A method of method of making a formed ceramic body, comprising casting or jiggering a composition comprising a mullite-rich calcined kaolin obtained from a hydrous kaolin. Also provided is a method of modifying/increasing the casting rate of a formed body formulation comprising hydrous kaolin, the method comprising substituting at least 10% of the hydrous kaolin in the formulation with a mullite-rich calcined kaolin. Also provided is a ceramic body filter cake comprising a mullite-rich calcined kaolin, wherein the mullite-rich calcined kaolin is obtained from a hydrous kaolin and a method of modifying/increasing the filtration rate of a ceramic body filter cake comprising hydrous kaolin, the method comprising substituting at least 10% of the hydrous kaolin in the ceramic body filter cake with a mullite-rich partially calcined kaolin. Also provided are dried greenware products and final ware products comprising a mullite-rich calcined kaolin, wherein the mullite-rich calcined kaolin is obtained from a hydrous kaolin.