In fact, before paper was invented, "brown paper" was actually made from calfskin. At present, this "brown paper" is only used to make drums. Current kraft paper is chemically made from the wood fibers of conifers, then put into a beater for beating, adding glue and dye, and finally paper in a paper machine. We used to call it vellum because it was yellowish-brown in color, and because it was so tough that it resembled cowhide.
The production method of kraft paper is no different from that of ordinary paper, but the wood fiber used for making kraft paper is longer, and when cooking wood, the wood is treated with caustic soda or alkali sulfide and other chemical substances. The chemical action is mild and the damage to the original strength of wood fiber is small. This pulp paper is tightly bound to the fibers and is not easily broken, so craft paper is stronger than ordinary paper. Because craft paper is strong and does not absorb water easily, it is often used as packing paper.
In the production process, there is not much difference between kraft paper and ordinary paper. Most importantly, it uses conifer wood as its raw material. Its fibers are longer than other plant fibers, and the molecules bind more tightly to each other.
In order to maintain the strength of kraft paper during production, strong handling conditions should be avoided during pulping and bleaching to avoid damaging the fibers. As a result, we see brown paper, not white. In addition, the craft paper in the production process will also add glue to increase the strength. All this makes craft paper stronger than ordinary paper.
