Posts Tagged ‘ electrolysis ’

Rust Removal Using Electrolysis

Why would you do this?

If you are a person who only buys new stuff at the big orange store you probably won’t need to remove rust. Myself, I am retired and have more time than money.  In other words, “Cheapskate”. I watch for garage and estate sales with old tools I can use. My garage is full of restored tools, most tuned to be as good or better than when they were new. “They don’t make them like they used to” is certainly true for woodworking hand tools.

This is my current favorite hand plane. Found at a flea market, all exposed surfaces had a good coat of rust and to further insult, someone had varnished over the rust. It now works beautifully.

Stanley 5 1/4 Derusted and tuned

Stanley 5 1/4 Derusted and Tuned

Rust removal is not limited to tools. There is an active Facebook group for people using electrolysis in large tanks to clean flea market cast iron cookware. Old car parts need it. I even saw someone had de-rusted a whole car. Near my home there used to be a restaurant “Key Wester”, in the lobby there was a Spanish cannon retrieved from the waters off Florida that had been cleaned with electrolysis. The sign said it was in the tank for months.

There are degrees of rust. I avoid tools with areas that look like scabs. Those will clean (with difficulty) but leave a pit in the surface that may or may not affect the function of the tool. An even layer of surface rust, even if heavy, will usually clean off to a usable surface.

Electrolysis won’t damage underlying iron but doesn’t actually remove the rust. It just changes the red oxide to a black form that is easily scrubbed off, so there’s still elbow work involved. Electrolysis in itself won’t remove paint or plating. But if the paint is loose, it may come off in the scrubbing. I have not had a problem with the Japanning used on hand planes coming off, though any coating that is rusted underneath may separate regardless of the cleaning method used.

Components

These are the things you need to get started.

A waterproof container large enough to submerge the subject. Best to use plastic. A metal container will possibly trigger a short circuit though I have seen people using steel tubs with good results. I usually use either a six gallon bucket or a three gallon bucket. Some of the cast iron cookware people use barrels.

Small Tank in Action

Small Tank in Action

 

Objects that won’t fit in a bucket can be handled by making a tank to suit. I have de-rusted several full size hand saw blades in a homemade tray consisting of a plywood bottom and scrap molding for the sides. I lined the tray with plastic sheeting and laid electrodes flat in the bottom.

Saw Cleaning Tray From Scraps

Saw Cleaning Tray From Scraps

A flat tray like this will only do one side of the iron. You have to turn it over every half hour or so. Also I found the plastic grid insulators left a pattern on the saw blade. To reduce that, just move the blade a bit every 15 minutes.

Hand Saw Blade Under Electrolysis

Hand Saw Blade Under Electrolysis

De-rusting and scrubbing can be a dirty mess so it’s best to do it outside the house. I usually move to the driveway and do scrubbing on an old plastic sign. It’s a good use for those placards left up after election day.

 

An anode (or anodes) at the inside edge of the tank. Anodes are connected to the positive terminal of the power supply. Steel plates are good, I have seen cut up coffee cans, discarded hacksaw blades, even rebar.  Remove paint or other coating facing the inside of the tank or they won’t work. Some people warn against using stainless steel because of possible heavy metal contamination of the electrolyte. However the cookware people on Facebook recommend ONLY using stainless, and I use stainless plate salvaged from electronic equipment, bent to clip over the sides of the buckets.

Avoid aluminum and galvanized steel. Aluminum will disappear and Zinc contaminates the electrolyte.

It’s a good idea to add a layer of porous electrical insulation. Too often one of the objects falls into the tank and can short circuit the power supply.  I use plastic grid cut from a milk crate over my larger anodes. Occasionally the plates need to be cleaned, so make any insulation removable. Multiple anode electrodes must be electrically bonded together.

Small Electrodes, Large Electrodes

Small Electrodes, Large Electrodes

 

A source of Direct Current. This can be from 3 to 24 volts, an automotive battery charger is typically used. A small one with 6-15 amp capacity is fine, lots of these show up at garage sales. Try to get one with a meter so you can see if you are drawing too much or too little current, and bonus points if the charger has a six volt setting. Switching down from 12 to 6 volts is an easy way to bring the current into range if you mix the electrolyte too strong.

Battery Chargers

Battery Chargers

Some newer chargers have short circuit protection built in and will not start if they don’t see at least some voltage on the leads. The charger above on the right has an “Activate” position that will source current no matter what into a dead battery. Also watch out for really old chargers that have Selenium rectifiers. They work but are inefficient and if you short one long enough to blow out the rectifier you can’t believe how bad it smells. DAMHIKT.

There are people using cast off PC power supplies for electrolysis but that’s way beyond the scope of this article.

 

Electrolyte to make the solution electrically conductive. The classic electrolyte is Arm and Hammer Washing Soda (Sodium Carbonate) dissolved in plain water. Many supermarkets carry it. Baking soda (Sodium Bicarbonate) works but is more expensive. People also use Borax but I have not tried it. All these are non-toxic, you can pour it down the drain or on the lawn when you’re finished.

Sodium Carbonate

Sodium Carbonate

The starting recipe is one tablespoon per gallon of water. That’s about a handful in five gallons. Washing Soda doesn’t dissolve easily in cold water, if you heat the first gallon it will dissolve better. I fill the tank half way then pour in water heated in an old coffee pot. Stir until the Carbonate dissolves then fill the tank the rest of the way.  Undissolved powder left in the bottom of the tank will eventually go into solution because the mixture warms from the heating effect of the current which gradually increases the power draw, possibly overloading the charger long after you’ve started it up.

