Rust converter

Rust converters are liquid mixtures, which are used for reversal or termination of the oxidation process of iron. By the chemical process of the grate (FeOOH or iron ( III) oxide ) is usually converted to a stable iron ( III) compounds. In particular, the converted material does not form porous structures more, keep the moisture and thus promote further corrosion.

Rust converters are often used in the repair of cars, color mixtures even with heavy equipment, boats, fences, etc.. To reach a lasting protection only if loose rust has been previously removed, eg by brushing, grinding or sandblasting. Rust Converter can not convert them back into the metal rust, treated surfaces are not reflected metallic shiny, but dull dark gray.

Rust converter today contain almost all phosphoric acid or phosphate as the active ingredient. In the application of iron ( III) oxide to the water, and iron ( III ) is reacted phosphate. The iron phosphate layer is non-porous, such as rust (a mixture of different iron oxides ), but resistant and paintable.

Individual products work on the basis of tannins. Previously they took heavy metal oxides such as that of lead ( minium ) and cadmium as well as chromates. These form stable iron oxides, in the case of tannin and water-soluble iron - tannin compounds. Heavy metal compounds are predominantly harmful to the environment.

In addition to the actual active ingredient rust converters often contain various auxiliaries and additives to aid the process of Rostumwandelns. For use come as surfactants, which provide a better wetting of the surface of the workpiece to be treated. Further excipients serve as reaction accelerators or degreaser. Frequently commercially available rust converters are also mixed with primers or directly with a topcoat.

In principle, any liquid containing phosphoric acid, act as rust converter, for example, cola. Because of the low acid content is here but the effect restricted.

A problem in the application of rust converters - at least for those who remain on the workpiece - is that the reaction of rust and acid proceeds stoichiometrically; so it must be brought together in a specific ratio rust and acid. However, this is practically impossible, so either rust or acid remains. In both cases, the desired effect, namely a proper basis for the coating is not achieved.