The invention relates to a method for manufacturing a biodegradable composition containing nano-particles of cellulose for forming a protective coating on natural materials. It is an object of the invention to provide a composition for forming a protective coating layer on a biodegradable natural material that imparts to the material improved waterproofing and grease-resistant properties. It is another object to provide a composition for forming a protective coating on natural biodegradable materials that is based on the use of nano-cellulose particles and that protects these materials from swelling, warping, and mechanical damage during contact with water, other aqueous liquids, or grease.