The corrugated industry has moved toward higher usage levels of recycled liner and denser liners to meet customer requirements and to help the environment. These changes require plants to control their normal operating practices on the Corrugator as well as in the Converting department to avoid score cracking problems. A liner’s tendency to crack and/or check will increase with any operational factors that can make the sheet less elastic. Temperature is one such factor. With everything else being equal, colder temperatures will reduce paper elasticity, making the sheet more brittle and thus more likely to succumb to cracking and/or checking during finishing operations. Similarly, linerboard moisture content has a profound effect. With everything else being equal, a sheet of paper acclimated to arid ambient conditions will be more likely to crack and/or check than the same sheet of paper acclimated in a moisture-rich environment. With new Converting equipment often having drying capabilities, it is also possible to overheat the board in the Converting department. The cracking problems occur most frequently at the score lines. Cracking is especially evident during the drier winter months, or in heated storage environments. Today, many corrugated operations are modifying their machines to run hotter and faster, thus further increasing the opportunity for incidents of score cracking. The retention of moisture in combined board is very important to successfully score corrugated board. Most plants are now checking their combined board’s total moisture content, measuring it off of the dry end of the corrugator with an automatic weighing and drying oven (see Special Note). Experience has demonstrated that a target moisture from 5.8 to 7.5% total combined board moisture is typical and can work well throughout the year. Corrugator operating techniques need to be under control if liners are to be run without quality problems. Adding moisture after combined board components have been overheated may not prevent cracking but may lead to other issues like post corrugator warp. Maintenance of the press, especially regarding Total Indicated Run out (TIR) and axial head movement in any area that applies pressure to the combined board, is critical for preventing score cracking. This Technical Information Paper (TIP) includes recommended operating procedures to minimize incidents of score cracking.