Predicting the Fluting Tendency of Light Weight Coated Paper, 1996 International Printing & Graphic Arts Conference Proceedings

Theodore G. Waech and Daniel H. Sze

Beloit Corporation Research

Fluting is MD waviness found after lightweight coated papers are printed by the web heatset offset process. The paper develops rucks due to the unsupported hot, moist web under tension in the dryer, and the dried ink appears to cement in rucks of about one centimeter wavelength. To investigate, printing trials were run on a four color web heatset offset press. Papers from several commercial sources were tested as well as rolls of commercial raw stocks that had been coated and/or calendered on pilot machinery. The prints were evaluated for fluting (waviness) both visually and by using a laser profilometer. Fluting correlated very closely with simple laboratory tests for ink absorption -- the K & N test and Leneta ink test. Coatings of clay only usually absorbed little and fluted little, and of the coatings tried, those high in calcium carbonate absorbed much and fluted much. Coating formulation largely determines the potential for fluting.