The PHYNIX gauges allow the non-destructive thickness measurement of coatings and use two different methods: the magnetic-inductive and the eddy-current principle: For non-destructive coating thickness measurement on iron and steel, i.e. ferro-magnetic substrates, the magnetic-inductive principle is used. The magnetic-inductive principle is employed in the models marked with F or FN (F=Ferro-magnetic) e.g. Surfix® FN. The coating must be non-magnetic – for instance, varnish, paint, enamel, plastic, glass, aluminium, lead, chrome, copper, brass, zinc, tin, etc. The eddy-current principle enables the non-destructive coating thickness measurement on non-magnetic metal substrates eg. aluminium, aluminium alloys, lead, bronze, copper, brass, zinc, die-cast zinc, tin. The Eddy current principle is used in models marked with N or FN (N=Non-Ferrous), e.g. Surfix® easy I-FN. The coatings under test must be electrically insulating; for instance, varnish, paint, enamel, plastic, glass, anodizing coatings and ceramics. Coating Thickness Gauge Dealer In Ahmedabad.