High-grade ceramic decals fine screen printing technology (c)

4. The relationship between outlets and wire diameters

The screen used for screen printing of ceramic decals employs a polyester mesh of about 350 mesh. The intersection of the latitude and longitude lines of the screen forms a mesh hole, and the ink leaks from the mesh holes onto the flower paper. The size of the mesh and the wire diameter of the screen both affect and contain the printing effect of the dot. When a network of 100 lines, 120 lines, and 133 lines per inch rotates to a mesh of about 350 mesh, a certain part of the network points will be located on the mesh, while another part of the network will fall on the longitude and latitude lines. When the diameter of the dots is the same as the diameter of the screen, the dots covering the latitude and longitude lines are blocked by the lines and cannot be printed; when the diameter of the dots is twice the diameter of the screen, those covering each of the latitude and longitude lines Although some of the dots are blocked and some fall into the mesh, they are not able to print ideal dots due to the limitations of the ink penetration force; when the dots diameter is three times the diameter of the screen, even the dots that fall on the latitude and longitude lines have enough area. Located in the mesh, the dot printing effect is good. This issue cannot be ignored when setting the base dot size value range. The set range should be the range that can achieve good printing effect, the smallest dot should be three times the wire diameter. The way to calculate the diameter of the dot can first calculate the dot area, and then find the diameter. At present, common screens are calculated in inches, and dot area calculations are as follows:

Among them, DS: network area

X: screen lines per inch

h: the percentage of the dot area

The wire diameter of the screen can be found in the product manual. About 350 mesh screen diameter is 30 ~ 50μm.

The dot diameter of 120 lines per inch is shown in Table 1.

For analysis convenience, more than 60% of the outlets calculate the diameter of the white spot between the outlets. From the table, we can quickly see that when printing with a screen size of 350 μm with a wire diameter of 30 μm, for a good printing effect, the bottom screen dot should be set between 15% and 85%. In other words, 15% or less of small outlets and 85% of large outlets do not print well, and it is generally better not to use them. When using 350 mesh of 35μm screen printing, the bottom outlet is set at 20%. ~80% is good.

If the bottom screen dots are 100 lines per line and 133 lines per inch, the range of the percentage of the screen lines can also be determined based on the diameter of the used screens on the basis of the calculation of the percent dot diameter. The dot diameter only needs to be calculated once and it is recorded for inspection.

According to this method, when determining the percentage of the halftone dot area, it is necessary to consider the printing characteristics of the unit and the artistic processing needs of the original copy at the same time. If we say that according to the foregoing, the 350-mesh screen can allow printing of 85% of large outlets, and the printing conditions of the unit will expand by more than 75%, and the printing conditions cannot be improved temporarily. The high end is about 75%. In addition, despite the fact that under 15% of the printing of small outlets is not effective, when copying colors that gradually disappear from dark to light, the colors of flowers, such as flowers, imaginary rays, sky, and water, must be fully utilized. The. Because the original color itself is gradually disappearing, use 15% or less of the small outlets. When printing, the small outlets located in the mesh can be printed out, and the small outlets on the latitude and longitude lines can also be printed out more or less. More than 20% of the outlets with good printing effect can only strengthen the blooming effect of the color, prevent the color from suddenly disappearing, and enrich the subtle levels of the picture. Therefore, in this case, for the sake of artistic processing, the setting of the bottom outlets should start from a 5% small outlet.

With the continuous innovation of technology, continuous development of raw materials, continuous improvement of equipment, continuous improvement of operating skills, the characteristics of network printing, printing and printing will gradually become ideal, I believe that because of the desktop publishing system in the ceramic flower industry The application will make the setting of the network printing decals at the bottom of the ceramic screen more standardized and data.

(to be continued)