A number of additives are used in papermaking, from calcium carbonate used as a filler to a variety of minerals and latex added to the surface coating to improve brightness, gloss and printability. The selection of the additive depends on the surface finish required and the final use of the paper. Colored papers require the addition of a pigmenting agent. The particle size of all these materials affects surface finish, color strength, and mechanical properties. Smaller particle size provides a smoother surface and better coverage per unit of additive.