ISO 2081:2008

ISO 2081:2008 specifies requirements for electroplated coatings of zinc with supplementary treatments on iron or steel. It includes information to be supplied by the purchaser to the electroplater, and the requirements for heat treatment before and after electroplating.
It is not applicable to zinc coatings applied

to sheet, strip or wire in the non-fabricated form,
to close-coiled springs, or
for purposes other than protective or decorative.

ISO 2081:2008 does not specify requirements for the surface condition of the basis metal prior to electroplating with zinc. However, defects in the surface of the basis metal can adversely affect the appearance and performance of the coating.
The coating thickness that can be applied to threaded components can be limited by dimensional requirements, including class or fit.