(1) On-line polishing
On-line polishing directly connects the polishing unit to the printing unit, that is, printing and polishing are carried out on the same machine, which has the advantages of high speed, high production efficiency, low processing cost, reduced the handling of printed matter, overcome various quality failures caused by powder spraying, and is the future development direction. But on-line polishing requires high polishing technology, polishing oil, drying equipment and polishing equipment.
(2) Offline polishing
Off-line polishing uses a special polishing machine to polish the printed matter, that is, printing and polishing are carried out on their own special equipment. The polishing method is flexible and convenient, and the investment of polishing equipment is small. It is more suitable for professional post-press processing manufacturers. However, this way of polishing increases the transfer work between printing and polishing processes, resulting in low production efficiency.
According to the types of polishing products, it can be divided into: full-width polishing, partial polishing, extinction polishing and artistic polishing.
(1) Full-width illumination
The main function of full surface gloss is to protect the printed matter and improve the surface gloss of the printed matter. In general, roll coating is used to gloss the whole surface.
(2) Local polishing
Local polishing is generally used to polish the image and text parts that need to be emphasized in the printed matter. The high gloss picture of the polishing part is compared with the low gloss picture of the non-polishing part, which produces wonderful artistic effect. Local polishing is carried out by printing, in which the film layer obtained by screen printing is thicker, the effect is more obvious than other methods, and the cost is lower. At present, it is widely used in China, but its production efficiency is generally lower.
(3) Extinction and polishing
Ultraviolet matte polishing oil is used for extinction polishing. Contrary to ordinary polishing, it reduces the gloss of the printed surface and thus produces a special effect. Extinction polishing is a popular way of polishing at present because of the stimulation of excessive gloss to human eyes to a certain extent.