1. Toning. Before distributing ink, the amount of ink consumed for each color print should be calculated to make the appropriate amount of ink dispensed. Especially for two-liquid reactive inks, the amount of ink adjustment should be calculated according to its curing speed and printing speed.
In order to obtain the correct color, the ink adjustment should be carried out under stable natural light, and at the same time, it should not be counted and observed side by side to avoid the influence of illusion. When configuring fresh ink, the addition of dark ink should be gradually approached. Do not add too much at a time, and then use a lot of light ink to remedy. At the same time, the mixed hue should be reduced as much as possible. The more hue, the greater the gray scale.
In addition, it should also pay attention to the color change before and after drying. For example, on light-colored substrates with large ink absorption, the ink color after drying is often light; the color difference between the wet, dry and hair bubble of the foaming ink is large; The color of ceramic printing ink changes after firing; white ink will turn yellow after high temperature. Such color change laws require printers to accumulate experience and samples in practice to make their own color standards.
The color adjustment of screen printing ink (printing material) is a link that cannot be ignored in the process of screen printing. The basic principles of blending are inseparable from the basic principles of the additive method of colored light and the subtractive method of colored materials.
The three primary colors of the color material are mixed with any two colors in equal amounts, and a certain hue of the three primary colors of light can be generated. From the perspective of color, these three hues are called intermediate colors (or secondary colors). For example, green color formed by mixing yellow and cyan is an intermediate color. The hue produced by the mixing of intermediate colors and intermediate colors is called a compound color (or called a third color). The intermediate and multiple colors of the three primary colors are shown in Figure 3-60. Figure 3-60 Intermediate and multi-color mixture of three primary colors ink.
2. Ink toning method. The so-called color matching is to combine more than two colors, or use a small amount of colors in addition to the main color to form a color combination. When preparing the color ink before use, first expose the color to be prepared on the color sample separately, and correctly distinguish whether the original (or original) color is the primary color, intermediate color, or multiple color. If it is an intermediate color or a compound color, it is necessary to distinguish the ratio of the main color to the auxiliary color. Secondly, it must be adjusted according to the color indicated by the original, and the sample is debugged. When the color difference between the color and the original is small or equal, it can be deployed in large quantities, and the time should be short and the amount should be adjusted appropriately. Too little adjustment will cause downtime and the ink color will be different, which will affect the normal production. Too much will cause unnecessary waste. Ink adjustment is usually carried out in a place where the light is stable or the light is not directly irradiated.
There are three points to be noted when screen printing inks are to be mixed: a. When adding ink, different colors of ink should be added as little as possible. The less color inks, the better the mixing effect. b. Adopting the principle of "from light to deep", no matter preparing light or bright color inks, when the hue is close to the model, be careful. It is better not to mix and call inks produced by different manufacturers. Try to use inks of different colors from the same manufacturer for color mixing. Otherwise, uneven color tone will occur. In severe cases, condensation will occur and the ink will be scrapped. c. Some screen printing inks are dried by drying. The light-colored drying is lighter than the un-dried, and the dark-colored drying is darker. In addition, whether the color tone of the ink is different before and after drying during printing is a problem that is easily overlooked. Generally speaking, through natural drying (solvent volatile ink), the substrate is plastic, metal, paper, glass, etc., the color will not change; but if it is a ceramic color material, it will develop color after burning and oxidation. , Can only be adjusted based on experience. For silk screen inks that are dried by heat-setting and light-setting, the color changes in depth, as mentioned above. When the amount of ink adjustment is large, you can use the ink adjustment machine to complete the color adjustment in a short time. The original ink colors are mixed in different proportions, and many colors of ink can be prepared, as exemplified in Table 3-15.
Examples of ink color formulations Primary color synthesis ratio Chroma magenta yellow cyan 050500: 1: 1 green 500501: 0: 1 blue-violet 5050501: 1: 1 black 257501: 3: 0 dark yellow 025750: 1: 3 dark green 752503: 1: 0 Orange Red 080200: 4: 1 Apple Green 10025254: 1: 1 Red Brown 25251001: 1: 4 Dark Green
The preparation of light-colored inks is generally based on white inks, with appropriate color inks. Such as light blue, mainly white ink, slightly blue (cyan); light red, mainly white ink, slightly red; gray, mainly white ink, slightly black; silver gray, mainly white ink, slightly Add silver powder paste, and then add trace black ink. When preparing light-colored screen printing ink (printing material), white ink should be added as little as possible, because white ink has high activity and it is easy to cause discoloration of other colors.
To adjust the ink, the screen printing worker must: a. Understand the specifications and performance of the ink; make the matched ink suitable for production needs. b. Master the basic knowledge of chromology and use it freely in ink adjustment. c. Analyze the printing color and process technology to find out the color sequence of multiple sets of colors, so as to avoid the color sequence is wrong, the two colors are mixed, and the color changes. d. Pay attention to the brightness of the ink color when adjusting the ink. It is required that the brightness should be adjusted with the original color as much as possible. Otherwise, the transferred ink will be "grey" and reduce the original color brightness. 3. Adjustment of ink printing suitability. Generally, the viscosity of the screen printing ink is slightly higher. The user should use the appropriate solvent, thinner, surface according to the characteristics of the printed image, the screen mesh number, the printing speed, the workshop temperature, the surface tension of the substrate and the ink absorption performance. Active agent and viscosity reducer, etc., comprehensively adjust the viscosity, surface tension, fluidity and drying speed of the ink. For example, when printing thin lines and dots, the fluidity of the ink should be slightly lower, and the drying speed can be slower; when printing on a coarse screen, the viscosity should be slightly larger, and the drying speed can be faster; when printing at high speed, the fluidity is slightly larger, and the drying speed can be It is slightly faster; when the workshop temperature is high, the drying should be slower and the viscosity slightly higher; when the surface tension of the substrate is small, the surface tension of the ink should also be smaller; when the ink absorption of the printing surface is strong, the fluidity and surface tension of the ink can be large The drying speed can be slower. Appropriate adjustment techniques also depend on practical experience.
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