[sdiy] products for rust removal - the joys of phosphoric acid

[aankrom]

I used to able to find this cheap-ass toilet bowl cleaner that used 
phosphoric acid. While being a lousy toilet bowl cleaner, it was a great 
rust remover. Plus I noticed that when I soaked a rust bespeckled 
galvanized chassis, the phosphoric acid would react with the zinc, 
giving the WHOLE chassis this nice battleship-grey finish. You couldn't 
even tell the rust had been there unless it was really pitted. But I 
can't find it anymore. I suppose it's a combination of the the toilet 
bowl cleaner being lousy at its job and the fact that phosphoric acid 
can contribute to algal blooms and such. So I rediscovered Naval Jelly 
and the hassles that come with it. It works fine on bare metal rusty 
surfaces. But it eats paint and sometimes leaves this residue that's as 
much of a pain to get off as the rust. I should try pouring a glob into 
a tub of water and try my galvanized chassis soak. Maybe diluting it is 
the answer.
The effect phosphoric acid has on galvanized steel is similar to a 
technique to treat metals on motorcycles and such called "Gibsonizing" 
but try to Google THAT and get hits pertaining rust-removal. Seriously - 
even you try gibsonizing+rust+zinc, etc.

I was wondering if anyone else had some tips for products that remove 
rust. Ones that are stronger than citric acid. Something like Naval 
Jelly is a plus.

Anthony