Paper mill. A container of wood chips outside a paper mill. Paper is made from vegetable fibre, mainly from wood pulp. Soft woods such as spruce and fir, as well as poplar, are debarked, ground and pressed into sheets. The pulp is then chemically treated to improve resistance to tearing, bleached, and passed through heavy rollers to give a smooth finish. The paper may be coated with clay or other mineral pigments if a better surface is required.