Rust is one of the most common problems with older vehicles, and while rust prevention is the best practice, products like a commonly available rust converter may help to remove the beginning traces of the problem. While the advanced stages of rust may sometimes only be remedied by excessive cutting and welding or even replacement of the affected panels, surface rust and minor cases of pitting may be a prime candidate for a rust converter. Just how exactly these rust converters work however, is the result of several interesting chemical reactions.
The Nature of Rust
Rust, also known as Iron Oxide, is formed by a chemical reaction in which Iron oxidizes when in the presence of Oxygen and water or excessive moisture. Iron Oxide lacks many of the structural characteristics of the original Iron material and will continue to spread deeper into the material. If left alone, rust will almost always result in total failure of the panel or component affected. It should be noted that once Iron has been converted to Iron Oxide, it cannot be changed back. Thus, even if converted to a more stable compound as in the case of a rust converter, there will still be a permanent decrease in the physical properties of the component affected.
How a Rust Converter Works in Theory
Rust converters are designed to neutralize existing rust as well as prevent it from advancing its damage. The active ingredient in most rust converters is Tannin, in the form of tannic acid. This tannic acid combines with the Iron Oxide to form a more stable compound called Iron Tannate, which is typically black in color compared to the reddish color of rust. Many commercial rust converters will include both a polymer to act as a protective layer, and an additional acidic compound designed to accelerate the chemical processes related to the tannic acids. One such acid, known as Phosphoric acid may also work as a rust converter itself, by reacting with the Iron oxide and converting it to black ferric phosphate.
Limitations and Function in Practice
While scientific evidence exists proving that applying tannic or phosphoric acid to Iron Oxide does indeed promote the formation of Iron Tannate and Ferric Phosphate respectively, this same evidence shows these formations tend to only occur along the outer most layers of the metal. What this means is that while rust converters may be effective at removing light cases of surface rust, their ability to penetrate and convert deeper deposits of rust may be limited to non-existent. This means that for advanced cases of rust, these converters may be useless. In addition, any metals treated with a converter as part of an auto rust repair regiment should be cleaned and coated with a protectant as soon as possible after the converter has done its job. Otherwise, surface rust may quickly regain a foothold on the metal.
When it comes to rust, the best approach is one of prevention rather than treatment. There are many different methods to preventing rust that can be quite effective, but once rust has become a problem, it can be very difficult if not impossible to fully remedy the problem.