Zinc Coatings

Zinc protective coatings are used for long-term protection of steel substrates. They serve as a sacrificial coating that concentrates the electrical potential of a corrosion cell onto the zinc itself instead of the steel it's protecting. This is known as cathodic protection, which is a fail-safe method of protecting steel from oxidizing. Other forms of cathodic protection include galvanizing and connecting anodes to steel that attract the electrical potential in lieu of the steel itself. Anodes are simply metals that will attract the electrical potential (and thus corrode) easier than the steel they are meant to protect — which is exactly what zinc coatings offer.

Zinc coatings include the following:

Inorganic zinc ethyl silicate (Carbozinc 11HS, Ameron Dimetcote 9HS)
Moisture-cured inorganic zinc polyurethanes (Tnemec 90-97, Wasser MC Zinc 100)
Water based inorganic zincs (Sherwin Williams Zinc-Clad XI, Carbozinc 11WB, Ameron Dimetcote 21-5)
Zinc rich epoxies (Carbozinc 859, Devoe Cathacoat 302H, Amercoat 68HS)

Prior to installing any zinc coating it is critical to thoroughly clean the steel through abrasive blasting. This abrasive blasting process removes salts and other contaminants that can interrupt the electrical connection between the zinc and the steel. Even zinc-disbursement and proper film thicknesses are also very important to ensure a long-lasting coating. Finally, since zinc protective coatings are very porous, successive topcoats need to be applied properly to achieve a pinhole and bubble-free surface that will protect the zinc from weathering and external elements.