ANSI/TAPPI T 1214 sp-12
The following interrelationships will be found particularly useful in predicting the effect upon opacity of a change in either the basis weight or the reflectivity of a sheet of paper. They can also be used to evaluate relative contributions of different pulps, fillers and pigments to optical properties. extensions of these procedures that are cited in the references can be used to evaluate multilayer structures such as coated paper or coated board.