may suggest that one side will get nicely cleaned and the opposite side will get pitted/eroded. For metals it may not be very useful.

If cleaning a non-metallic item, such as a porcelin sink that has been underwater and covered in crustaceans, (think of Titanic artifacts), the ion blasting would gently brush the item to remove softer deposits. Unbaked clay would not be a good choice and many items would be too soft for this.

Experments are needed and more will follow when known.

What can be cleaned?

The greatest success has been with steel and cast iron but essentially any metal can be cleaned or for that matter any electrically conductive material. But special caution is needed with aluminum or plated items. The process removes layers of metal at a molecular level and very slowly (if washing soda is used).

Some warnings which may apply to your project:.

"Light" metals such as aluminum, zinc, white metal or other alloys break down much quicker than steel, cast iron or brass. I think it's because at the molecular level, there is a weaker bond, but I am not a chemist. A smooth aluminum surface that has light surface corrosion can still be cleaned with electrolysis, but only immerse the material for short periods (15 minutes) and clean with a soft brush. Longer periods will discolour, badly pit or even completely dissolve aluminum etc.

Also, materials with a thin or not-well-bonded electroplated surface may be adversely affected by long periods. The plated surface may actually peel away. Experimentation is required no matter what you are working with. Try short immersions first and gradually lengthen the periods. My main tests on heavy, thick cast iron and brass parts show that they can be left "cooking" in the electrolysis bath for hours, days even weeks with no noticeable loss of metal and the brass may have some tarnish or discolouration. This is cleanable with conventional metal polish and/or a buffing wheel.

Items that have wood or leather or plastic. Some things you may want to clean also have leather wrapped handles, wooden bases, or plastic pieces attached.
Most plastics or Teflon will not be affected yet I have found that certain plastic become stiff or brittle and discoloured after electrolysis.
Wood and leather can be badly affected by this process. Leather can turn to mush, wood turns into pulp. In any of these cases, remove all non-metal parts from the unit first. If this is impossible, selectively bathe only the metal parts. Otherwise you should seriously consider using another method to clean the metal.

Precious metals,(gold or silver) can be cleaned but;

a) Some amount of precious metal is removed and this may be highly undesirable.(I did try a dirty gold neck chain. It worked but likely devalued it).

b) If the item is plated (brass, gold, silver), it may peel off the plated layer and effectively ruin it if it was a simply hot-dip process.

c) Coins and other items with fine detail can be cleaned but the delicate lines and raised words may be lost on badly corroded coins. If a truly vintage coin, other methods should be tried first.

So in general, experimentation is required while taking notice of the cautions outlined above. So don't blame me if your aluminum carburetor/engine block dissolves overnight. Or if your silver-plated water jug is reduced to the original tin shell.

I can't emphasize enough that aluminum requires special care. The polished housing on a motorcycle engine can be pitted and etched leaving a very poor mottled surface.

Other information on what you can clean and how to clean it is in Questions and Answers.

Materials Required - In addition to the part you are trying to clean, you need:

A non-electrically conductive container large enough to hold the parts you want to clean, (i.e. a plastic bucket or for large engine parts perhaps an old (fibreglass) bathtub ). There are other containers like a 45 gallon (about 200 litre) plastic drum that are used for soap and other materials sold in bulk. They are sometimes available cheap or free at recycling centres. An entire single cylinder engine could be put in one of these.

You could use a copper, stainless steel, steel or cast iron bucket, sink, pot etc. connected to the POSTIVE post as long as you are careful not to let the part being cleaned touch the side of the bucket (short circuit will occur).


Oct 2020 Notes on power supplies!
A problem that did not exist 20 years ago
was the unsuitability of automatic, car battery charger. ANY low voltage DC power supply would work. For simplicity and ease of access, the common 12 volt battery charger was the ideal low-cost solution, readily available at many stores. But many electronic items have a power adaptor that will output 6, 9, 12 volts DC (a computer laptop power brick [direct current] would do) -look for 2 amp or higher rating. These have been used successfully for smaller projects. I did not immediately suggest those since not everyone has boxes of used "stuff" in their workshop as I do. Automotive chargers used to be fixed rate 4, 8, 12 amp and higher.

NOW, Automatic Rate chargers are the norm and all chargers, from cheapest to Auto Shop grade are probably auto-rate.  The auto-rate charger will charge at a high rate initially (based on the capability of the charger) and decreases current flow as the the battery charges up. This stops the serious problem of overcharging a battery which can ruin it. The older,  fixed-rate chargers (don't think you can buy one anymore for the average consumer) would put out a fixed 4 or 6 amp (trickle charger) or 10 to 20 amp, fast charger.  In either case, leaving these connected to a car battery (lead-acid configuration) unattended, would potentially damage the battery. For electrolysis purposes, this is ideal since you want  4 amps or better constantly available to clean axe heads, cast iron pans, stove or engine parts etc.

