PRE-CALENDERING - OPERATING EXPERIENCE ON NEWSPRINT

Pre-calendering, with resilient nips in the dryer section, can improve surface smoothness and print quality without blackening, mottle, or o pacity loss, and can be adjusted to correct two-sidedness. The pre-cal endering process treats the sheet at a high moisture content and high temperature, so that less dry end calendering is required to achieve t he final sheet finish. This process can achieve many of the benefits o f soft on-line calenders with simpler technology, and equipment which is much easier to install. Four installations are now running, includi ng one recently started up on a newsprint machine. Operating experienc es an sheet qualities from this commercial unit are discussed in detai l.