Basis 70, for instance, means that 500 sheets of book paper will weigh 70 pounds. The basis weight is often referred to as sub or substance weight. There is some correlation between brightness and whiteness. Other factors, such as gloss and shade, also play a role in the perception of whiteness. Coated Paper Coated papers have a surface treated with clay or some other pigment and an adhesive mixture.
Coated papers are thinner, smoother, and have better ink holdout for sharper print quality.
Coated papers also have less show-through than uncoated papers. Coatings can range from a matte finish to a high-gloss finish. Fully coated papers use a heavy layer of coating material that smoothes out the hills and valleys of a paper surface, creating a uniform print surface. Film-coated papers feature a very light coating that does little to smooth out the paper's surface. Filler Material, generally a mineral, added to pulp in order to enhance brightness or opacity.