How is wood turned into papermaking pulp?
There are two main processes, depending on the end use of the pulp. To make mechanical pulp, the wood is first chipped (a wood chip is typically about 50mm x 30mm x 5mm in size) and then the chips are fed to a refiner which disintegrates the chips into individual fibres, by forcing them between two large ribbed disks which counter-rotate at high speed, very close together. Often the chips are first softened by heating, or soaking in caustic soda or other chemicals. Mechanical pulp is typically used in newsprint, magazine paper and paper towels. In mechanical pulping, the lignin remains with the fibres.
