This invention is directed to methods for the treatment of cellulose-containing fibers and yarn to provide protection to the cellulose from attack by enzymes. The method comprises the steps of exposing cellulose-containing fibers and yarn to an aqueous solution of an enzyme-repelling chemical to give the fibers or yarn a protective coating, and using the protectively coated fibers and yarn to prepare cloth or fabric. In another embodiment, the method of the invention comprises the step of exposing a fabric comprising cellulose-containing yarn to an aqueous solution of an enzyme-repelling chemical to give the fabric a protective coating. The invention also encompasses cellulose-containing fibers and yarn, including cotton, having a protective enzyme-repelling coating. The invention is further directed to denim fabric comprising cotton fill yarn having a protective enzyme-repelling coating. Such denim fabric, and any garments made therefrom, will exhibit greater strength and durability following the stonewashing procedure as compared to denim made from uncoated yarn.