Various ASTM and/or other specifications require different weights or thicknesses, so it is imperative to convert all coatings to a common denominator for comparison. While coating densities for some types of zinc coatings are nearly identical, others differ considerably. The coating densities, in terms of thickness required to equal 1 oz of zinc per square foot of surface, are:

Coating Thickness to reach 1 oz/ft2
Hot-dip galvanizing (batch or continuous), electroplating, zinc plating 1.7 mils (43 µm)
Metallizing (zinc spraying) 1.9 mils (48 µm)
Mechanical plating 2.2 mils (55 µm)
Zinc-rich paint 3-6 mils (75-150 µm)

Each of these thicknesses, representing the same weight per unit area of zinc, would be expected to provide equivalent service life; i.e. 1.7 mils of hot-dip galvanized would give about the same service life as 2.2 mils of mechanical plating or 3-6 mils (depending on the paint formulation) of zinc-rich paint, assuming bond strength and edge protection are not factors.