How do paper
The first mentions of the invention of material for writing texts are found in ancient Chinese sources. The official date of the first appearance of the first paper sheet is considered to be 105 BC, and this event is associated with the name of a dignitary from China, Cai Lun.
The similarity of paper was used before the novelty, but they made this material from strongly steamed silk or hemp. Cai Lun made several experiments, making a unique recipe. In one container were mixed pieces of cloth, ash, mulberry fibers and hemp. All the ingredients had to be mixed thoroughly and evenly put in special forms. Then the billet was dried in the sun and pressed with stones. The result was thin sheets.
It is worth noting that the exact date of the invention of the paper is unknown. Archaeologists have found pieces of paper-like material during excavations in Egypt. And the date of the finds dates back to the 300th year BC.
At the moment, the paper is made in factories equipped with special equipment.There are three production options - from wood or chemical pulp, as well as from waste paper.
Wood pulp is obtained from birch bark, eucalyptus, poplar, pine or spruce. The material is thoroughly crushed using special equipment, and then mixed with a certain amount of water. Next, the mixture falls on the machines that make thin sheets of paper by pressing and leveling. Material of this quality is mainly used for printing newspapers or print publications of relatively low cost. The paper has a yellowish tint and differs not too high strength.
Chemical pulp is used to make higher quality white paper. The process of manufacturing such a material also occurs in several stages. The bark of the trees is crushed into fine chips, which are carefully sifted. Then sawdust for a certain time is boiled in huge boilers. Only after that the resulting mass is mixed with a special acid. For more dense paper, shredded waste paper is often mixed into the bulk.The final stage depends on the requirements. For example, if you need glossy paper, then add resin to the mixture. If you need paper with increased strength, then glue becomes an additional ingredient. After the necessary additives, the mixture is sent under a press and dried thoroughly.
From waste paper to do much easier. "Old" paper is cleaned of paint, which is used for the application of images and text. Then the material is thoroughly crushed and subjected to special processing, thereby forming a mixture resembling semolina. The mass is sent to the rotating belts and is pressed, the bark is sometimes added to the composition. As a result of this process, white paper is produced, which is then cut into sheets and formed into separate blocks.
For the manufacture of colored paper in the standard mixtures are added dyes of a certain color. Sheets that should become velvet, shiny or embossed are subjected to additional processing.