HOWEVER, my automatic charger (Canadian Tire brand) will not output anything unless the load already has a hint of power left in it. As long as the battery has a few volts left, even 3 or 4 rather than fully charged 12 to 13 volts,  the charger will output power. IF the battery is so dead it has not a hint of power, the charger won't do anything. This surprised me when I got my first new style charger. You can't hook up a 12 volt light bulb to it, it won't turn on. Rather useless since I often used a charger to test 12 volt bulbs and appliances.

How does this relate to electrolysis? When you have set up the electroysis bath with, for example, a rusty steel wrench and a piece of scrap metal connected to the positive lead, there is little or no voltage produced or at least not enough to meet thr threshold the charger needs to "kick-in". If the cathode/anode were steel and aluminum or zinc, more voltage may be produced but aluminum or zinc should not be used as it deteriorates very quickly in the bath.

SO, aside from finding an old fixed-rate charger (which may have diminished rectification due to age and therefore poor for electrolysis use), or locating another type of DC power supply, the easiest solution is to get a 12 volt battery and connect in parallel (more on that follows). This can get expensive so you need to be more seriously using electrolysis to make it feasible.

A 12 volt battery or other DC power source with 2 amp or higher current capability. A battery (in conjunction [parallel] with a charger) will always give superior results. (What does PARALLEL Mean? See parallel circuit description below) A trickle (4 to 12 amps) battery charger can be used for small parts (see previous notes on the issues of newer chargers). A shop grade "booster" battery charger is quite effective for even large parts (i.e. an entire engine). 6 volt DC works as long as the current ability is high enough. Higher voltage DC sources will work of course BUT then it becomes a shock hazard. (see safety rules below) but moreover, higher voltage increases the risk of hydrogen embrittlement.
If you use a battery in combination with a charger, it is best NOT to connect the battery in SERIES with the charger since the highest current available is limited to the capacity of the charger; i.e. you can't push 100 amps of potential available battery current through a charger with a 10 amp capacity. (What does SERIES mean?)

Electrodes to connect to the positive battery terminal. Iron, steel, or any metal can be used. Aluminum used as the positive electrode deteriorates quickly. Iron (and maybe brass) would last longer but requires regular cleaning. The electrode can be wire, bolts, fasteners, screening, sheet metal or thick plate.

In addition, GRAPHITE rods
are a good choice and this is what would be used in a science lab setting. Science grade graphite rods are made of high-quality, ultra-fine graphite and highly compressed. They deteriorate slowly. But these rods may not be easy for average Joe to find. They won't be at you hardware store or hobby shop. A scientific equipment supply company might be the only source.

Carbon rods, such as what you find in a dry cell battery. They would be easy to obtain, if you want to dismantle a dry cell (with some caution of course, the chemicals inside are poisonous and can irritate skin). But common battery carbon rods are not as pure as lab quality graphite and may introduce an unacceptable resistance to your circuit. In addition, they may not be compressed as highly and I expect they may crumble. I have not tried it and no one has given feedback yet.

** Note ** Stainless steel can be used because this material seems to last longer and cleans easier. BUT, concerns have been raised which propose that as the electrode breaks down, the chromium in stainless steel becomes a compound (hexavalent chromium) which ends up in the liquid (or as a gas in the bubbles) and there is the potential for the mist from the bath to become airborne and inhaled. LONG TERM exposure to the skin has been related to skin disorders and LONG TERM inhalation of fumes has been linked to lung cancer.
, the US Occupational Safety & Health Administration has a considerable write-up on Hexavalent Chromium (CrVI) and say CrVI is produced from the high tempertures produced when welding, grinding or melting stainless steel or other metals containing chromium. This has been echoed by people I have spoken to about this, all experienced, qualified PhD Chemists and Materials Engineers. I now believe that the temperatures that occur with electrolysis as described herein are not nearly high enough to pose a risk. If you disagree, send documentation written by qualified experts that address the process of electrolysis in a water bath. Heresay and rumours just don't cut it. The concesus among my learned friends is that there may be NO hexchrome created in a water-based electrolysis bath, the temperatures are far too low.

Regardless of the electrode used, allow the liquid to evapourate and dispose of the remaining debris in a responsible manner.
NOTE: This was just suggested so I will pass it along. If you have used a stainless steel electrode and allow the electrolyte to evapourate, the dust and debris left in the container will have chromium dust in it. Pouring this out may cause the particles to become airbourne and inhaled. None of this dust would be healthy to inhale but chromium would be especially bad. So be very careful when disposing of the stuff or get rid of it while still in a liquid form to reduce the chances of any harm.

