http://www.garagejournal.com/forum/showthread.php?t=69793
Hello-
I thought I would share a few results of some experiments. After searching the web, it appears that Evapo-Rust and similar products are actually chelation agents. These are compounds that bind tightly to oxidized iron and pull it into solution. I could go into detail, but this is posted elsewhere. In any event, one of the best chelation agents out there (rumored to be the active ingredient in E-R) is ethylenediaminetetraacetate or EDTA. One can purchase this pure in bulk (for example from sigma aldrich). Get EDTA, not its disodium salt. It is around $110 per kilogram. I made up about a 5% solution, and adjusted the pH to 9.0 with sodium hydroxide pellets (dangerous, know how to handle). Even extremely rusted wrenches were remarkably cleaned with this very cheap solution. After about a day in the solution with an occasional mild scrub with a scrub pad to remove bulk rust, they were essentially rust free, and ready for passivating (some kind of treatment to prevent flash rust of pure iron crystals that form on the surface of the tool during this process). One can use WD40, or microcrystalline wax. It is probably not superior to electrolysis, but is really easy. The solution is relatively non-toxic. About 80 million kilograms of EDTA are synthesized annually. Some people even take minute quantities as a (probably quack) cure-all. That being said, it does break down into some compounds with some pollution potential. Another compound with potent chelation properties is EDDS (ethylenediamine NN Disuccinic acid). This compound is much easier on the environment, but is also much more expensive ($400 for one liter of a 35% solution), and I have not yet tried this on a rusty wrench.
