HEAVY PAPERS AND CURL MEASUREMENT

Characterization of paper curl is often complicated by the bending cau sed by the paper's own weight. We analyze this effect theoretically an d show that the out-of-plane deviation of sheet edges under gravity is simply related to the curl and bending stiffness of paper or board. T he analysis is verified with experiments on stacks of thin printing pa pers. It is found that oven-dried stacks can be used as a quick measur e of the curl of wood-containing papers with the exception of SC grade s. The paper's own weight appears to stabilize the shape of the sheet. It might be possible to use a similar set-up to measure wood-free pap ers.