The above pictures illustrate an obvious defect and solution: When metal has corroded into deep pits, or worse still into perforations then complete removal and replacement is the only satisfactory solution.

However, the decision when to replace metal is rarely straightforward. Even the most sound looking old car will have areas of surface rust unless it has been painstakingly restored. The picture on the left shows the underbonnet area of a Morris 1000 during the replacement of a chassis leg and an area of the Offside wheelarch. The rest of the metal certainly doesn't warrant replacement but there are areas of red surface rust which will continue to corrode unless something is done. The welding process has also started further oxidation on the surface of the metal which will eventually break into rust underneath the paint unless it is suitably prepared beforehand.

The picture on the right shows the same vehicle after the underbonnet area has been thoroughly cleaned to remove all traces of visible oxidation and then chemically treated with a Phosphate based system. Simply removing the visible rust is not on it's own sufficient to rust proof the metal: Once metal starts to corrode it is no longer in a state of equilibrium and corrosion will continue unless this equilibrium is chemically restored. Phosphate based systems are amongst the most effective solutions for ferrous metals. Understanding the correct choice and application of the chemical treatment is vital to ensuring complete treatment of the metal and subsequent adhesion of the chosen paint system. We use differing Phosphate treatments and application methods depending upon the severity and location of the corrosion and the paint system which is to be applied.