HPMC is made by propylene oxide, methyl choride with alkali-cellulose  after a chemical process called etherification under rigidly controlled conditions.  The resultant nonionic polymer is purified , dried and ground  to a fine white powder, this water-insoluble cellulolse is turned into water-soluble nonionic polymer. HPMC is a good film-former and varies somewhat in physical and chemical properties. HPMC is quite hydrophilic and readily soluble in cold water.