[TR] rust removers recommendations

[Randall]

> It does a pretty effective job of arresting 
> rust but it 
> leaves a residue of iron phosphate

What's wrong with a coating of iron phosphate?  I thought it was supposed to
be a Good Thing, as it helps inhibit future rust and also helps paint
adhere.  For example, phosphoric acid is the main ingredient in DX579 Metal
Prep, which is used to etch the surface just before applying primer.

> This is a hazardous 
> material in that it is 
> an acid and must be handled as such.  And you must rinse that 
> off, too.

Phosphoric acid is not very hazardous, though, and in fact is an ingredient
in many soft drinks.  After reacting with rust, you have iron phosphate and
water.

-- Randall