In the printing process, no matter what kind of printing, whether it is multi-color or monochrome printing, the primary problem encountered before printing is the deployment of ink color, so the ink color selection and deployment are often required. The deployment of ink color is the most important part of printing. The true reproduction of colors directly affects the product quality and market share. In some large-scale enterprises, there are not only specialized dispensers, but also the best. Make customers happy. Here's how to improve the quality of ink by using ink color mixing techniques:
Color matching principle
Each color is represented by the three characteristics of hue, lightness, and saturation, and thus the above three factors must be considered in the color matching process. Although black is theoretically the complete absorption of light, black ink still has a gloss. The ink is a mixture of pigment (toner) and resin binder. The pigment particles are surrounded by a layer of nearly transparent resin oil, which has a refractive and reflective effect on the light, so we can feel that the black ink still has a certain gloss on the substrate. The pigment usually accounts for 8-35% of the ink composition. Its amount determines the concentration of the ink, and has a great influence on the ink, such as the relative density, transparency, heat resistance, light resistance and chemical resistance of the ink. Wait. In the process of ink color matching, the ink used should be determined according to the actual printing process, the ink layer thickness, the printing substrate, and other conditions. When selecting the ink, the ink itself should be considered for its luster, hue, coloring power, and hiding power.
1) Gloss: Gloss can be measured either with the instrument or with the naked eye, and is usually observed with the naked eye only during the color matching process.
Gloss actually refers to the degree of the ability of ink printing to reflect light in the same direction after being irradiated with light, which directly affects the appearance of printing, which is a very important indicator. At the same time, when selecting the ink, it is necessary to distinguish whether the ink itself is bright, semi-glossy or matte type ink, and it should also be considered whether the ink is the same as the ink, such as ink or table printing ink. Must be prepared for the same ink to avoid mixing errors and cause unnecessary losses.
2) Hue is the basic feature of color, used for qualitative differences. When matching colors, the first thing to consider is whether the hue is the same. The detection method is usually scraped by scraping paper or analog printing, and the human eye compares the standard with the sample.
3) Covering power is the extent to which the ink covers its background. The better the hiding power is, the worse the transparency is, and the level of transparency affects the efficiency of the ink trapping and the degree of influence of the printed substrate.
4) Coloring power is a method to indicate the ink concentration, which is determined by adding a certain amount of ink and then adding a certain amount of standard white ink to dilute and then comparing with the standard sample. The coloring strength reflects the ink mixing degree. Affects the thickness of the printed film. Through the color identification (scratch paper scratch color test), you can compare the difference between the gloss, hue and hiding power of the ink sample and the standard sample.
The specific method is as follows: Put the standard ink in the upper left corner of the identification paper, and put the color ink in the upper right corner. Use a scraper to flatten the thinly-packed part at an angle almost perpendicular to the scraping paper and gently expand the thick-packed part with a slight inclination angle. After the surface of the ink is dry, the hue of the ink can be observed in the thin portion, and the hiding power and transparency of the ink can be identified in the black portion; the difference in luster between the two can be judged in the thick portion and the appearance of the entire color can be observed. Usually black and color inks are used. White scratched paper, while white ink uses black scratch paper.
It is best to compare the color samples during the daytime with an indirect light source in the room, and should not be exposed to direct sunlight. At night, it is recommended to use fluorescent tubes for color evaluation and the color temperature of 5000±200 K. You can also use self-made hybrid light sources: three 6500K400W fluorescent tubes, two 20W blue fluorescent tubes, and six 100W tungsten filament lamps to fix them Within a special hood, it is mainly for easy observation of color samples.
Color matching notes
1) Carefully observe the color samples, paying particular attention to the printed substrate, and select the ink from the rough and smooth reflectance of the substrate. For example, inks are printed on aluminum plates or cans that are very glossy and reflective, and the choice of highly transparent inks will help to greatly enhance the metallic luster of inks.
2) When selecting the ink needed for color matching, avoid mixing too much ink as much as possible. Use ink that is close to the standard color and made of a single pigment as much as possible. The color ink used for color matching is too much, the farther from the standard color, the lighter the brightness is. The higher the degree of matteness of the mixed colors, the impossible to use the color to modulate the primary colors. Therefore, it can be said that when two colors are used in color matching, three kinds are not used, and as few as possible.
3) Pay special attention to the tinting strength of the ink. If the selected ink concentration is not high enough, the standard color concentration cannot be achieved regardless of how the ink is dispensed.
4) When you need to add white or black ink, you should pay special attention to the accuracy of the added weight and weight. In all inks, the hiding power of white ink is very strong. If you add too much, it will not only dilute the color, but also stop the bottom. Material reflective degree. However, for the printing uneven substrate such as nylon cloth, cardboard, in order to ensure the appearance of printed products is best to print a white as the background color. Because the coloring power of the black ink is extremely strong and slightly careless, adding too much of it requires the addition of a considerable amount of other color inks to adjust the color, resulting in waste, and therefore requires special attention.
5) When making light color inks, determine how much white ink or varnish (dilution agent) should be added in order to adjust the degree of light transmittance of the ink film. It is absolutely not allowed to use solvents (dilution water) to dilute the color. Too much solvent will not only affect the printing performance, but also will destroy the ink structure, cause the separation of the pigment from the resin oil, precipitate, or greatly reduce the gloss and brightness of the ink. .
Wang Nengyou Institute of Printing Research, Hubei Tongshan Science and Technology Committee
Reprinted from: Guangdong Printing
China Senbo Industry Co.,ltd , https://www.yylpaper.com