Aqualon ethylcellulose (EC) is a cellulose ether made by the reaction of ethyl chloride with alkali cellulose. During the reaction, the substitution of ethoxyl groups is controlled to a commercially useful range of 48% to 52% ethoxyl (or 2.3 to 2.6 ethoxyl groups of a theoretical maximum of 3.0) per anhydroglucose unit. Over this ethoxyl range, Aqualon ethylcellulose is classified into three ethoxyl types (N (Low substitution) ,T (Mid substitution), X (High substitution)) and into a range of polymer viscosities for ease of use.