Printing is divided into printing production procedures, direct printing and indirect printing.
Indirect printing means that the printing ink on the layout needs to be transferred to the cylinder first, and then the ink is transferred to the printing material by the cylinder. Such as the popularly known as rubber printing machine is one of them. For the direct printing plate, the printing pattern is the reverse image, and for the indirect printing plate, the printing pattern is the positive image.
According to the principle that printed products are produced during the printing process between the printed part and the non-printed part on the printing plate, it can be divided into two types: physical printing (PhysicalPrinting) and chemical printing (ChmiacalPrinting).
In physical printing, the printing ink is a kind of accumulation and bearing in the printing part, and the part without printing is concave or convex, which is different in height from the printing part and cannot be stained with the printing ink, leaving it blank. Therefore, the transfer of the printing ink from the printed part to the material to be printed is a physical and mechanical action. General gravure printing, letterpress printing, stencil printing, offset printing, etc. All are physical printing (the printing surface is higher or lower than the non-printing surface).
Chemical printing refers to the non-printed part of the printing plate (non-printing surface) that does not stick to the printing ink. It is not because the part is low concave or convex or blocked, but because of the chemical effect, it produces a water-absorbing and ink-repellent film. The printed part (printing surface) absorbs ink and repels water, and the non-printed part absorbs water and repels ink. It is still a physical phenomenon that water and grease repel each other. However, during the printing process, the non-printed part should be added to the water tank solution to absorb water and repel. The ink film must be added with acids and glues to supply the mucous acid layer of the carboxy gene so as to keep the non-printing surface of the printing plate from being invaded by grease, so it is chemical printing.
