Several factors that should be considered when adjusting the concentration of fountain solution in offset printing

The fountain solution has a great influence on the stability of the print quality of offset printing products. In order to make the printed images well-colored and clear ink, and the blank layout can not be dirty, it is necessary to rationally adjust the concentration of fountain solution according to the specific printing conditions to ensure the printing of high-quality prints.

1, paper performance and fountain solution concentration

When the texture of the printing paper is loose or dust is contained in the paper, due to the great viscosity of the printing ink, the paper wool and the paper powder are often accumulated on the blanket, which will inevitably increase the friction of the printing film layer and make the printing plate easy. Dirty, in this case, should be appropriate to increase the concentration of fountain solution; and print tough and white paper texture, especially when printing coated paper and glass cardboard, should be appropriate to reduce the concentration of fountain solution.

2, ink performance and fountain solution concentration

Due to the different properties of printing inks, the properties such as viscosity, flowability, and acid resistance are also different. The reaction to the concentration of the fountain solution will also be different. Therefore, the concentration of the fountain solution should be adjusted as appropriate. In general, the principle of using the concentration of the fountain solution is: the concentration of the printed red ink is greater than the concentration of the printed black ink; the concentration when printing the black ink is greater than the concentration of the printed blue ink; and the concentration when printing the dark ink is greater than The density of printed light ink.

3, the amount of desiccant

When printing multi-color plate products, in order to speed up the drying of the ink, dry ink should be added to the ink. This also increases the viscosity of the ink particles and increases the viscosity of the blank area of ​​the printing plate. Edition ills. Based on this situation, the amount of raw liquid should be appropriately increased.

4, printing plate and fountain solution concentration

The layout of printed products is varied, with both on-site layouts and lines and textured layouts. If the layout is dominated by lines and solid vignettes, the density of the fountain solution should be adjusted to a larger extent due to its small area of ​​cloth, so that the blank layout is not easy to get dirty: if the entire plate is a dot structure, it should be The use of a low concentration of fountain solution; and for the printing of the printing plate in the field and the dot, we should take the principle of taking into account all aspects to ensure the quality of the printed product.

5, workshop temperature and fountain solution concentration

When the temperature of the printing environment increases, the molecular motion of the material will inevitably accelerate, the fluidity of the ink will increase, and more free fatty acids will be decomposed at the same time. This will make the printing plate easier to produce dirt. Therefore, when the temperature is high, the dampening fluid should be properly increased. concentration.

6, printing speed and fountain solution concentration

Due to the thixotropic characteristics of the ink, when the printing speed is high, the ink roller of the printing machine has a large coefficient of friction, which tends to cause the ink to become thin due to heat generation. This causes the tinting strength of the ink to decrease and the ink color to fade. In this case, the amount of ink required to be increased can be increased. Printing ink, this printing plate is prone to dirty. Therefore, when the printing speed is high, the concentration of the fountain solution should be appropriately increased.

In addition to the above, if the printing pressure is large, and the blanket and liner texture is too stiff, it should be considered to appropriately increase the concentration of fountain solution in order to achieve a better anti-dirty effect. The above situation shows that the concentration of fountain solution should be comprehensively considered according to various specific conditions.

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