Zinc Painting Production Process
Zinc-rich paints typically contain 92-95% metallic zinc in the film of the paint after it dries. The paints are applied by brushing or spraying onto steel cleaned by sand-blasting. While white metal blasting (NACE No. 1) is preferred, near white (SSPC-SP 10) or commercial blast cleaning (SSPC-SP 6) are acceptable.
When the zinc dust is supplied as a separate component, it must be mixed with a polymeric-containing vehicle to provide a homogenous mixture prior to application. Application is usually by air spray, although airless spray can also be used. The paint must be constantly agitated and the feed line kept as short as possible to prevent settling of the zinc dust. Uneven film coats may develop if applied by brush or roller, and cracking may occur if the paint coating is applied too thick. Zinc-rich paints are classified as organic or inorganic, depending on the binder, and must be applied over clean steel.
Zinc Coatings Publication
© 2020 American Galvanizers Association. The material provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel. This material provides general information only and is not intended as a substitute for competent professional examination and verification as to suitability and applicability. The information provided herein is not intended as a representation or warranty on the part of the AGA. Anyone making use of this information assumes all liability arising from such use.