... ,final setting 15 gypsum powder for cement/chalk:we are the professional manufacture for gypsum powder. we have ourselves ... 120 mesh,Initial setting 7 minutes, Final setting for 15 minutes.C) Whiteness is 75% above,the ... hourse),fineness of 250mesh,Initial setting 7 minutes, Final setting for 15 minutes. Useful: cornice, chalk, ceiling, contruction, ... advance after 15 days. Gypsum Powder for cement/chalk