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Old 10-23-2007, 06:23 PM
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81xsproject 81xsproject is offline
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Rust Removal by Electrolysis

Rust Removal by Electrolysis
By 81XSproject

The following info and pics are quoted and linked from the very smart folks over at the www.650rider.com forum. All credit is given to them.

This is an excellent way to remove rust w/o any harsh chemicals and works very well. The only things needed are; water, Arm and Hammer WASHING Soda (not baking soda; sodium carbonate vs. sodium BIcarbonate respectively),

some steel wire (coat hanger, bailing wire, I even used a hack saw blade), and a dumb battery charger. When I say dumb, I mean it can't have any auto shutoff, trick charge, battery tending features. I went down to the pawn shop and got a 6 amp 12 volt charger that is simply on or off.

If you can't find washing soda (aka soda ash, laundry soda, sodium carbonate, carbonate of soda, etc.), you can get it at pool and spa supply stores being sold as pH increaser. It is very inexpensive because at these stores you can get smaller quantities.

The mixing ratio is ~ 1/2 cup soda to 5 gallons of water.

A little background on how electrolysis works (see actual photos below):
It's very simple really. As current passes through an object it moves from negative to positive, so what you are doing is passing a current through the rust on the tank, which breaks its bond, and the rust then flows and attaches itself to the positive charge on the sacrificial anode. Or at least it releases the rust from the tank and floats around in the washing soda solution. The idea with the sacrificial anode is to insure that it does not touch the tank anywhere, you must insure that it only comes in contact with the washing soda solution or you will have a direct short.

Removing rust from a fuel tank:
Pull the fuel tank and drain the fuel. Remove the petcock and wash out the tank with lots of water. Fashion a cover to block the petcock orifice. I used a strip of 1/8" aluminum and used an old inner tube as a gasket. Riders have asked "can I leave the petcock in?". The answer is no. Although aluminum can be cleaned with electrolysis it only takes a matter of minutes. Whereas with the tank it takes days. By the time the tank is clean the petcock would be no more.

I set the tank on a piece of carpet and blocked it up to get it as level as possible. I then filled the tank with the washing soda solution. Then I took a coat hanger and fashioned the sacrificial anode. You say what???? Ok this is the trickiest part of the procedure. (Check out Clay's photos or my illustration)
For my project I found a nice little plastic cap and drilled two 1/8" holes in it about 1" apart. I then took the coat hanger and bent it over and over until I had four loops on one end that spread about 1" when grouped together (Fig. 1).

Fig. 1

Think about the business end of a fork that you eat with, that's what it should look like. Then about 4" back from the business end of the fork make a 90-degree bend in the two wires and run them up through the plastic cap. Put the sacrificial anode into the tank and spin it around to insure the anode is not hitting anywhere on the tank (no short circuits) (Fig.2).

Fig. 2

Then using a 12-volt battery charger hook the positive lead to the sacrificial anode and the negative lead to the fuel tank . I used the mounting flange that sits under the seat (see figs 3 and 4 below). Let the fuel tank cook for several days. Mine took three days. I pulled the anode twice a day and cleaned it with a wire brush. I have a small battery charger so it may take less time with a larger charger. Once you have determined all of the rust in gone in the fuel tank, dump the electrolysis solution into a plastic bucket and save it. You can use it over and over again. I alway make about 5 gallons at a time and just add water as it evaporates out.

Fig. 3

Fig. 4

Remove the petcock block and wash out the tank with lots of clean water. I then put in two bottles of cheap rubbing alcohol and swish it around to displace any water in the tank. There is standard 70% alcohol, and there is also 90% alcohol, very close to Denatured, but much cheaper, and has much less water than the 70% stuff. I then set up a hair dryer and ran hot air through the tank until I could no longer see any moisture. Next you have to decide if you are going to coat the tank or leave it bare. I left mine bare at first but have since coated the tank. I used NAPA automotive tank sealer, and it has worked very well. My tank has now been on my bike for two seasons with no problems.

Rusty parts may also be cleaned this way by suspending them in a bucket
(Fig. 5).

Fig. 5

End quoted material from 650rider.com

Additional Notes
-I had a very old and dirty tank. With a 12 volt 6 amp charger, it took almost a week and I went through 1 coat hanger anode, 2 wire paint can handles, and 1 hack saw blade before all rust was removed.

-Acetone or denatured alcohol would probably work a little better for the final rinse.

-Unless it is YOUR blow drier, I would recommend not using it for this. Don't do like I did, and ruin your wife's . However, had I been a little smarter, I would have used the warm or cool settings on the drier and probably not have burnt it up. Wife...
not so happy .

-Don't get too much soda powder on yourself. I read out in cyberspace that the stuff has a pH of around 11. This is a very ALKALINE solution. Alkalis actually can cause more severe burns than acids! Acids are neutralized very quickly with proteins, but Alkalis are not, and can keep on chemically burning. They are equivalent to BLEACH, or very strong soap=LYE! And if you think about how long it takes to rinse/wash soap from your hands,you can appreciate the difficulty in neutralizing it, especially if it gets in your eyes! That's why they always tell you to flush the eyes for 15 minutes FIRST, then contact your Emergency Service! So...be sure to use Eye Protection, as well as GLOVES! You have been warned

-I used a rubber patch and a metal backing plate and bolted them in place of the petcock. Worked great.

-I stopped the process the first time I pulled out the anode and it didn't have any rust accumulated on it.

-When checking/cleaning off the anode, make sure that moisture isn't building up on your rubber/plastic anode insulator and completing the circuit from the anode directly to the tank. I wiped mine dry every time I checked.

-I feel like I am forgetting something, but lastly, I think you might even be able to throw some rusty parts in the tank to clean at the same time. But, I am not sure if the science on that is correct or not?
'81 XS1100 SH

Melted to the ground during The Valley Fire

Sep. 12th 2015

Old 11-17-2007, 10:59 AM
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81xsproject 81xsproject is offline
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Join Date: Nov 2004
Location: Fortuna, CA
Posts: 3,185
I wanted to add a tip and a story from another forum to this tip. It is a good tale that has a safety lesson mixed in.

The tip is that a long bolt makes a great anode as it lasts a whole lot longer and has a comparable surface area.

Here's the story:
For the last two weeks I've been de-rusting my CB750F tank with the battery charger. It's working.

Today however, after cleaning the electrode for the umpteenth time, I failed to address the loss of electrolyte, leaving about a half inch of space clear in the tank. This is in an outdoor area. But today there was no wind to dissipate the Hydrogen in the tank while it was open. Anyway, the electrode "just" fits in the tank. If it is not placed correctly, it hits the inside of the tank, shorting out the battery charger. It's easy to tell if you need to reposition it as the current meter pegs. And, you readjust the electrode and start it up again. So, it isn't usually a big deal if the tank is full.
Mine wasn't and the spark inside the tank lit off the hydrogen/oxygen mixture. Boom!

I could see the entire tank expand and the 1/4 brick I had holding down the electrode cap over the filler hole shot into the air a couple inches from my head. Then right back down onto my previously undented tank. Roll Eyes It's got a new crease in the tank top, too. Though its in an area that needs brazing, so it won't be too difficult to fix.

Anyway, I determined today that my heart will still beat quite fast!

If any of you are doing the electrolysis de-rust thing, be sure to keep the tank full so the hydrogen will not linger in the tank. Lesson learned.

Be careful out there.

'81 XS1100 SH

Melted to the ground during The Valley Fire

Sep. 12th 2015


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