The most popular halftone screen printing technolo

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Halftone silk printing technology point calculation method (I)

template control is particularly important when using three primary colors printing. Because the inks have a certain degree of transparency (especially UV inks), coupled with the template deviation, the thickness of the printing ink film changes, resulting in a significant shift in the printing color

this color shift can be described by the absorption of light (i.e. optical density) by the ink film. The optical density can be obtained by measuring the printing color with a densimeter. The measurement results are displayed in logarithmic form. It can also be said that this number represents the ratio of the light absorbed by the "absolute" white material to the light absorbed by the tested ink

"normal ink volume" is a term used to describe the correct optical density printed with a specific ink and substrate. The printing materials with relatively accurate ink volume (the color is visually correct) measured by densitometer can be used as a reference for printing or proofing under the same ink and substrate conditions. Using this method, you can detect the change of color, and ensure that the printing quality is maintained within the tolerance range of foam granulator, which can be connected to microcomputer controlled electronic universal experimental machine

the color we feel is not only related to the size of the printing point, but also related to the thickness of the ink layer. The size of eye opening, wire diameter, template thickness, ink type and ink viscosity will all affect the ink layer thickness

we know that the wet thickness model of the ink layer: Wes ⑶ 00B degree is equal to the theoretical color value of the silk fabric, which is usually provided by the manufacturer. For example, a theoretical color value of 20 cc/m2 will form a wet ink layer thickness of about 20 microns. The ink layer thickness can be calculated simply by dividing the color value by the hole area according to the following method: ((20 cubic centimeters ÷ (100 centimeters × 100 cm)) × 10000 μ M/cm) = 20 μ M

the thickness of the template film also affects the thickness of the ink layer, and the thickness must be increased according to the silk color value. Therefore, on a wire, using a template with a thickness of 10 microns and a theoretical color value of 20 cubic centimeters/square meter, a wet ink film thickness of approximately 30 microns will be formed, which is 10 microns more than the above calculation results. In order to print fine halftones, choosing silk fabrics with low theoretical color value is as important as using thin film

before establishing quality control parameters, it is also necessary to measure template characteristics, such as thickness, surface roughness, etc. Once accurate and acceptable values based on printing are determined, a standard plate making process should be established to ensure that the same template characteristics can be obtained constantly

under the condition that there is no same benchmark for silk printing, many enterprises have established production standards and their deviations without considering their respective conditions. Because there is no objective quality control conditions, it makes many silk workshops produce inaccurate and unpredictable printing colors in printing. In fact, this can be completely avoided, because the silk printing process can be controlled by a series of measurable parameters. You can measure these parameters and get the desired color reproduction standard

in addition, it can help you obtain accurate and consistent colors, help you improve the overall quality of printing, and enhance the stability of product reproduction in printing. When establishing the standard, the following parameters should be mainly considered:

1. printing point and tone range

2. Ink layer thickness

3. Optical density of printing color

4. Point expansion and loss

5. Ink overprint

the first two parameters are mainly affected by the quality of silk fabrics. Choosing the right silk diameter is as important as using the right silk fabric and mesh. In addition, in order to ensure the consistency of printing quality standards, you should learn how to calculate the deviation values of these parameters

other parameters are affected by some measurable factors in plate making and printing, and the above five parameters will be briefly described in subsequent issues

although some factories establish standards and tolerances to guide production in specific production processes, the same standards do not exist for the silk printing industry. As a result, some silk printing plants tried to print halftone products without objective quality control. The result is that the accuracy is not enough to achieve the expected color. However, this is not the reason, because the silk printing process is controlled by a measurable Chinese side, which takes the development of China Mongolia relations as the priority direction of foreign policy, and can improve its own color reproduction standards through measurement and use

in addition to helping you achieve accurate colors on a constant basis, establishing quality control standards can also help manufacturers comprehensively improve printing quality, improve the reproduction stability of the whole printing process, and ensure the repeatability of the same or similar work. In the process of improving the standard, the most basic variables that need to be considered include the following:

* printing point size and gradient range

* ink layer thickness

* optical density of printing color

* point increase and point loss

* ink overprint control

the first two variables are mainly affected by the screen fabric used, and you will see that choosing the correct fiber diameter is as important as using the correct fabric and hole number. You can also learn the calculation method of tolerance related to these variables to ensure consistency with quality standards. The remaining variables are affected by other measurable features of screen production and printing. You will find out how to better evaluate these variables. (to be continued)

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