A defect in paper roll winding that results in a roll with an end forming a star-shaped pattern due to buckling of loosely-wound inner paper layers under pressure of more tightly-wound outer layers. Starred rolls (and other roll defects) are the result of inconsistencies in moisture content and thickness produced during the papermaking process. Thicker portions of the paper web will wind more tightly than thinner portions, and the differential tension will result in the variations of the roll that cause starring. Advanced cross-machine direction monitoring procedures in the forming section of the papermaking machine can ensure that the papermaking furnish delivered across the forming wire is consistent in thickness and moisture content, so as not to present problems when building the final paper roll. Variations in the forming of the paper web can also be rectified in subsequent stages of the papermaking process, such as calendering.
Defects in the paper roll have serious consequences for printers utilizing web presses. Rolls that do not unwind into the machine with uniform tension across the web stretch and deform, often beyond their ability to return to their original dimensions, causing various printing distortions. Problems with paper rolls can also cause web breaks. (See also Telescoped Roll.)