Colatting

Colatting is a process used in the production of paper, particularly in the production of newsprint. It involves the use of a chemical called sodium dithionite to reduce the lignin content in wood pulp, making it more suitable for printing. The process was developed in the late 19th century and has since become an integral part of the paper-making industry.

The term "colatting" is derived from the French word "colater," which means to bleach. The process involves the addition of sodium dithionite to the wood pulp, which reacts with the lignin to form a water-soluble compound. This compound is then removed from the pulp, leaving behind a more pure cellulose fiber that is suitable for printing.

Colatting is an important step in the production of newsprint, as it allows for the production of a high-quality, low-cost paper that is suitable for printing newspapers and magazines. The process is also used in the production of other types of paper, such as tissue paper and packaging materials.

The use of sodium dithionite in the colatting process has been the subject of controversy, as it is a hazardous chemical that can pose a risk to workers and the environment. In recent years, there has been a push to develop more environmentally friendly alternatives to the colatting process, such as the use of oxygen delignification. However, colatting remains an important and widely used process in the paper-making industry.