Abstract: A drier, comprising an enclosed casing, means for feeding a sheet of parallel yarns to be dried through the casing in at least one substantially horizontal pass, nozzle boxes disposed above and below the sheet material in each pass to form a drying chamber, means for introducing hot air into the nozzle boxes, and slots in the walls of the nozzle boxes which face the sheet, said slots constituting nozzles effective to discharge hot air from each nozzle box onto the opposed surfaces of the sheet at an angle to the vertical in the range of 30.degree. to 60.degree. and the slots in the upper and lower boxes being slanted in opposite directions to the direction transverse to the direction of travel of the sheet.