Restoration Tip: Electrolysis Derusting

[Snowtractor]

...used to work at a rock and roll rotational plastics molding company. We made linear low density polyethylene containers in all sizes. The septic tank was rectangular 2 feet high by 6 wide by 14ft long. With the top cut off it would take a jeep frame no prob. Also the 1200 gallon ( as I recall ) was circular about 5 feet at the shoulder and 8 feet in diameter with a flat bottom. This would take a cab easy. They were about 1000 cdn. We did have the odd piece that didn't turn out or the wall thickness was too small that you could buy for peanuts.
Alternatively a wood crib of appropriate size with a vinyl liner should work. Find someone getting rid of one of those above ground pools and offer to dispose of it for them . Even new they are about 300 bucks for the the small version. Buy it and you have one large caustic tank...just keep the kids out of it.
Sean

[maple_leaf_eh]

You guys are a bad influence. I decided that chemicals and solvents were too much trouble to attack rusted parts, so I made a backyard electrolysis tank. The difficult step was finding washing soda in Canada. It seems to be an America only consumer product. Fortunately, one of the pages I read described how to convert baking powder into washing soda. Bake it at 300 deg F for an hour to drive out an unwanted molecule.

The set up is my 12v battery charger through a leftover 12v battery, jumper cables, some steel plates, a pair of vise grips, some chain and a piece of steel fencepost, rainwater and couple tablespoons of the powder. I used copper wire to hang the parts from the chain.

Yes, it fizzed and yes the surface coatings were softened or slid off. More time in the tank is required. Hours (like overnight) versus 1 or 2 in the evening. Mark II will be bigger and deeper with more steel plates. I will try to rig some permanent hooks on the crossbar. The big question now is how to get good electrical contact for small parts like screws.

[Bob Moseley (RIP)]

Hi Terry - I cannot believe you can't obtain washing soda in Canada. It is the stuff grandmas used before detergent and they used to boil their clothes in a copper. If you can obtain some scrap stainless steel, that is the best anode (+) and use stainless wire to hang everything. Stainless is the best conductor. I don't know how powerful converted baking soda is but with washing soda the ratio is one pound to a gallon.

Re. screws, I have not tried it myself, but maybe if you put them into a stainless sift and connect that to the diode, that may work. If you try that and it works, let us know please.

Bob

[Bob Carriere]

Hi Terry

Best bet is a recycled plastic 45 gal. drum.....cut off the top with a jig saw.... no it will not explode...... allows you to dip bigger peices.... even full axle housing if you do one end then the other....

You will need some cheap yellow nylon rope for hanging things.

Washing soda is readily available in rural Home hardware stores.

Remember the bigger the sacrificial plate is ....the faster it works and the more currant it takes. I used a strip of Stailess steel ( 40 x 18 in) from a recycled restaurant counter..... and curved it to fit inside the barrell..... all around the perimeter.....

Just hang the pieces from the centre.... direct line between SS and parts to be cleaned is best.

I used a mild lye solution.....also from Home hardware..... but it is caustic and the drum can only be dumped on a heavy rainy downpour.

I cheated and made my solution very strong..... it removed rust.... grease and even paint form cast surfaces.....also drained two large batteries in a few hours...... careful with just an average size battery charger.... you can easily over load them..... some will have a safety shut down//// cheaper ones will just fry themsleves.

Really workes wonders......

Small parts...... screws and bolts..... I usually replace them with new stock... but if I had to clean them I would be inclined to screw them in a thin sheet of SS and hang it in the barrell.

SS as a sacrificial plate will not alter color.... but .... if you use a cast iron plate it will color the part being cleaned jet black......

I usually scrub the cleaned parts with a hose and a 3M pad... sun dry.... and spray with diluted Phosphoric acid....... available as metal prep in body shops..... sun dries to a flat grey...... makes for an ideal surface prep for any kind of paint......

Do your process outside..... as the fizzling is actually hydrogen..... as in KABOOM......

Bob

[maple_leaf_eh]

Originally Posted by Bob Carriere

...

Washing soda is readily available in rural Home hardware stores.

...

I used a mild lye solution.....also from Home hardware..... but it is caustic and the drum can only be dumped on a heavy rainy downpour.

...

if you use a cast iron plate it will color the part being cleaned jet black......

...

What brand is the washing soda? Arm & Hammer is "So Clean, Super Washing Soda", and supposedly Walmart, Zellars and Canadian Tire sell it. Pfft! None on the shelf or in their on line catalogues. I was planning on visiting Home Hardware and Tractor Supply Company next.

So you make a solution of lye and washing soda? Sounds like a chemistry hazard in-waiting.

The colour is a good tip. The plates I have are ordinary carbon steel. Colour is not so much an issue because the parts will all get painted over. But removing the old finish and surface rust is secondary to getting the rusted swivels unseized. I will try lying them in a shallow pan with holes for solution circulation. Saddly, most of them are crusty with wood fibre or pits. The hardware is important to the project because some are odd little short and coarse thread woodscrews. [I'm stripping circa 1946 C No.7 .22LR rifle chest hardware from derelict chests for resale on the collector's and No.15 sniper rifle chest reproduction market. Special deal for any MLU'ers who want a set.]

I am going to politely decline using stainless steel. A few of the forums I read talk about hexavalent chromium compounds released by reverse electrolysis of stainless (anyone remember Erin Brockovich?).