Ink and ink balance in offset printing 13 points

Offset printing is the use of the principle of oil-water immiscibility, so that ink and water on the printing plate to maintain mutual balance, in order to achieve network transfer. However, in the actual printing process, the ink is from unstable to relative balance, and then from the new imbalance to the new relative balance. This relatively balanced process is a relatively complex and difficult-to-master work. Only by summing up experience in long-term production practices can we master its regularity.

1. The printing plate must have a solid graphic foundation and blank basis to keep its oleophilicity and hydrophilicity relatively stable. At the same time, the graphic and blank foundations have a good adsorption capacity for printing plates.

2. The grain of the surface of the printing plate must be kept uniform and dense, and have a certain degree of mechanical strength.

3. In principle, the shop is required to be constant humidity and constant temperature, because the temperature change will cause the ink viscosity, fluidity changes, and therefore, the ink loses its balance, especially for the resin ink. Under normal circumstances, it is best to install air conditioners in the workshop and control the temperature within the range of 20~25°C.

4. It is advisable to keep the normal operation and constant speed of the machine in operation during production. The machine is suddenly fast and slow, and it is easy to lose control of the ink and ink balance.

5. The performance of printing ink and paper varies greatly. Different papers and inks are used, and there are different requirements for mastering the ink and ink balance. For example, the paper has the characteristics of tight texture, looseness, and water content. The ink has viscosity, fluidity, and size of pigment particles. Under the condition of the same conditions such as printing plate and temperature and humidity, it is the guarantee of the change of their nature. The premise of balance.

6. The addition of dry oil in the ink promotes the drying of the ink, but it also promotes the increase of ink viscosity. Therefore, the improper use of dry oil is the main factor that causes the ink balance to lose control and dirty.

7. The pH of the fountain solution is also the main condition affecting the ink-water balance and must be kept constant.

8. The printing press must have precise roller pressure, ink roller pressure and water roller pressure. These three pressures directly determine the balance of ink and water.

9. In the case of printed text or text lines, under the premise of ensuring the clearness of outlets, the amount of ink may be increased.

10. Some inks have poor coloring power and the printed products are dull and lifeless. In this case, the amount of ink can be increased appropriately.

11. One-sided printing can be thicker than double-sided printing.

12. Coated paper and glass paper jams have smooth surfaces and low absorption, so they should use less ink, especially when printing real maps. The amount of ink should not be too large.

13. For thinner paper, the ink layer is not directly printed thick when printing, but the rough, absorbent paper, the amount of ink can be enlarged.

Source: Bison