Method for casting clay coating

Claim 1

IN THE MANUFACTURE OF PAPER AND PAPERBOARD SHEETS HAVING A CAST MINERAL LAYER BONDED TO ONE SURFACE THEREOF, WHEREIN A THIN LAYER OF AQUEOUS MINERAL COATING COMPOSITION IS FIRST APPLIED TO A HEATED CASTING SURFACE AND DRIED IN CONTACT THEREWITH, AND WHEREIN A PAPER OR PAPERBOARD WEB THE CONTACTING SURFACE OF WHICH IS COATED WITH A CONTINUOUS FILM OF BONDING ADHESIVE IS FED INTO CONTACT WITH THE DRIED MINERAL LAYER AND ADHERED THERETO UNDER PRESSURE, AND THE WEB THEREAFTER UTILIZED TO STRIP THE MINERAL LAYER FROM THE CASTING SURFACE AS A DISCRETE LAYER BONDED TO THE WEB, THE EXPOSED SURFACE OF THE MINERAL LAYER HAVING A CAST FINISH CORRESPONDING TO THE FINISH OF SAID CASTING SURFACE, THE IMPROVED METHOD FOR APPLYING A SLURRY OF AQUEOUS MINERAL COATING COMPOSITION OT THE CASTING SURFACE AND FORMING IT INTO A THIN, UNIFORM LAYER, WHICH METHOD COMPRISES APPLYING A SLURRY OF MINERAL COATING COMPOSITION TO THE CASTING SURFACE TO FORM AN INTIAL LAYER THEREON, AND WHILE THE BODY OF SAID INITIAL LAYER IS STILL FLUID BUT AT A TIME WHEN THE SURFACE THEREOF IN CONTACT WITH THE HEATED CASTING SURFACE HAS BEGUN TO DRY, SUBJECTING THE EXPOSED SURFACE OF THE LAYER TO AN AIR SMOOTHING OPERATION IN WHICH THE EXPOSED SURFACE OF THE LAYER IS SMOOTHED AND REDUCED TO UNIFORM THICKNESS THROUGHOUT, SAID AIR SMOOTHING OPERATION BEING PERFORMED AT AN AIR PRESSURE SUFFICIENT TO DISPLACE AND SMOOTH THE EXPOSED SURFACE OF SAID LAYER BUT OF INSUFFICIENT MAGNITUDE TO DISPLACE THE SURFACE OF THE LAYER IN CONTACT WITH THE CASTING SURFACE, AND IMMEDIATELY FOLLOWING THE AIR SMOOTHING OPERATION SUBJECTING THE EXPOSED SURFACE OF THE SMOOTHED LAYER TO A CURRENT OF HEATED AIR TO EFFECT THE RAPID DRYING OF THE LAYER IN THE SMOOTHED CONDITION.