Rust and corrosion occur when metal comes into contact with moisture in the air, causing a chemical reaction. The longer the metal is exposed to moisture, the faster corrosion and rust will spread.
If left long enough, it is only a matter of time before the rust will break through, allowing water to run onto your ceiling and down internal walls. This can lead to an expensive repair bill if ceilings, walls, furniture and carpets are damaged by water and mould. You may also face the risk of damage to electrical wiring and light fittings.
Metal roofs that are over 15 years are very susceptible to rust, especially corrugated iron. Corrosion Control is designed for rust effected metal, the coating converts all the mixed iron oxides, plus hydrated iron oxides, into an iron phosphate which is an irreversible reaction.
Dealing in treating rust is a very risky endeavour for a paint company. There are very few companies that attempt to coat where rust is present without sand blasting or machine abrasion surface preparation. We have trialled many products and are comfortable in only one system, which is explained in detail.
There are many tannic acid based rust converters on the market – Fertan, Neutrarust, Rust Kill, Endrust, Ferronite, and so the list goes on, but they are basically tannic acid solutions designed to pour onto the rust, which then turns black (some versions turn blue), which donates the conversion of the mixed iron oxides and hydrated iron oxides into an iron tannate.
They then apply a zinc rich primer (an extremely dense, oil based primer which contains a high level of dust dust/zinc flake) over the top, followed by a suitable topcoat which, one has to say, is quite a lengthy and extremely costly procedure.
However, in our opionin, there are a number of problems with this approach, including:
- the iron tannate molecule is relatively large and rust can re-occur in the presence of water/moisture and oxygen, plus
- the zinc primers (and subsequent top coats) do not always adhere well to the so called black iron layer.
Our rust converter of choice is designed for application over bad rust only, and the coating converts all the mixed iron oxides, plus hydrated iron oxides, into an iron phosphate, which is an irreversible reaction.
The really beautiful part of this approach is that there is absolutely no interface or distinct transition from the converted layer to the paint film (as occurs with the tannate approach described above) – everything takes place within the paint film itself and the longer the paint takes to dry the better and more complete is the phosphating action.