Water to mix with the electrolyte. Distilled water is not necessary but wouldn't hurt.

The electrolyte (see above for more information). I used Arm and Hammer WASHING SODA -a common laundry detergent. I have also recently had success with Arm and Hammer Ultra Laundry Detergent. Main advantages here are; easy on your skin, NOT as corrosive to the part being cleaned if you happen to leave the part in the solution, no worse than typical soap if it gets in your eyes, AND it leaves a nice soapy smell in the room (at least my "lemon-fresh" variety does). Also, the soap effectively gets rid of the putrid smell of old gasoline and oil. (great for cleaning out old gas tanks). Other soaps and detergents work fairly well and I'll leave that for you to experiment with.

Products equivalent to washing soda. Washing soda is mostly sodium carbonate (also known as soda ash), Na2CO3, and is a sodium salt of carbonic acid. It is also available as pH+, a pool and spa water treatment to raise the pH of water (make it more alkaline).

Other electrolytes I have tried . Take note of the cautions mentioned

Baking Soda - Sodium Bicarbonate. It works but has much the same properties as salt in that it is mildly corrosive once electricity is applied. I have used it only for brief tests. It is probably better to use it in place of washing soda than the others which follow.

Table salt- it is corrosive to metal in it own right. It also leaves a pungent chlorine smell behind. (It is sodium chloride). Very bad for aluminum.

Sea salt- it is corrosive to metal in it own right. But it is not the same as table salt. It actually contains many different types of dissolved minerals and salts. Some users have reported success with this. Very bad for aluminum.

Vinegar & acetic acid- Vinegar is a mild acid and has been reported to work but the smell it makes is undesirable. Lemon juice is a mild acid as well and smells better.

Trisodium Phosphate (TSP) - Found in cleaners for heavy-duty use such as household wall and exterior cleaners, driveway cleaner etc. It is more caustic than soap (harmful to the skin and eyes) so extra caution should be used. The warning on the container says "CAUTION: Contains Trisodium Phosphate. Wear rubber gloves and eye protection. Avoid eye contact or prolonged contact with skin. Wash thoroughly after handling. If eye contact occurs, flush with water for 15 minutes. Consult physician immediately."

Electrolytes suggested but not tried:

Molasses - apparently this had been used for many years and does not even need electricity applied. The cleanup after can be a bit messy.

These work but are NOT RECOMENDED:

LYE - Sodium Hydroxide - Corrosive to metal in it's own right. Causes much more gasification of the water (LOTS of hydrogen and oxygen gas). Very hard on your skin and even worse CAN CAUSE BLINDNESS if splashed in your eyes. Very bad for aluminum , white metals (zinc alloys) or thinly electroplated materials.

Battery acid (sulphuric) OR hydrochloric/muriatic, nitric, etc) - I don't need to spell out that one for you do I? Way too hazardous. Highly reactive to metals without adding current. Noxious / toxic fumes. Potential for severe skins burns and blindness if it gets in your eyes.


(PLEASE read it all, especially the cautions regarding safety. Review the previous information on the type of metals you can work with and the suggestions on the "electrolyte" to use.

THINK SAFETY!!! - There are numerous common sense safety rules.

Automotive-type and any(most) lead-acid batteries contains SULPHURIC ACID. Handle with care. Sparks around a battery of this type can ignite the hydrogen gases that are present inside the battery cells. This can cause the battery top to blow off and shower you with ACID. Make all connections to the battery first before plugging in the charger or connecting to the electrolysis bath. Potential for severe skins burns and blindness if it gets in your eyes.

Power and voltage - Although you may be working with a low voltage 12 volt system, some people may be more sensitive to that voltage. An unpleasant tingle will be felt if you touch both connectors from the battery or charger with your bare hands. More important is the high current capability. If you were to short circuit, the leads from the battery or charger, sparks will be created that could be a fire hazard. If you were to short circuit the leads with a coat hanger wire, a ring or necklace, it will glow bright red and cause burns and/or fire. To reduce the chance of personal injury, make all connections to the electrolysis bath before turning on the power. A shock hazard is more likely if you were to use a power supply greater than 12 volts.

Electrolyte - You may be using washing soda or other soap. They will not likely hurt your skin but splashing the soapy solution (which contains metal bits, grease and rust) in your eyes can't be good. If you use other electrolytes mentioned, they may be harmful to the skin and damaging to the eyes. Exercise caution

Gases produced - The electrolysis process splits water into it's elements, namely hydrogen and oxygen. Sparks (from the battery and connections) can ignite the hydrogen/oxygen mix. It is not enough to produce a Hindenburg-like explosion in your workshop, but it is flammable all the same so this should be done in a reasonably ventilated area and caution is advised.

