A PILOT PAPER-MACHINE EVALUATION OF THE EFFECTS OF PRESSING ON NEWSPRINT QUALITY

The effect of forming and pressing was investigated on a pilot paper m achine equipped with two different wet ends and a press section with f our hips. The design of the former has the greatest effect on sheet st ructure, strength, surface properties, and print density index. Increa sing the loading of either the first or fourth press to a critical val ue increases the strength of newsprint. Strength will decrease if the loading is increased beyond this critical value. The print density ind ex of the sheet is directly related to the consolidation of the sheet in the press section and the calender.