Is zinc-rich paint an acceptable way to touch-up damaged galvanized steel?
The simple answer is yes. ASTM A 780 discusses three different methods to repair damaged or uncoated areas of galvanized steel. One of those methods is zinc-rich paint, which is classified as inorganic or organic, based on the material used to bind the metallic zinc dust particles together. Inorganic coatings can often provide adequate corrosion protection in a single coat, while organic zinc-rich paints are often top-coated with another layer of paint. Unlike other paint systems, zinc-rich paints exhibit limited cathodic protection abilities in addition to the barrier protection all paints provide. However, the cathodic protection is largely based on the amount of metallic zinc dust in the dry film and the applicator of the coating. Zinc-rich paints must be constantly mixed in order to maintain a homogenous mixture to promote metallic zinc dust contact once the paint is cured. The cathodic protection provided by zinc-rich paints is considerably less than the cathodic protection provid
