Paper360 - January/February 2012 - (Page 18)

PAPER CURL MILL WISE The Problem of PAPER CURL Making a quality sheet of paper is hard enough, and paper curl doesn’t make it any easier CHARLES GREEN and JIM ATKINS M aking a quality sheet of paper can be hard enough, but one problem that can make it almost impossible is paper curl. Curl affects almost every grade of paper and board. It causes paper jams in printer/copiers, print register problems in newspaper presses, and combined board warp (curl) issues for corrugators (Figure 1). As a papermaker, curl can be particularly frustrating because a sheet that appears to be flat “as manufactured” may curl quite badly in the customer’s converting operation. Addressing curl problems requires that we look at our process and the very structure of paper to find out why curl is occurring. And it is very often the case that “the lack of information is all-pervasive; every link in the production and logistics chain can make a difference.”1 Each problem is usually a unique combination of paper properties and end-use conditions. Figure 1. Twist warp of corrugated board due to fiber alignment problems. 18 Paper360º JANUARY/FEBRUARY 2012

Table of Contents for the Digital Edition of Paper360 - January/February 2012

Over the Wire . . . News Summary
Thinking Small Is Leading to Big Changes
Who’s in Control in the Packaging Industry?
The Problem of Paper Curl
Preventing Bacterial-Generated Gas Explosions
Environmental Challenges for the Coming Decade
Association News

Paper360 - January/February 2012