Rust inhibitor applied at commercial carwashes is another scam like selling spray wax that doesn’t contain any organic or synthetic wax.
Corrosion of automobiles has been virtually alleviated due to vehicle design, method of assembly and coating technology.
After surface prep and phosphate coat, vehicles get dipped in an electro-deposition solution having a 90 percent zinc and 10 percent ferroalloy composition.
After ED, the body is baked in oven at 320 F for 10 minutes to cure the film. Next is underbody coating and seam sealing with polyvinyl chloride. Then comes primer followed by top coat which consists of base coat followed by clear coat.
Some carwash rust inhibitors contain triethanolamine and silicate.
Triethanolamine is a strong base and is used an emulsifier and surfactant (
soap). It is common ingredient in laundry detergent, hand sanitizers, etc.
Triethanolamine is also used a complex agent in electro-less plating and as corrosion inhibitor (anti-rust) agent in immersion ultrasonic testing.
An electro-less deposition process uses only one electrode and no external source of electric current. However, the solution needs to contain a reducing agent so that an electrode reaction occurs.
Downside of this plating process is it’s very slow and cannot create thick plates of metal so process is usually used for decorative arts.
Silicate is largest and most important class of rock-forming mineral.
So
soap is used to wash underbody and leave behind a deposit of silicate which is supposed to prevent rust. LOL