Heat produced - Once the item to be cleaned has been in the bath for awhile, the water will get quite warm from the current transfer and may even be too hot to touch. This is a good way to help take apart seized parts without the use of torches.

Setup & Procedure

The example here uses a 5 gallon (20 litre) bucket. (The white bucket illustrated below is less than half that size) Use about 1/3 cup of washing soda in a 5 gallon bucket of water and mix thoroughly. If you are using larger containers, you will only need to add enough washing soda (or alternative electrolyte) to allow current to flow through the water. If you use other electrolytes, continue to add the substance until current flows (bubbling occurs). Excessive electrolyte simply uses more current without substantially improving the speed of the de-corroding process. Slower is better. After all, your old "whatzit" has been in the woods or under the ocean for decades or centuries,... what's a few more days?

Place the iron or stainless steel or other electrode (rods, plates, wire etc) in the bucket and connect the POSITIVE battery cable. There must be a good electrical connection. Clean off any rust or dirt that may impede current flow. It might be best to clamp the electrode to the side of the bucket to keep it in place.

To clean small parts, a small plastic tub and a battery charger may be all that's needed. A few tablespoons of washing soda was sufficient.

Connect the NEGATIVE battery cable to the part to be cleaned and place in the bucket. . There must be a good electrical connection. Clean off any rust or dirt that may impede current flow. The part could be placed on the bottom or clamped to the side of the bucket or alternatively suspended from the ceiling or from a piece of wood across the bucket. (The purpose for suspending the item is too allow more even cleaning all over at the same time.) Turn on the power. You will immediately see bubbles and froth coming from the electrode and the part.

Amount of bubbling depends on various factors described herein. Bubbles may eventually become a thick froth on top. NOTE: The froth is a Hydrogen-Oxygen gas mix and will burn if ignited.

You may have to leave the part in for anywhere from minutes to several hours to several days or longer depending on the extent of the rust and paint BUT USE GREAT CARE with aluminum or other light alloys. In any case, it is useful to occasionally check on the part and partially clean it as the rust and paint soften. This can be effectively done with a small hand-held wire brush or stiff bristle brush and steel wool.

Left: Paint begins to peel and bubble in minutes...Right: A light scrub with a toothbrush removes paint

Large flakes of rust can be easily scraped off, smaller pieces will brush off in time and molecular-sized fragments float off into the water and become part of the froth on top. Paint may actually soften and can be peeled off in sheets, several layers at a time. This process is also good at softening rust inside water jackets and other tight places that are often difficult to get to. In addition, electrolysis will, in time, soften the rust layer between the piston and cylinder wall making it easier to remove. The same process softens the rust between a seized bolt and its threaded hole or nut making it easier to remove without heat.

You can place several items in the bath at the same time but the more items (thus greater electrical surface area) there are, the more current flow is required. This also means that the stainless plate (if quite large) also increases the current flow. In addition, the proximity of the stainless plate (positive post ) and item to be cleaned (negative post) changes the current required. The closer they are, the more current required. (just make sure they are a little distance apart-otherwise a short circuit) When cleaning large parts, a fully charged, heavy-duty 12 volt battery will be dead in several hours. So either use a smaller electrode, increase the distance between the electrode and part or use a BIG battery and /or heavy-duty battery charger.

As mentioned above, the rate of electrolysis can be affected in numerous ways. To reduce the process, increase the distance between the electrode and the part being cleaned, reduce the concentration of the electrolyte or reduce the size of the electrode. In all case, this increases the resistance which decreases current flow and slows the electrolysis process.

You can use any DC power supply of any voltage.HOWEVER (1) Avoid high voltage just because of the shock hazard.(2) The higher the voltage, the greater the chances of hydrogen embrittlement. A battery charger will work, especially if used in conjunction with a battery. (The charger will help keep the battery "up" or if you use a shop type "booster" charger, it can be used by itself. A 4 amp trickle charger won't do much except for small parts). A problem I have found with some battery chargers (if you do not have a battery included in the circuit), is that the rectifiers that filter the AC to DC are poor. This means that some of the material that has been pulled off the item you are cleaning, gets reattached to the part because a small fraction of the current flow is reversed. While not a huge problem, the part will not be as clean as it could be. If connected to a battery, the "unclean" output from the battery charger is filtered but not rectified. (See more about this in the parallel/series circuit description below)

When you are finished cleaning the part, wash it with fresh water and dry it thoroughly over a heater or in the sun. The freshly cleaned metal will rust very quickly. It might be best to either prime the metal or spray with a light oil or penetrating oil (like WD40) to stop flash rust from occurring. Another trick is to rinse the item with COLD water and dry it as quickly as possible. Since the item is cold, the water does not evaporate so fast. If rinsed in hot water, the water film disappears before you can dry it with a cloth or compressed air and flash rust is almost certain to occur.

