Coating mass is the single most misunderstood figure in coated steel. One supplier quotes Z120, another quotes Z60, and without the measurement basis the two numbers cannot be compared at all.
The basis matters because standards state coating mass differently: some express the total on both sides together, others express what a single side carries. A coil described as Z60 per side is a heavier product than one described as Z60 in total, and the difference shows up in both price and service life.
Confirm four points in writing: the coating type, whether the figure is per side or total, the surface finish, and whether the coating weight record will be attached to the mill certificate. For prepainted material, add the top coat thickness and the RAL shade.
Every coated order we ship states the coating mass with its basis, records it on the certificate, and confirms the colour before production starts, so the coil you receive can be checked against the coil you ordered.