... special grade gypsum powder, Methyl Cellulose (HPMC), retarder 2) Joint comp Features: 1) Materials: special grade gypsum powder, Methyl ... Cellulose (HPMC), retarder 2) Joint compound powder provides the performances of strong binding force, high ... mixture. It also sticks both ends of cornice c) Concreting after 1 hour Packing: 20kg/bag Joint Compound Powder