R A Francis, R A Francis Consulting Services
It is generally accepted that, for maximum protection, paints must be applied to surfaces which are entirely free from rust and other contamination. This is especially true of modern high performance coatings such as epoxies, inorganic zinc silicates, etc where abrasive blasting to a high standard is usually mandatory. There are, however, situations where it is not possible to completely remove all rust from the surface for design, economic, safety or other reasons. There has therefore been much research into treatments for rusted surfaces to avoid the need for such critical surface preparation. A large number of products have appeared on the market for such purposes although it is generally agreed that the protection achieved is nowhere near that attained if a rust-free surface is used. However, there is certainly a market for such products, especially in the consumer, or DIY market.