How to deal with the "dry" phenomenon in lithography

The major influencing factors of water-dry failures include printing plates, ink-on-water systems, and fountain solutions.

If the pressure between the ink form roller and the printing plate in the ink supply system is set correctly, water-drying still occurs, which may be caused by improper pressure setting between the water rollers in the water supply system. Especially when using an alcohol fountain solution, since the surface tension of the alcohol fountain solution is low and the spreadability is good, a small amount of dampening solution in the blank portion of the printing plate can form a uniform water film, thereby greatly reducing the Layout water supply. Therefore, the pressure between the water rollers is insufficient and it is more likely to cause the dry plate phenomenon. On the other hand, if there is oil on the water roller, it will also affect the water supply volume of the water roller, which will lead to water and dry failure of the plate layout.

Even if the amount of fountain solution and alcohol used in the printing process is set correctly, it does not mean that the quality of the used fountain solution is stable. The fountain solution should also have buffering properties for pH, plate protection, wettability, corrosion protection, bactericidal properties, and antifoam properties. The buffer in the fountain solution is mainly used to stabilize the pH of the fountain solution because the fountain solution is generally acidic. As the amount of buffer added, the pH of the fountain solution will fluctuate more. Improper amount will affect the hydrophilic properties of the printing plate. The protective performance of the printing plate refers to the protection of the hydrophilic properties of the printing plate. If it is used improperly, it will also reduce the hydrophilic properties of the printing plate and cause water-drying. The bactericide can prevent algae and microorganisms from breeding in the water circulation system and avoid clogging of pipelines. The anti-foaming agent can prevent the formation of bubbles and prevent the large amount of foam in the water tank from being detrimental to the wetting of the printing plate.

Therefore, when water-drying occurs during offset printing, it is necessary to first check whether the pressure setting between the ink roller and the water roller is correct, and at the same time, clean the water roller regularly. In addition, high-quality fountain solution must be selected during the printing process. When selecting the fountain solution, the user should combine the water quality and other conditions of the printing plant to strictly control the amount of fountain solution added, isopropyl alcohol ( The amount of alcohol added, the pH of the fountain solution, and the conductivity.

In summary, it can be seen that the main factors of water-dry failure during the offset printing process are the printing plate, the inking water supply system, and the fountain solution. Even if the amount of alcohol used in the fountain solution and the usage amount of the fountain solution are correct, Also due to other factors caused by offset printing water phenomenon.