two square pieces of paper with the same size, and the creases of straight and vertical wires are compared. It is easier to fold along the silk and the crease is straighter; Vertical wires are not easy to fold, and the creases are irregular.

the thread direction of paper is also called the direction of paper or the grain direction of paper. In the process of papermaking, when the pulp flows from the headbox to the screen, due to the interaction of the kinetic energy of the pulp water flow and the high-speed screen, the fibers of the paper are arranged roughly regularly according to the running direction of the paper machine, thus forming the filament direction of the paper.

In manual papermaking, most of the water in the pulp is leaked through a screen by manual shaking, and at the same time, the paper fibers can be evenly distributed within the screen.