In the printing process, due to the influence of downtime, the change of temperature and humidity in the printing workshop, the running speed of the printing machine, the types of ink and paper, and the weakening of hydrophilic performance of the blank part of the page with the increase of printing copies, even if the water delivery device is adjusted and operated correctly, it will directly affect the ink balance.
The printing plate must have a solid graphic foundation and blank foundation, and keep the oleophilic and hydrophilic performance relatively stable. If a certain condition is not met, ink and wash will lose balance.
The thickness of the sand net should be well controlled. The sand net on the surface of the printing plate must be uniform and fine, with certain physical strength, so that the graphic and blank parts have a solid attachment foundation and good water storage conditions.
The temperature and humidity in the workshop should be constant. In principle, the workshop is required to maintain constant temperature and humidity, because the change of temperature will cause the change of ink viscosity and fluidity, and the increase of temperature will make the water evaporate, thus making the ink out of balance. Especially resin ink, is very sensitive to temperature. It is best to install air conditioner, and the temperature should be controlled within the range of 20℃ ~ 25℃.
The machine should run at a constant speed. In production, the machine must run at normal speed and uniform speed, and the machine is fast and slow, which is easy to make the ink balance out of control.
Master the characteristics of different types of paper, ink and other raw materials. The properties of ink and paper are very different. Using different paper and ink has different requirements for ink balance. For example, paper can be divided into tight and loose texture and water content; Ink has viscosity, fluidity, pigment particle size and so on. Under the same conditions of printing plate, temperature and humidity, we must master the changes of their performance.
The amount of drying oil should be moderate. Drying oil in ink can accelerate ink drying, but drying oil will make ink sticky. Therefore, the improper amount of dry oil is the main factor that causes the ink balance to be out of control and dirty.
The pH value of wetting diluent should not fluctuate. The pH value of fountain solution is also an important condition affecting the balance of ink and wash. It must remain unchanged to avoid large-scale fluctuations.
Adjust the pressure correctly. The printing press must have accurate cylinder pressure, ink roller pressure and water roller pressure, which directly determine the balance of ink.