Cardboard is a popular name for any stiff paper or paperboard that is more than 0.012 inch (0.3048 millimeter) thick. It usually does not mean paper used for special purposes, such as wallboard or corrugated boxboard. Papermakers use various names for different kinds of cardboard. The name may be based on the raw material used, such as newsboard, a coarse cardboard made from newspaper pulp. It may indicate useful characteristics, such as bending board. Or it may designate the final use, such as poster board or shoe board. A familiar type of cardboard, called bristol board, is used for such products as index cards and postal cards. Manufacturers make cardboard by pasting several layers of paper together or by pressing layers of wet pulp together. They often coat cardboard for decoration or to improve the surface of the cardboard for printing.
