A surface that is sufficiently smooth will be glossy. To reduce the gloss we must roughen the surface and break up its smooth outline. In pigmented finishes this is usually done by increasing the number of pigment particles present in the paint and hence, at the surface of the paint.

The protruding particles break up the smooth outline. In varnishes and clear finishes, we cannot do this and reduction-of gloss to satin or matt finishes is usually obtained by additives (translucent pigment).

Either a few per cent of fine particle silica are used, or else an insoluble wax is dispersed in the finish and floats to the surface during drying. The silica being an extender which is transparent in the finish and its high oil absorption reduces the gloss more effectively than larger quantities of pigment.

In many cases the silica, like the wax tends to float to the surface, as larger aggregates containing many particles. The air trapped in the un-wetted spaces between the particles reducing their density and allowing them to rise to the surface.

When wax is used, only small quantities are needed to give very smooth feel to the finish. Polyethylene and polypropylene waxes are particularly efficient and being relatively high in molecular weight does not impair the heat resistance of coatings.