Patent ID: 7407562

Claim:
A method for controlling the moisture gradient in production of an uncoated paper web of at least SC quality, having a cross direction, a running direction and a thickness direction, comprising the steps of: pre-moisturizing, with a pre-moisturizer, the paper web in the cross direction substantially across the entire width of the web from an initial moisture content before pre-moisturizing to a selected pre-moisture content; passing the pre-moisturized paper web through a multi-nip calender having at least a first roll stack and a last roll stack, each roll stack having at least three rolls, and wherein the multi-nip calender is situated before a slitter-winder of the web; intermediate-moisturizing the web, with an intermediate-moisturizer, in the cross direction substantially across the entire width of the web before the last roll stack and after a first calendering nip of the first roll stack to a selected intermediate moisture content; drying the web in the last roll stack to a selected final moisture value; continuously controlling the moisture gradient of the web in the thickness-direction in the multi-nip calender by adjusting the pre-moisturizing of the web, based on a calculated or measured value of the selected final moisture value of the web.