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Joe K · 03-22-2015, 10:40 PM

Phosphoric Acid might be better than any other acidic solutions for gas tank work. The reaction is not fast - but it does work.

I normally use Kleen Strip "Prep & Etch" on all my electrolytically derusted goodies. The electrolytic method leaves Ferric Oxide (magnetite Fe304) which is a black oxide of iron - this ferric oxide is quick to revert back to ferrous oxide (red rust Fe203) hence a need to use SOMETHING prior to painting.

Prep & Etch fills this gap for me. But it works not only on Ferric oxide, but also Ferrous Oxide in the reaction...

2 H3PO4 + Fe2O3 → 2 FePO4 + 3 H2O

Prep & Etch comes as a solution, gallon jugs run about $15, and is a contact sort of chemical reaction meaning one could set up a rotisserie arrangement.

When you're done you can then pour off the excess Prep & Etch, rinse out the tank with water, dry quickly, and then coat in a reasonable amount of time the passivated surface created with your interior coating of choice.

Joe K

03-22-2015, 10:40 PM	#15
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,609	Re: Possible rust remover for gas tank Phosphoric Acid might be better than any other acidic solutions for gas tank work. The reaction is not fast - but it does work. I normally use Kleen Strip "Prep & Etch" on all my electrolytically derusted goodies. The electrolytic method leaves Ferric Oxide (magnetite Fe304) which is a black oxide of iron - this ferric oxide is quick to revert back to ferrous oxide (red rust Fe203) hence a need to use SOMETHING prior to painting. Prep & Etch fills this gap for me. But it works not only on Ferric oxide, but also Ferrous Oxide in the reaction... 2 H3PO4 + Fe2O3 → 2 FePO4 + 3 H2O Prep & Etch comes as a solution, gallon jugs run about $15, and is a contact sort of chemical reaction meaning one could set up a rotisserie arrangement. When you're done you can then pour off the excess Prep & Etch, rinse out the tank with water, dry quickly, and then coat in a reasonable amount of time the passivated surface created with your interior coating of choice. Joe K __________________ Shudda kept the horse.