to form the cellulose ether derivative alternatively the decolorized rcl may be treated simultaneously with an etherifying agent and a base to form the cellulose ether derivative the bases used in the preparation of the cellulose ether derivative are those that are known in the art and may be selected from the group consisting of sodium hydroxide potassium hydroxide calcium hydroxide barium hydroxide ammonium hydroxide lithium hydroxide strong organic bases and mixtures thereof the strong organic bases for use in the preparation of the cellulose ether derivative may be selected from the group consisting of amines quaternary ammonium hydroxides and mixtures thereof a preferred base for use in the preparation of cellulose ether derivatives is sodium hydroxide the etherifying agent used in the preparation of the cellulose ether derivative are those that are known in the art and may be selected from the group consisting of alkyl halides alkenyl halides alkylene oxides alkyl glycidyl ethers aryl glycidyl ethers alk aryl glycidyl ethers metal salts of alpha halogenoalkanoates vinyl sulfonates and mixtures thereof it is also possible to select the etherifying agent from the group consisting of methyl chloride ethyl chloride ethylene oxide propylene oxide monochloroacetic acid and salts thereof butyl glycidyl ether and glycidyl silane in particular the etherifying agent may be 3 glycidoxypropyl trimethoxysilane 3 glycidoxypropyl methyldiethoxysilane or 3 glycidoxypropyl dimethoxysilane the carboxymethylated derivatives made from decolorized rcl are water soluble or water swellable and exhibit enhanced solution viscosity they provide improved performance properties higher saturated salt water and fresh water fann viscosity in water based drilling muds as compared to.