**2.2 Pigment volume concentration**

The physical and mechanical properties of the film and its protective capacity depend on the shape and size of the zinc particles and in addition of the PVC. The critical value (CPVC) is strongly influenced by the ability of binder for wetting the pigment particles.

In this study, PVC values ranged from 57.5 to 70.0%; the variation of two consecutive PVC values was 2.5% in all cases. Preliminary laboratory tests (salt spraying chamber), with values of PVC from 10 to 70% for all formulations, helped to define the range of PVC more convenient to study (Sonawane et al., 2010).