 

Scrubbing tools. Again, electrolysis doesn’t remove the rust, it changes it to a form that is easily scrubbed off.  Most chemical de-rusting methods are the same in this regard. My favorite scrubbing tool is a brass bristled brush. Stiff enough to remove black oxide but not so stiff that it scratches cast iron. Brass won’t round over edges that shouldn’t be rounded over, like the mouth of a plane. Rotary steel wire brushes will do that. Brass brushes used to be common in the barbecue section of  hardware stores, but I only see steel these days. Another source is suede brushes from a shoe repair shop.

Stiff plastic brushes may also work, and Scotch Brite scrubbing pads are used often.

Scrubbing Station

Scrubbing Station

Keep a bucket of clean water next to the scrubbing area. When a piece of iron is scrubbed clean it will flash rust again very quickly in the air. The easiest way to avoid re-rusting is to store the cleaned parts submerged in fresh water. That may be counter intuitive but it keeps oxygen away from the metal until you are ready to dry the piece.

Scrubbing with a brass brush when the part is still wet with carbonate solution will transfer a small amount of brass to the surface of the iron giving the part a goldish cast. I like it, I think it looks antiquey. If you don’t want color, just rinse the part good in clean water before scrubbing. I scrubbed the saw plate in the above picture with a copper brillo pad and, surprise, the saw has a copper tint now.

 

Set up the electrolysis tank. So far we have a bucket full of Carbonate solution with anode electrodes around the inside surface. The iron components to be de-rusted must be carefully hung in the middle of that solution so they don’t touch the anodes. I use a board with fat copper wire threaded through numerous holes, this forms the cathode and is connected to the negative terminal of the charger. The board has screws near the ends spaced so it can be wedged onto the sides of the bucket, providing some security against parts accidentally moving and causing a short circuit. Battery clips soldered to the Copper buss support smaller items while larger parts like a plane body get dangled from their own wire wrapped around the cathode buss. A large part may be drawing several amps so you need at least #18 wire. Remember, positive to the outside anodes, negative to the tool.

Cathode Hangers, Large Tank & Small Tank

Cathode Hangers, Large Tank & Small Tank

Another caveat, the process is essentially line of sight from the anode to the part. If you have one part shadowed by another part, it won’t get cleaned well, so you have to arrange dangling objects carefully.

Once the parts are in the tank make one last visual check for potential short circuits. You won’t be able to see through the soup when the process is running. If you’re sure every thing is separated, start the charger and read the current. A good initial amount would be 2/3 rated current as it will increase a bit as the solution warms up. If the current is not high enough, add more carbonate. You can just stir some in, but a better way is to make a hot, concentrated solution in the coffee pot then pour some of that into the tank. If the current is too high you can either lower the voltage or add water to the tank to dilute the carbonate.

Six Gallon Tank

Six Gallon Tank

 

Small Tank in Action

Small Tank in Action

It will take from one to six hours in the tank to get most parts back to an clean state. I usually remove parts every hour and scrub them a bit just to see how the reaction is going. Unlike some chemical methods, it doesn’t hurt to leave the parts in longer than necessary.

After the final scrubbing, one at a time pull the parts out of the rinse pail and thoroughly dry them with towels, heat, and compressed air if there are any holes. Apply oil or paste wax to the bare iron to inhibit future rusting.

 

Other ways to de-rust an iron object. 

Search “electrolysis rust removal” on Google or YouTube. Many chemical methods use a mild acid. Vinegar is popular, it’s usually 6% acetic acid and sometimes salt is added. Naval Jelly works quickly, it contains phosphoric acid. Christopher Schwarz mixes up a citric acid solution, you can get citric acid powder from Amazon. Acid techniques will eat away the underlying metal if the part is left in the soup too long. Electrolysis uses a basic solution which is more iron friendly.

Evapo-Rust is the chemical mentioned most often. Nobody knows what’s in it, the MSDS says “Proprietary non-hazardous chelating agent”. It  supposedly will not attack bare iron if you leave it too long.

Mechanical methods remove rust quickly but run the risk of also removing or scratching the iron. Years ago I restored my very rusted garage sale table saw with Wet/Dry sandpaper lubricated with WD40. Scraping the rust with a razor blade is not perfect but is good for something like an old saw where you want to keep the etch intact. A rotary wire brush in a grinder works quickly but will erode a cast iron part. If you don’t care about flat surfaces and crisp edges go for it.

 

This is an estate sale plane I’m using as a before/after electrolysis demonstrator. The parts were laid on their side in a shallow pan half submerged with a sheet anode in the bottom. I masked the still rusty side with duct tape before scrubbing.

I thought the plane was a generic piece of crap when I bought it but after revealing the Zenith logo stamp and some research, I find it is a very nice tool – Sargent OEMed to Marshall Wells Hardware Co. It’s identical to a Sargent 14C which was only made from 1910 to 1918 and well worth restoring.

Zenith Electrolysis Example

Zenith Electrolysis Example

Zenith Cleaned Side

Zenith Cleaned Side

 

Zenith Before and After Bottom

Zenith Before and After Bottom