Abstract: In a method and apparatus for sizing a yarn sheet, the yarn sheet is passed over rollers through a wetting unit and a following roller nip that reduces the moisture content to a selected level. The wetted yarn sheet then passes through a sizing unit and over rollers forming a nip to reduce the sizing content to a desired level. The rollers of the wetting unit and the rollers of the sizing unit are in close proximity to minimize the reach of the yarn sheet there between and thereby minimize the heat loss in the yarn sheet. The reach is covered by a cover having a heater that extends over the yarn sheet reach to maintain the yarn sheet at a desired temperature as it enters the sizing unit. The temperature of the wetting agent bath in the wetting unit is 65°-95° C., with the temperature of the wetting agent being approximately 5°-10° C. higher than the temperature of the sizing agent bath.