extenders and other minerals such as white fillers and matting agents at higher doses to generate pores within the film. This consequently enhances light scattering due to the low refractive index of air (R. I. ~ 1). According to Mie theory, scattering is proportional to the number of particles and is optimised for a given particle size [1]. This is valid for TiO and also air. Both the number and size of air voids generated in a dry coating therefore influence the dry hiding. Figure 1a illustrates an improved whitening and scattering effect generated by a larger ...