Abstract: A method for providing in a web of sheet material, particularly a paper web, a predetermined moisture content which is uniform throughout the web. The web which has been dried so as to be within the hygroscopic range is directed through an enclosure which is closed off from the outer atmosphere while lapping in the enclosure a perfusion roll having a foraminous wall through which a treating gas, such as air of a given humidity or steam with predetermined properties, can pass into the interior of the roll after first passing through the web which laps the roll. By way of a suitable gas-circulating structure, the treating gas is circulated so as to travel out of the interior of the perfusion roll along a given path back to the web at the exterior of the perfusion roll to pass again through the web and into the perfusion roll, this gas-circulating structure providing the treating gas with predetermined properties for achieving in the web a desired moisture content which is uniform throughout the web.

Abstract: A method and apparatus for providing in a web of sheet material, particularly a paper web, a predetermined moisture content which is uniform throughout the web. The web which has been dried so as to be within the hygroscopic range is directed through an enclosure which is closed off from the outer atmosphere while lapping in the enclosure a perfusion roll having a foraminous wall through which a treating gas, such as air of a given humidity or steam with predetermind properties, can pass into the interior of the roll after first passing through the web which laps the roll.