The influence of the printing process on the color

1, dry retreat density difference

On the same paper, the proof density just printed is higher, and after a certain period of time, the proof density decreases as the ink's dry smoothness decreases. Due to the different density values ​​of the ink layer before and after drying, the color tone of the printed image is also different. For the freshly printed product, the ink is still wet and has a difference from the dry state. This is because the ink layer just printed has a certain leveling property, so the surface reflection is dominated by specular reflection, which looks bright and shiny. When the ink layer is in a dry state, the reflection of the surface is dominated by diffuse reflection, and the color is naturally dull and darker than when it was printed. Therefore, the general print proofs are slightly darker than the standard proofs. However, how much deeper is the use of data control? When proofing, determine the density values ​​of various colors that have just been printed. When printing, refer to these density values ​​for printing. The color of the ink is nearly the same.

2, printing speed

As the printing speed increases, the contact time between the printing surfaces will be shortened, the dots will become imaginary, the ink transfer rate will decrease, and the printing quality will decline. In order to ensure the full contact of the printing surface and improve the printing quality, it is required to control the printing speed under a certain printing pressure in order to obtain a stable ink layer thickness.

3, ink thickness and ink balance

The control of ink hue in the printing process is mainly achieved by controlling the thickness of the ink layer. When the thickness of the ink layer changes by about 0.1 μm, a color difference of ΔE=1.5 to 4.5 NBS is caused. Obviously, this effect is significant. Offset ink reproduction and ink balance are closely related. Under the same ink conditions, water and water will affect the depth of color. It is important to properly understand the ink-water balance and pay particular attention to the pH of the wetting fluid. The principle of water consumption is to keep the amount of water supplied as small as possible when it is not dirty.

4, printing pressure

The size of the printing pressure has a great influence on the degree of transfer of ink from the printing plate to the paper. When the printing pressure is insufficient, the ink is not transferred enough and is not suitable for printing; when the printing pressure is too high, due to the printing plate The spread of ink to blank parts other than those in the graphic and graphic text shows that the ink transfer rate has not been improved, and it has also brought other ills. It is also not suitable for printing. Only in the appropriate range of printing pressure can print printed materials with thick ink layers, clear images, rich gradations, and good color reproducibility.