Q. What is the proper gage to measure coating thickness of zinc plating? Also, what gage is the right one for powder coating and manganese phosphating? P.J.
A. Zinc is usually plated over steel substrate, so a regular coating thickness gage employing a magnetic principle will work. Electroplating the zinc results in thicknesses of only a few microns, and a gage with a microprobe and magnetic principle works well for that. Hot-dip galvanizing puts the zinc on much thicker, and probes used by powder coaters work best with a standard probe and magnetic principle. This same gage works well for powder coating.
If you want to measure powder on zinc plating, the same gage will work, but you must be sure that it is zeroed on the zinc surface first.