Rust converter

Commercial rust converters are water-based and contain two primary active ingredients: tannic acid[1] and an organic polymer.

Tannic acid chemically converts the reddish iron oxides into bluish-black ferric tannate, a more stable material.

[citation needed] Some rust converters may contain additional acids to speed up the chemical reaction by lowering the pH of the solution.

A common example is phosphoric acid, which additionally converts some iron oxide into an inert layer of ferric phosphate.

Rust converter is usually applied to objects that are difficult to sand blast, such as vehicles, trailers, fences, iron railings, sheet metal, and the outside of storage tanks.