mechanical wood pulp
n.A paper pulp made by physically grinding wood without separating the cellulose fibers from impurities such as lignin.
NotesPaper made from mechanical wood pulp has relatively low strength, discolors fairly rapidly upon exposure to air and light, and has very little permanence. It does, however, possess good bulk, opacity, and compressibility. Life expectancy is relatively low for wood pulp paper - about 100 years - depending upon storage, handling, acidity of inks or pigments used upon the paper, and sizing.