Cotton pulp is made from rags or clippings from textile mills, raw cotton, and cotton linters. Cotton papers are used primarily as writing papers. Uncoat-ed cover papers generally match the color and finish of corresponding text papers. Physical stresses or changes in humidity cause most curling. This may occur at the paper mill, in the pressroom, on press, or after binding.
Paper tends to curl along, rather than across, the grain of the paper.
Recycled and recycled content papers have less tendency to curl than virgin fiber papers because their fibers are shorter. Wire-covered cylinders are rotated through a vat of pulp, and paper is formed as the water drains from the cylinder. Cylinder machines are used primarily to manufacture paperboard.