Fountain solution adjustment and other factors

Fountain solution has a great influence on the stability of offset printing quality. In order to make the printing ink bright and clear, and the blank page not dirty, it is necessary to reasonably allocate the concentration of the fountain solution according to the specific printing conditions, so as to ensure the printing quality. Today, the editor of China paper network takes you to know more about the relevant content.

Paper properties and fountain solution concentration

When the texture of the printing paper is loose or there is dust in the paper, due to the high viscosity of the printing ink, the paper wool and paper powder will often accumulate on the blanket during the embossing, which is bound to increase the friction of the plate film and make the plate easy to get dirty. In this case, the concentration of the fountain solution should be appropriately increased; When printing tough and white paper, especially when printing coated paper and glass cardboard, the concentration of fountain solution should be appropriately reduced.

Ink: performance and fountain solution concentration

Due to the different properties of printing ink, its viscosity, fluidity and acid resistance are also different, and the reaction to the concentration of fountain solution is also different. Therefore, the concentration of fountain solution should be adjusted as appropriate. Generally speaking, the size of the fountain solution concentration principle is: when printing magenta ink, the concentration is greater than that of printing black ink; The concentration of black ink is higher than that of green ink; The concentration of dark ink is higher than that of light ink.

Dosage of desiccant

When printing stacked color plate products, in order to speed up the drying speed of the ink, the ink should be added with drying oil, which also makes the ink particles coarsen and viscosity increase, so that the fat sensitivity of the blank part of the printing plate increases, which is easy to cause the problem of paste. Based on this situation, the amount of stock solution should be increased appropriately.

Plate and fountain solution concentration

The layout structure of printed products is various, including field layout, line layout and mesh layout. If the layout is dominated by lines and field Yin characters, due to its small ink area, the concentration of fountain solution should be appropriately adjusted larger, so that the blank layout is not easy to get dirty: if the whole plate is dot structure, low concentration of fountain solution should be used; For the printing site and dot coexisting plate, we should take into account the principle of many aspects to ensure the stability of print quality.

Workshop temperature and fountain solution concentration

When the printing environment temperature rises, the molecular motion of the material will accelerate, the ink fluidity will increase, and more free fatty acids can be decomposed, which makes the printing plate easy to produce dirty phenomenon. Therefore, when the temperature is high, the concentration of the fountain solution should be appropriately increased.

Printing speed and fountain solution concentration

Due to the thixotropy of the ink, when the printing speed is high, the friction coefficient of the ink roller of the printing machine is large, and it is easy to generate heat, so that the ink becomes thinner, the coloring force is reduced, and the ink color is light. At this time, the ink feeding amount needs to be increased to deepen the printing ink color, so that the printing plate is prone to dirty. Therefore, when the printing speed is high, the concentration of fountain solution should be increased appropriately.

In addition to the above, if the printing pressure, blanket and liner texture is too hard, should also consider increasing the concentration of fountain solution, in order to achieve better anti dirty effect. The above situation shows that the concentration of fountain solution should be considered comprehensively according to various specific conditions.