The ink-water balance refers to adjusting the supply of fountain solution at a certain printing speed and printing pressure, so that the proportion of the volume of fountain solution contained in the emulsified ink is controlled at 15% to 26%, forming a slightly water-in-oil ( W/O) type emulsified ink, with the smallest amount of liquid to compete with the ink on the plate.
The most important part of the ink balance is the fountain solution and ink control. The fountain solution is composed of water and a surfactant. The fountain solution can fully wet the layout, and has the cleaning ability and pH value to ensure that the layout is not dirty.
1) Effect of fountain solution
1 Form an average water film in the vacant sector of the printing plate to prevent the ink on the graphic from infiltrating into the vacant department and prevent the dirty plate.
2 The electrolyte in the fountain solution reacts chemically with the metal plate substrate exposed due to wear, continuously forms a new hydrophilic layer, and maintains the hydrophilicity of the affixed sector.
3 Control the temperature of the layout ink. Because the speed of the new printing press is getting faster and faster, too fast printing speed will increase the temperature of the ink during high-speed transmission, and the ink activity will increase, resulting in an increase in the number of dots. Therefore, the high-speed machine puts forward a new requirement for the fountain solution, that is, the fountain solution can reduce the temperature of the ink roller and the ink when contacting the ink roller through the layout.
4 Do not enlarge or reduce the graphic. The fountain solution must have the function of not disturbing the relative position of the printing and publishing department and the vacant department, ensuring that the graphic is neither enlarged nor reduced during the entire printing process.
The ink is generally composed of pigments, fillers, binders, and auxiliary additives. The ink's rheological function and optical function should be fully considered when selecting the ink.
The rheological function of the ink is the main basis for determining whether the ink has a good printing function. The rheological function of the ink is mainly determined by the binder of the ink, and of course, it can also be properly adjusted by the auxiliary additives. The evaluation of ink rheological performance can be reflected by the main indicators of ink rheology, namely ink viscosity, viscosity, thixotropy, yield, viscoelasticity, and activity. In actual production, only by grasping these performance indicators can we be familiar with the printing properties of various types of inks, so as to achieve the purpose of selecting inks that meet the printing requirements.
The ink and water on the printing plate must be present at the same time to maintain balance. The purpose is to maintain the maximum ink loading in the graphic printing area, so that the ink is bright, saturated, and the dots are clear and clean, and the printing area must be kept clean and tidy. This requires In production, pay attention to regulating the relationship between water supply and ink supply.
In printing, the darkness of the ink printed on the prints, in addition to the amount of ink on the ink fountain, is directly affected by the amount of water supplied and the ink balance on the layout. When the moisture content of the layout increases, the blotting ink color gradually fades to lighten. On the contrary, reducing the amount of water used to reduce the amount of water on the layout, the ink will be relatively deeper than the original. Therefore, increasing or decreasing ink supply and layout water supply will change the depth of blotting ink. In the printing process, it should be adjusted according to the actual situation. Instead of relying solely on reducing the amount of water supply to improve ink, it is easy to make the vacant department dirty because the water is too small and the ink and water balance is lost.
However, there is a need to prevent flooding. When water is excessive and the ink becomes light, you must not ignore the actual situation, mistakenly assume that the amount of ink is small, and do not reduce the amount of water supply, but frequently increase the amount of ink. So reciprocatingly increasing the supply of ink and water, causing a vicious cycle, the ultimate full of all the ills of the water and large ink, so that printing can not be normal.
Experienced printers, in actual production, often ensure that the printing plate is not dirty, control the water supply to the smallest possible range, and make the amount of water supply and ink supply less inconsistent. State, this will ensure that the printed ink is consistent in depth before and after printing and the print homework is not messed up. Advocate the use of small water and ink thick practices, where the water little finger refers to the minimum amount of water that is required for the vacant sector of the layout to be inaccessible; the so-called ink thickness is also based on water, which causes excessive ink emulsification. The ink layer cannot be thick.