there is disclosed a method for the ammonia saturation of wood to impart flexibility thereto which includes the step of sealing the surfaces of ammonia - saturated wood with a polymeric film which has limited or no permeability to either or both ammonia and water vapor . preferably , the polymeric film is flexible so the working of the wood product by bending , twisting , embossing , molding , etc . will not destroy the film . the polymeric film should also be soluble in a selected solvent , thereby permitting its removal after the wood has been formed in a final , desired shape to permit water vapor to re - establish crosslinking of the cellulose chains and restore its natural , rigid condition .