The following is the process I used to remove rust from the inside of a motorcycle gas tank.
All the information herein can be (and was) found on the internets. This was my first foray into electrolysis and I supplemented my newly gleaned knowledge w/ much caution.
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Step 1: Materials & Tools
What you need:
- A gas tank with rusty innards
- Some Arm & Hammer Super Washing Soda
- A sacrificial anode made of steel (but not stainless) or iron
- A battery charger
- Some scrap wood
- A bucket
Step 2: The Sacrificial Anode
The sacrificial anode must not come into contact with the gas tank.
The anode itself is a piece of steel rod formerly used to hold up a plant (I think). Stainless steel will produce toxic substances during this process, so steer clear of it.
To suspend it inside the tank I fashioned a collar of sorts out of some scrap wood. The rod is bent above the collar to keep it from sliding into the tank and bent below to thread the narrow clearance between the underside of the top of the tank and top of the bottom ridge.
Note the amount of rod above the collar. This is a mistake. The extra weight actually pulled the bottom part of the rod into contact with the top of the tank when the battery charger was later connected.
Step 3: The Electrolytic Solution
Fill up the bucket with enough water to fill the gas tank.
For every gallon, add a tablespoon of of the Arm & Hammer Super Washing Soda. Adding more doesn't speed up the process, but I haven't read anything to suggest more soda will impede it either.
When all the soda is dissolved, top off the tank with the solution. Be sure to put a cork in any holes in the bottom of the tank (for petcock etc.)
Step 4: Hook It All Up
Attach the negative lead from the battery charger to the tank.
Attach the positive lead to your sacrificial anode.
Turn on the charger. I dialed mine to the 10amp setting. Leaving the charger on at the 50amp setting for the extended periods of time required for the process caused the charger to overheat and turn off. A nifty safety feature.
(See the tape? Yep. It's there to keep the anode from tipping out of place.)
I let the set up run for 8-10 hours at a time between check-ins.
Step 5: Results
In between electrolysis sessions I would extract the sacrificial anode and clean it. Basically knock off the accumulated rust, dry it and sand it down a bit to remove the more stubborn bits.
I also replaced the electrolytic solution each time.
It definitely worked, but I wish I'd taken the time to do several more sessions.
As it is, I'm not planning on keeping the tank, so I wasn't too concerned at the time.
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