Zinc metal spraying is a highly effective corrosion prevention technology widely used on naval vessels, offshore equipment and civil structures such as bridges. The process can be thought of as being similar to galvanising as it results in a protective layer of zinc being bonded to a prepared steel substrate. Somewhat confusingly, metal spraying is known as a “cold process” despite the fact it involves the application of molten zinc. This is to distinguish it from galvanising, which requires the dipping of steel components in a bath of molten zinc at temperatures of 450C with the associated risk of heat distortion. Aside from the impracticability of dipping an entire narrowboat hull into a 450C bath, metal spraying provides similar protection without this risk of heat distortion.
How is all this relevant to the narrowboat owner? Well, we’re used to having to fit sacrificial zinc or magnesium anodes to help protect a narrowboat’s hull from pitting, but we also know how localised this protection can be. Metal spraying effectively turns the entire hull into an anode. This means that when the blacking starts to wear or is damaged by underwater obstacles, the steel is still protected and the risks of pitting are substantially reduced.