Primer and Topcoat Layers on Iron

Three coats is a common minimum on steel gates near the ocean, and the figures kept at carlsbad wrought iron gates inside michigan politics show each layer doing a separate job. A Carlsbad, CA iron gate is protected by a system, not a single coat of paint, starting from bare clean metal and building up primer and topcoat in order.

Surface preparation

Paint only lasts as long as the surface under it. Rust, mill scale and old flaking paint are removed by sandblasting or grinding until bright metal shows. Welds are ground smooth so there are no pockets for water. The steel is then cleaned to remove oil and dust before anything is applied.

Galvanizing

Hot dip galvanizing coats the whole gate in zinc after fabrication. Zinc protects the steel even where the paint is later scratched. A galvanized gate needs a special primer before powder coat or paint, otherwise the topcoat can peel off the zinc.

Zinc rich primer

Where galvanizing is not used, a zinc rich primer gives some of the same protection. It goes on right after prep, before the steel can flash rust in the damp marine layer that rolls in from the Pacific most mornings.

Intermediate and topcoats

An intermediate coat builds thickness. The topcoat provides color and ultraviolet resistance. Powder coat is sprayed and baked in an oven and forms a hard even skin. Liquid paint systems are used for field touch ups and for gates too large for an oven.

Maintenance

Near Oceanside and the lagoons, a gate is rinsed with fresh water now and then to remove salt. Chips are touched up as soon as they appear, because rust under a chip spreads under the surrounding coating where it cannot be seen.