[AJD] Phosporic acid and cleaning a gas tank

[Eric LaCruze]

Kyle;

The acid removes the rust, but does nothing to prevent future rust. You 
need to de-rust, then ASAP coat the metal with something to prevent new 
rust from forming on the fresh metal. I don't have a lot of answers for 
the coating, we used to use stuff called Kreem on our motorcycles, but 
it was hard to get right even on those small tanks.

Eric

Kyle Sands wrote:

> I would never have imagined it would be so difficult to find phosphoric acid.  I called all over town asking for it by name and also under names such as ospho, metal prep, or metal etch.  Nobody had anything, but more likely, I don't think anybody had a clue what I was aksing for...
> 
> In desparation, I went to a fleet store and looked through all their cleaning products to see what I could find.  I finally found a product called rust destroyer or something like that and it listed the active ingredient as phosphoric acid.  It cost my 8 bucks for 32 oz. but I didn't care.
> 
> I had cleaned out my gas tank using muriatic acid to eat away all (or at least most) of the rust inside.  I then washed that solution out with a lot of water and poured in this rust destroyer stuff.  I sloshed it around, let it sit, sloshed it around again, let it sit, and did that several times leaving it in overnight.  I poured it out the next day figuring my tank was ready - sealed and protected from future rust.
> 
> Wrong!  I opened it up a couple days later and rust is starting to form on the walls and on the little metal dipstick.  What's going on?  I thought phosphoric acid was supposed to coat the metal with a protective coating??  Am I wrong, or did I mess up somewhere?????
> 
> Kyle Sands <>< Alexandria, MN
>