Also remember that ( with iron at least) if the part you have cleaned comes out looking badly pitted and rounded off, electrolysis did not necessarily do it. This is what the item looked like after natural corrosion ate into it. Yet pitting can be caused if caution is not taken.

Special Cleaning Methods

How to clean a bunch of small parts.

If you have a lot of small parts (like a bucket of bolts), you can use a stainless steel screen (a common kitchen strainer works) shaped into a pouch or mini-bucket. Place some of the parts in the screen and immerse in the electrolyte as if it were a single part. Connect the battery NEGATIVE to the screen. All the metal parts which touch the screen (and in turn, each other as the corrosion dissolves and the parts can electrically touch each other) are cleaned together. Use a brush to stir the parts around occasionally. This helps to remove loosened corrosion and improves the electrical contact between pieces. In time, all parts will be mostly de-corroded. Compare this to wire brushing 100 bolts individually.

Cleaning inside a tight area like a engine water jacket

Take a small diameter plastic or rubber hose, cut numerous small holes in it and slip a length of stainless steel wire through the length of the tube. Feed this assembly into the water jacket (or whatever you're working with) and connect the POSITIVE battery wire. The electrode is now inside a tight area and in close proximity to the part/area you want to clean without touching it. Getting all the loosened crud out can be a challenge but vacuuming, compressed air or turning the unit upside down to dump it out works. One problem is that the process causes large chunks of rust to drop off inside the unit. You may need to reach inside with a screwdriver or rod to break up the rust to get it out.

For cleaning inside of cylinders or other parts, use a stainless bolt or wire supported and hanging freely within the part. This will clean inside areas that can't be normally reached.

Gas Tanks

I have used this to clean out enclosed containers such as a gas tank . I have also received many positive reports from others that have had success cleaning car, truck and motorcycle gas tanks. Seal off the tank, (fuel supply ports on the bottom) and fill the tank with an electrolyte solution. Drop a rod or bolt into the filler neck or opening for the tank level sending unit. Suspend the bolt so it cannot touch the tank in any way and turn on the power. The process will dislodge gas varnish, rust and any coating inside and also get rid of the "old gas" smell. The solution may foam up and cascade over the tank so if cleaning a motorcycle tank with a good exterior paint job, Exercise caution, While the electrolyte in itself will not affect paint on the outside of the tank,  if the electrolyte foams enough to cascade over the tank while power is connected,  electrolysis can occur by passing current from the electrode through the foam and to the tank. This can potentially begin to lift the paint. Try to keep excess foam off the outside of the tank.

Cleaning large items

The use of a drum (45 gallon) was mentioned above. These are usually big enough to place an entire small engine in (or lathe bed or wood stove etc). Surround the inside of the drum with screen or sheet steel (stainless is better) and connect to the POSITIVE battery lead. Lower the entire engine or part into the centre of the drum using an engine hoist, chain block or suspended from the ceiling. Connect the NEGATIVE lead. Over time and with some brushing, the whole unit will be free of rust, grease and paint before you even take it apart. This will require considerable current so a large battery charger capable of maintaining 30 amps or more will be needed.

REUSE the electrolyte

After a while, the electrolyte gets quite dirty with suspended metal and dirt or grease. I have found (at least while using washing soda) that if you remove the electrodes, wires and parts from the electrolysis bath and leave the liquid to sit a few days, most material drops to the bottom. Siphon off the clear liquid at the top and re-use it, perhaps add a bit more electrolyte and water before starting the process again. HOWEVER, some material will remain in suspension and may affect (discolour) the part you are cleaning.

Example: If you have just cleaned a lot of brass, the electrolyte gets a green hue. Cleaning steel in this liquid may leave it with a slight brown discolouration. If this is undesirable, you will need a fresh batch of electrolyte.

If you don't intend to reuse the electrolyte and it was not used for extensive de-greasing, it can still be used as a soap to remove dirt and debris from metal. It is probably best not to simply dump the liquid outside in the ground as it may contain lots of metal and grease.
BUT more importantly if stainless steel was used as the positive electrode, the breakdown of the material will leave chromium suspended in the liquid and it would be considered an environmental hazard. It is best to allow the electrolyte to evaporate in any case and dispose of the debris left behind in an environmentally responsible manner. If stainless steel was used, it should be considered a hazardous waste.

