A cellulase preparation consisting essentially of a homogeneous endoglucanase component which is immunoreactive with an antibody raised against a highly purified .about.43 kD endoglucanase derived from Humicola insolens, DSM 1800, or which is homogeneous to said .about.43 kD endoglucanase, may be employed in the treatment cellulose-containing fabrics for harshness reduction or color clarification or to provide a localized variation in the color of such fabrics, or it may be employed in the treatment of paper pulp.