Goodyear Grade Note Guudpoly GR20L Liquid form, for gypsum board. Guudpoly GR40L Liquid form, for gypsum board. Guudpoly GR41 Powder form, for dry based gypsum plaster and all dry gypsum products pH > 7 Guudpoly GR42 Powder form, for dry based gypsum plaster and all dry gypsum products pH 7. High Concentration Grade. Guudpoly GR91 Powder form, for dry based gypsum plaster and all dry gypsum products. very high concentration grade.