Long ago, "kraft paper" was really made of calf skin. The kraft paper used now is made from wood fibers of conifers after people have learned the technology of papermaking. They are pulped by chemical methods, and then put into a beating machine for beating, and then sizing materials, dyes, etc. are added, and finally made into a paper machine. Paper. Because the color of this paper is yellow-brown, the paper is tough and resembles cowhide, so people call it kraft paper.