After galvanizing, the continuous zinc coating is physically wiped using air knives to produce a uniform coating across the width of the strip. The uniform coating consists almost entirely of unalloyed zinc and has sufficient ductility to withstand deep drawing or bending without damage. A variety of coating weights and types are available, ranging up to just over 3 mils (76 µm) per side. One of the most common zinc coatings is Class G90, which has 0.9 oz/ft2 of zinc (total both sides) or about 0.80 mils (20 µm) thickness per side. Continuous sheet galvanized coatings often get confused with batch hot-dip galvanized coatings because the term “galvanizing” is used interchangeably. The table below compares the available coating grades of continuous and batch hot-dip galvanizing and their corresponding coating thicknesses. Zinc coating thickness is proportional to the service life as evidenced in the Time to First Maintenance Chart. Continuously galvanized sheet steels are used to make cars, appliances, corrugated roofing and siding, and culvert pipe. The coated product can be suitably treated for painting, which will increase the service life. Because of the thin coating, this product normally is used for interior applications or where exposure to corrosive elements is mild.

See Also: Zinc Coatings Publication

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