THIS IS NOT A MIRACLE WORKER. Some good old-fashioned elbow grease will still be needed but the effort is much-reduced.

An Interesting Use for Electrolysis - A Soap maker

Around May of 2008, I was contacted by a woman in Tokyo, Japan in relation to the electrolysis process which she felt might be the technology behind a curious device that was marketed there (No longer made). It is a commercially made device about the size of a kitchen waste basket with 2 chambers clearly separated by a divider with holes in it. Each chamber has a drain spigot in the bottom. To use it, you mix a Sodium Bicarbonate (baking soda) solution and fill both chambers.
She claims that after running it for a few hours, the liquid on one side becomes a very effective cleaner, very good at removing/dissolving kitchen grease etc.
The theory at this point is that the 2 chambers are separated by a reverse osmosis (RO) type membrane which is fine enough to stop even bacteria from passing through (hence an RO system is commonly used to clean poor water for human consumption). Yet electrons are small enough to pass through such a membrane. But what is going on here?
After discussions with my "smarter-than-me" BioChemist brother, he confirmed my guess that if DC current is applied to a baking soda solution, yet the solution is effectively separated by an RO membrane, the solution becomes alkaline on one side, and acidic on the other. The alkaline solution is sodium hydroxide (NaOH) and the acidic solution is carbonic acid (H2CO3).
If anyone has additional information or guesses on just what is going on here, I am forever curious about such things.

Of course my main question is why have a machine to make Sodium Hydroxide when we (at least in North America) can easily buy large bags of pure Sodium Hydroxide for not a lot of money? You could make 100's of litres of a cleaning solution with that.

Questions and Answers

What is hydrogen embrittlement ?- As best as I understand it at the moment, hydrogen (the smallest atom) from the electrolysis solution can be forced between the surficial molecules of the item you are cleaning. This in effect can destabilize the surface and introduce cracks that may not be visible without considerable magnification. It is more likely to happen during long periods in the electrolysis bath or high current and rapid cleaning. In many cases this will not be a concern but consider the following examples before you choose your electrolysis cleaning method:
- A thin band saw blade, already a hardened steel, can become more brittle or develop cracks that may cause the blade to break under use
- An engine connecting rod, normally under much stress while in the engine and running, can develop cracks and increase the chance of the rod breaking when the engine is run.
- Thin sheet metal, such as an antique car body that is already thin due to rust, can become brittle which will increase the chance of stress cracks occurring once the car is assembled and driven down the road.
These are all cases reported me and are more likley to have occurred because the user tried to clean the item too fast. As said many times, experiment first before cleaning thin or hardened items or any component that is likely to be under considerable stress.

What does it mean to connect a battery charger in parallel (or series) with the battery? When charging up a car battery, or boosting one car from another, you ALWAYS connect the postive to positive and negative to negative. This is an example of a parallel circuit. If, when working on a car and you connect the leads incorrectly, the sparks will really fly and the battery could even explode. The first image below shows the correct connection of the charger to the battery. In this case, the battery will initially provide the majority of the current with the charger "helping out". The voltage potential across the negative and positive posts will be about 12 volts. The charger supplies some of the current being used and keeps the battery from going dead as fast. When the battery does drain most of it's charge, the charger will still continue to supply power. In this case, the unclean DC that comes out of some battery chargers is FILTERED (A/C pulses smoothed out), but no additional rectification occurs.

This is typically how you want to connect the charger. It is the same as if you were trying to charge up the battery in your car. Connecting the charger leads in reverse may cause large sparks, and may destroy the charger. Also there is a possiblity of a battery explosion. A lot of sparks around a battery can ignite the hydogen gases that are ever-present inside the battery which can cause the top of the battery to blow off and shower you with sulphuric acid!!! (It happened to me!)

SERIES Circuit. You could potentially connect a battery charger in series with the battery but I have never done so and can't image why you would want to. It defeats one of the main purposes of using a battery, having high current available, yet it will help to rectify [create a clean Direct Current] the power coming from the battery charger or other A/C to D/C power supply). Although a battery in a series circuit will also help to rectify the A/C power supply (much as a diode or rectifier will), the current supply will be limited to the ability of the charger.So a 10 amp charger in series cannot deliver much more than 10 amps before the internal wiring becomes overloaded and melts.

In this setup, the postive charger clamp is connected to the negative battery post. The voltage potential between the postive battery post and the negative charger lead will be 24 volts, and the output will be a clean D/C. However, if you are using a charger with a rating of 12 amps, you will not be able to get more than 12 amps from this circuit as it is limited to the capabilty of the charger. There is nothing dangerous here, there just doesn't seem to be point to it for the sake of getting 24 volt output....it is unnecessary.

