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Time to remove the Evapo-Rust and clean out the ultrasonic cleaner after cleaning the Model B transmission parts
Sludge and residue in the bottom of the ultrasonic cleaner
Automotive American – Classic Vintage & Modern
Time to remove the Evapo-Rust and clean out the ultrasonic cleaner after cleaning the Model B transmission parts
Sludge and residue in the bottom of the ultrasonic cleaner
first I should tell everyone I’m not a chemist or a chemical engineer. Evapo-Rust utilizes a chemical conversion known as Chelation. Rust is the product of oxidation of ferrous metals, and the oxidation is what we know as rust. Chelation is the reverse action of the oxidation process.
Phosphoric acid [remember Naval Jelly?] and other acidic de-rusting processes basically coat the oxidized steel or iron to chemically stop the oxidation. Mechanical processes like sand blasting physically remove the rust along with some of the good metal. Uther chemical systems including Redi-Strip, where the metal is dipped in a tank, eat away at the oxidation, down to the bare metal.
High-solids paint like POR-15 are able to create a full cover over the rust, depriving it of the air needed to continue rusting, but it only covers, not removes, oxidation. [Rust requires 3 things to make it work: ferrous metal, oxygen [air] and moisture.]
The Chelation process is different. It actually converts ferrous oxide back to base ferrous metal. It does have some limitations, if the oxidation is too thick it may not be able to convert all the oxides back to base metal. Cast or forged iron and steel, if coated with a light amount of rust, can benefit from the Chelation proces the best, and actually return that oxidated metal to fresh metal again [ready to rust again as well!]. If the steel or iron has a thick coating of rust, it might be better to remove the heavy rust coating [often flaky] prior to using the Chelation agent.
When you see those freshly de-rusted parts in the photos here, the former light coating of rusted metal is still there, it’s just been chemically converted back to iron or steel. This is why there is little evidence of rusted metal sitting at the bottom of the tank. Most of that is from solvents & dirt that were not removed 100% before Chelation.