Calcium Carbonate CaCO3, a naturally occurring substance found in a variety of sources, including chalk, limestone, marble, oyster shells, and scale from boiled hard water. It is a key ingredient in today's paper coatings. The calender smoothes the paper by compression.
Caliper is a critical measure of uniformity.
Excessive variation in caliper can lead to print variation, undesirable visual effects, and uneven stretch or press-feeding problems. It can also create problems in folding and binding. To manufacture cast-coated paper, a paper web with wet or moistened coating is brought into contact with a polished chrome drum surface. This surface is replicated on the coated sheet. In general, cast-coated papers combine a superior flat surface with excellent ink receptivity, making them the best of printing surfaces for all printing processes.