The instructions mention a preference for stainless steel electrodes. Why?

The electrode connected to the postitive battery contact gains material during the process of removing it from the part you are cleaning. Aluminum and steel hold on to a lot of this material, (rust, corrosion, iron or copper bits) and eventually create an electrical barrier which nearly stops the current flow through the electrolyte. Regular cleaning of this material is needed by scraper or wire brush. Stainless steel does not allow as much material to stick, so it requires less cleaning and attention. In addition, stainless material does not break down fast so will outlast steel many times over. (In spite of the concerns with the use of stainless material, I stand by the comments of the last 2 sentences if a GOOD QUALITY stainless is used). Admittedly, it is hard to know the quality of the stainless material you obtain. I repeat here; concerns have been raised to me that using stainless steel produces hexavalent chromium, a hazardous gas. I have yet to have ANY scientific evidence provided to me that proves that when using stainless steel in a water-based electrolysis bath, that ANY hexavalent chromium is produced.

Where to I get stainless steel?

Stainless steel is available in many forms. Wire, screen, bolts and thin or thick plating. These are mostly available at hardware stores or a bolt and fastener specialty shop. Stainless screen or plate may be available through a metal working shop that builds ducting or sheet metal products. New stainless is expensive but will last years. Try a scrap metal yard for pieces of stainless. You may even find pieces of automotive trim in an auto junk yard made of stainless.It was often used as door moldings and window trim.

I have observed electroplaters using a method called brushed plating to repair worn periscope shafts and am wondering if this process could be used for cleaning? 

Electronically, electrolysis is simply electroplating in reverse (reverse the polarity of the DC source). A significant difference is the electrolyte used. While washing soda etc is suggested here to allow current flow for electrolysis, the electrolyte for electroplating is a specific chemical solution for each metal plating process to allow the plating material to adhere to the base metal. However, the DC current supply should be just as useful for either purpose.

Can I remove the chrome plating from an antique weapon (a pistol)?

Probably not. The electroplating process, if done properly, will include an acid dip to remove all dirt, rust and oxidation. The item might be plated many times over. If the chrome (or brass or silver plating) is well-adhered to the base metal, electrolysis will not lift the plating.

Will electrolysis remove zinc/galvanized plating?

As stated previously, many types of coatings such as hot-dipped zinc plating or silver plating, if not well-adhered to the base metal (whatever it might be), can be undermined with electrolysis. It will lift, loosen and peel off. I found this out the hard way when I was trying to clean/detarnish a silver-plated water pitcher. The plating began to flake off. In that case it was no great loss but it was an unpleasant surprise all the same.

Can this be used to clean an all-aluminum motorcycle or other small engine?

If caution is used, it will help to remove layers of corrosion from aluminum. But if you are trying to free up a steel part within an aluminum casting, be warned, the aluminum will be eaten away much faster than steel. A shiny motorcycle engine case will be pitted and discoloured quickly. This could effectively ruin the machine. If you have no other choice, it may be worth a try.

Will brass and/or babbit be eroded using this process?

Any solid brass or copper will not be adversely affected outside of some discolouration. The babbit (lead alloy) bearings found in many old machines will deteriorate somewhat faster than steel but the surface will not be quickly etched. The biggest issue is how well the babbit was adhered to the base metal (iron or brass). If the bond is poor, the babbit shell will be undermined and eventually come loose. If that is the case, you should be thinking of repouring the babbit anyway.

Does the part need to be degreased before the electrolysis process? Will electrolysis remove good paint on clean, non-rusted metal?

The part you are cleaning needs no special preparation outside of insuring a good electrical connection. Grease falls off the part and dissolves in the soapy solution in conjunction with the heat produced by electrolysis. Paint, even baked enamel, will eventually peel off the base metal in single sheets and will happen even on rust-free metal and good paint.

How can I adjust the rate of the cleaning process?

Opposed to buying a very expensive scientific grade power supply to adjust the current flow, it is simpler to either a) use less washing soda to make a weaker electrolyte, b) move the part being cleaned away from the electrode or c) add a load in series with the circuit such as a 12 volt light bulb or electric motor. In all cases, the resistance increases, the current flow drops and the process is reduced in effectiveness.

Can a small battery trickle charger be used?

Small battery chargers in the range of 4 to 10 amps may not be suitable. This is not because the current is insufficient but the quality of the direct current (D.C) is not good. Ideally, you want a pure DC source as that from a battery. Battery and trickle chargers must convert the 120/220 volt 50/60 Hz alternating current (A.C.) from your wall socket to 12 volts D.C.. The diodes (or rectifiers) which filter A.C. to D.C. are not very good in small and cheap chargers. The end result is the A.C. which gets through can cause as much material from the electrode to stick to the part being cleaned as what has been removed from it. If connected to a battery, the "unclean" output from the battery charger is rectified. This holds true for even a nearly dead battery. While the battery charger may be supplying most of the current after the battery is discharged, the battery still helps to rectify the current flow. Experimentation is essential in any case.

