Many remember making paper in elementary school from vegetable scrap and newsprint. Contrary to popular perception, however, this high-output industry employs a wide range of advanced technologies from computer software to chemical engineering. Mechanical-pulp paper, such as newsprint, is made by separating wood fibres by mechanical means to produce pulp.
Mechanical processes produce a much higher yield of pulp than chemical processes.
The reason for this is that chemical processes dissolve all the lignin, the substance that binds the wood fibres together. In contrast, mechanical processes simply degrade the lignin, so that the wood fibres fall apart. While this leads to a greater yield of pulp, the paper produced tends not to last as long, since lignin turns paper yellow when it ages. Process control involves fine-tuning each stage of the paper making process in order to improve the consistency and quality of the final product. Researchers at the Mechanical Wood-Pulps Network are developing software and equipment to enhance process control in paper mills.