A durable layer of zinc coats the steel and forms a physical shield, or barrier, from environmental elements.
A tough atmospheric layer of zinc carbonate is formed at the surface of the galvanized coating when exposed to typical atmospheric conditions.
The zinc carbonate is microscopically thin and is insoluble. Insolubility makes the surface weather resistant and minimizes corrosion.
Zinc reacts with oxygen to form a very thin, hard layer of zinc oxide.
When this surface has access to freely moving air in normal atmospheric exposure, the surface reacts with rainfall or dew to form zinc hydroxide.
As the surface dries, the zinc hydroxide reacts with the carbon dioxide in the air and is converted to basic zinc carbonate.

Sacrificial Protection:
Steel and zinc both react with the environment, but zinc reacts slightly faster. When exposed to the environment, zinc reacts first, and leaves the steel unaffected - that is, the zinc is sacrificed to protect the steel.

Sacrificial protection prevents corrosion of the base steel of exposed areas such as cut edges, punched holes and accidental scratches.
It occurs when two dissimilar metals are in contact and are in the presence of an electrolyte (the air's moisture).
Since zinc is more anodic than steel it corrodes preferentially to the iron in steel.

Galvanization

Carbon steel sheet coated with zinc and small iron-zinc-aluminum alloy bonding layer on both sides by the continuous hot dip process.
Coating Weight = Minimum 0.90 oz./sq. ft. of zinc.
Features include:
- Excellent Formability
- Extreme Heat Resistance
- Excellent Sacrificial Protection
- Unmatched Paint Adhesion
- Strong Atmospheric Corrosion Protection
- X-Ray radiation is used to verify zinc weight over the substrate.
- As technology has advanced towards improving the quality of galvanization, galvanized metal usage in North America has increased considerably. From 1980 at 7.3 million tons to 1995 at 14.5 million tons.