... 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 tensile strength, early intensity, non-shrinkage, non-delaminating, clear and fine surface, simple operation, ...