http://www.evapo-rust.com/product-info/faqs/Acids "eat at" iron oxide on the surface of a part and send the oxygen off into the liquid in one direction, and the iron in another.
( scientificly: the acid helps the iron and oxygen ions dissociate from the metal surface)
Strong acids can do this with iron atoms alone. Strong acids continue to "eat" iron atoms off the metal surface, turn them into ions, and these ions wander off into the liquid. All the metal could eventually disappear this way. The original part would disappear eventually.
Evaporust is different.
It "buddies up" to the rust molecule at the metal surface and carries the still combined iron and oxygen atoms away together into the liquid.
This process has a special name: Chelation.
The special difference is that once Chelation has got the iron oxide rust off the metal surface it does not continue and remove pure iron. The original part will not disappear.
The above descriptions are simplifications. Please do not report me to the Chemistry departments that might have me tarred and feathered.
