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Since my tank is particularly rusty i've been looking at methods to "de rust" it. I came across this thread https://www.mopedarmy.com/wiki/Removing_rust_from_a_gas_tank that had several methods for tank "cleaning" and found it very interesting. Let me start by saying i've not tried any of these methods and can't vouch for any of them. I've seen most all of these methods listed in various places before except the electrolysis method. Has anyone on the forum (or anyone you know) ever tried this method before? I like the sounds of it for two reasons; 1) it seems like it produces less toxic mess you have to dispose of, in fact they state you can pour it on your grass (hmm, i wonder) and 2) it doesn't eat metal away like all the other methods. What are your thoughts on the electrolysis method?
 

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Last two tanks I did I put a short length of chain with a bunch of small bolts threaded through it in the tank and swished it around with hot soapy water for 20 minutes. Then rinsed thoroughly with hot water. Then I filled it with evapo rust, which is also supposedly non toxic and reusable. I let it sit for 5 or so days, moving the tank around to ensure all surfaces were exposed to the evapo rust. Then I drained and rinsed several time with methyl hydrate. Let it dry briefly and filled with gas. Both time this removed all rust.
 

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Electrolysis has been used many times by members of this forum. As I understand it, the trickiest part is getting the electrode inside the tank located where it is close enough to the rusty surface for the rust to move to it but it can't make contact with the inside of the tank.

I haven't tried electrolysis for the inside of a tank but I did experiment with it a few years ago for general rust removal, using this page for reference Rust removal by electrolysis It did remove the rust but unlike chemical rust removers that dissolve the rust and carry it away, electrolysis transfers the rust from the part to the electrode and I found I was spending almost as much time & effort mechanically removing the rust from the electrode as I would to just remove it from the part in the first place.
BTW: One of the parts I tried de-rusting with electrolysis was an exhaust header for my winter machine, the plan being to then zinc plate it so the zinc would fill the holes left in the chrome and keep it from rusting again the next year. The problem is that the electrolysis removed the chrome plating as well as the rust and zinc plating doesn't hold up on hot parts so by about this part of the winter it was mostly bare rusty steel and by spring there was virtually no zinc left.
 

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I also use Evaporust but have learned to get out most of the big chunks and flakes by whatever method works best so as not to waste the solution attacking loose rust, but instead attacking all the surface light rust, which is what you need to do to get shiny metal, I mean, why waste spendy rust removal product on the big loose crud that can be removed by other means ?
 

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I have used chain/screw/bolt method, evapo rust, electrolysis, solvents and vinegar. Everything works to varying degrees but I think that straight white vinegar left in the tank for quite awhile seemed to work best for me, it is also really cheap.
 

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POR-15 is what I used. That nice thing is it also plugged some small pin holes that showed up after removing the rust. Be leak and rust free for 10+ years now.
 

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The motorcycle POR-15 Kit

Make sure you can read and follow instructions. Otherwise you will be wasting your time.
 

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Most important with POR 15 is to making frickin sure it's Dry before pouring in the coating.
 
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