Have you cleaned springs using this method? I am wondering if there would be any loss of tension by running the current thorough it.

(Carefully review the section on hydrogen embrittlement above.) Yes I have cleaned springs and they should not be affected by electrolysis BUT low voltage should be used. A spring would normally only lose its tension through excessive heat or stress and electrolysis does not get that hot. HOWEVER, voltages above 1 volt start to introduce hydrogen embrittlement which can cause the spring to crack under stress. I expect that if the spring is quite rusty, it will already be weakened in the pitted areas where corrosion is present .

If I want to clean up something made of brass or bronze , what do I use as a sacrificial piece connected to the positive terminal?

I have not found that the type of positive (sacrificial) electrode makes any significant difference in the cleaning process. I have tried many different metals when cleaning iron or brass and there is no obvious difference relative to the effectiveness of cleaning an item.

I have hooked everything up but nothing is happening.

This has been reported many times and the reasons are always the same. The power supply is inadequate, the electrolyte is too weak, the electrode is too far from the item you are cleaning or the connections are poor. If all these are correct, something will happen, at least a bit of bubbling and foam.

User Feedback

The uses for this are quite broad with reports of successful use on stoves, lathes, engines and other car parts, tractors, WWI ordinance found on the seafloor and even Napoleonic -era artifacts. Here just afew of the emails:

....I stripped some old ornate heat grates, that are so ornate that the matching one's I've done in
the pst took almost an hour to sandblast. I also did an ornate iron fence finial, which I'm in the process of bondo-coating for the foundry right now. 1 of 16 has survived it's 140 history out front of our house, so it's time to replicate a batch.
This is definitely my new favourite way to clean stuff up. Stick in the bath and walk away. Thanks for all the help....Brad

.....I really appreciate the great tips you've given on cleaning metals electrically, and so have hundreds of of others. Seriously, I had searched for a way to remove commercial enamel labelling from little metal tins without damaging the tin-plating with abrasives, asphyxiating myself/my family with aggressive solvents, etc., when I chanced upon your page.  I linked it on my blog, and it is about the most viewd entry (blame it on the crafters, makers and steampunks).  The link is at http://offlogic.wordpress.com/2007/09/03/electrolytic-removal-of-enamel-from-tins/ . I just thought I should thank you directly.  You saved a lot of us a lot of elbow grease!.....Sam

....These Civil War artifacts have been in the ground for 150+ years and the electrolysis process is doing quite a job on removing rust (old iron, etc) so encrusted that sometimes I cant even find where to start (for a good connection).......  Thanks again for all your help and time, you truly are a "handy-man!"

...Thank you for your fine article. I am reading it in preparation for cleaning several pieces of cast-iron cookware....Lawrence

.....This is just a note to let you know that I have successfully de-rusted dozens of VERY rusty motorcycle gas tanks over the last 6 years or so....many thanks for your extremely informative and detailed writeup.... Rick

.....I am using the electrolysis cleaning method outlined on your website to clean a 13" South Bend lathe. I am completely impressed by the results I am getting. I typically leave the parts in the tank for 24 hours. The grease disappears, the paint comes off in sheets, and the rust is completely gone. Nothing left but bare metal! Thanks so much for creating the website you did. I have found the instructions very clear. Just didn't expect the method to work so well! Thanks again for your work! Ron C. USA ...

......I collect old cast iron frying pans and electrolysis gets them clean easily and leaves a nice finish. Beats the heck out of my old method of scraping, and the lye treatment that was suggested by someone. Bob S, USA ....

......I tried it last night using a trickle charger (8amps I think), seawater, steel bolt as anode (+) and connecting the negative terminal to the aluminum part. It is scary how well that works. I just did some less critical parts like handles and levers. About 15 min. loosened all the paint enough to make it a 30 sec. wire brush job. A careful inspection with the magnifying glass did show some slight pitting. I would hesitate to do this with aluminum parts that have precise tolerance surfaces like blocks or cylinder heads. Still I am extremely impressed. Even if I can't use this one on every part it will still save me tons of time... Henry, USA

Your feedback is desired. Tell me of your success stories or alternatively, problems you encounter. Have your questions not been answered?? I want to know.

For clarification or more detail of this process contact me, Philip, at: oldiron@antique-engine.ns.ca






Last modified August 2021