BS 1137:1949

This British Standard refers only to Types I, II and III thermo-setting synthetic-resin bonded-paper sheets as defined below. The limits given in the present standard cover Types I and III sheets only, except for flatness and tolerance on thickness which apply to type II sheets also; further investigation is required before limits for other properties can be set for Type II material.

The range of thicknesses of each type is from 1/64 in. up to and including 1 in.