nge from about 80:20 to about 20:80, and wherein the cellulose derivative is selected from he group consisting of hydroxyethylcellulose, hydroxpropylcellulose, carboxymethylcellulose and mixtures thereof; or (3) a biopolymer produced by the action of bacteria, fungi, or other microorganisms on a suitable substrate; or (4) mixtures of a bentonitic clay and an additive comprising (a) a nonionic, wat