Experience of ink color allocation in the most pop

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Experience of ink color allocation in the printing process

in the printing process, no matter what kind of printing method, multi-color or monochrome printing, the primary problem encountered before printing is the ink color allocation to meet the needs of the printed products. Therefore, it is often necessary to select and allocate the ink color. No matter how bright the ink is, if the operator does not understand some ink performance and color matching knowledge, the mixed ink can not achieve a satisfactory appearance and due quality level. To this end, this article would like to introduce some color matching methods for reference

I. color matching principle

any color is represented by three characteristics: hue, lightness and saturation. Therefore, the above three factors must be considered in the color matching process. Although in theory black is the complete absorption of light, black ink still has luster. Ink is made by grinding pigment (toner) and resin binder. A layer of almost transparent resin oil is wrapped around the pigment particles. This layer of resin oil has refraction and reflection effect on light, so we can feel that black ink printing still has a certain gloss on the substrate. In the process of ink color matching, the ink used should be determined according to the actual printing process, ink layer thickness, printing substrate and other conditions. When selecting ink, consider the gloss, hue, tinting power and hiding power of the ink itself

1. gloss

gloss can be measured by instruments or judged by the naked eye. Usually, it is only observed by the naked eye in the process of color matching. Gloss actually refers to the degree of the ability of ink printing samples to reflect light in the same direction after being irradiated by light. It directly affects the appearance of printed matter and is a very important indicator. At the same time, when selecting ink, it is necessary to distinguish whether the ink itself is bright, semi gloss or matte ink to avoid mixing errors

2. hue is the basic feature of color. It is used for qualitative difference. When matching colors, it is necessary to first consider whether the hue is consistent. Its detection method is usually to scrape the color with scraping paper or carry out simulated printing, and observe and compare the standard sample and the sample with human eyes

3. hiding power is the degree to which ink covers its background color. The better the hiding power is, the worse the transparency is. The transparency affects the efficiency of ink chromaticity and the degree of influence by the printing substrate

4. tinting power is a method to indicate the ink concentration. The determination method is to dilute and mix a certain amount of ink with a certain number of times the amount of standard white ink, and then compare it with the standard sample. The color difference strength reflects the color mixing degree of the ink and affects the thickness of the printing ink film

the difference in gloss, hue and hiding power between the ink sample and the standard sample can be compared through the drawdown test of the color identification scraping paper. Specific methods: put standard ink in the upper left corner of the identification paper and color matching ink in the upper right corner. The distance between the two is about one centimeter. Use a scraper to flatten the thin part at an angle nearly perpendicular to the color scraping paper and quickly unfold the thick part with light force at an inclined angle. After the ink surface is dry, the ink hue can be observed in the thin part, the ink coverage and transparency can be identified in the black belt part, the gloss difference between the two can be judged in the thick part, and the whole color appearance can be observed. Generally, white scraping paper is used for black and color inks, while black scraping paper is used for white inks

II. Problems needing attention in ink color matching

1. carefully observe the color sample, pay special attention to the printed substrate, and select the ink from the roughness, smoothness and reflection of the substrate. For example, the ink is printed on a smooth and highly reflective aluminum plate or can. Choosing an ink with high transparency will help greatly enhance the metallic luster of the ink

2. when selecting the ink required for color matching, try to avoid mixing too much ink, and try to use the ink close to the standard color and made of a single pigment. The more color ink is used for color matching and the farther away from the standard color, the worse the brightness is, and the higher the matte degree of the mixed color is, so it is impossible to modulate the primary color by color matching

3. pay special attention to the coloring power of the ink. If the selected ink concentration is not high enough, no matter how it is combined, it cannot reach the standard color concentration

4. when white and black ink need to be added, special attention should be paid to the weight added by the power station and the accuracy of weighing. In all inks, white ink has a strong hiding power. Adding too much will not only dilute the color, but also prevent the reflective degree of the substrate. However, Mitsubishi materials, a Japanese nonferrous metals giant, bows to apologize for responding to counterfeiting. When brushing uneven substrates such as nylon cloth and cardboard, it is best to print a layer of white as the background color to ensure the appearance of the printed products. Due to the strong coloring power of black ink, it is necessary to add a considerable number of other color inks to adjust the color according to the requirements of Jinan testing machine factory, resulting in waste. Therefore, special attention should be paid

5. when making light color ink, judge how much white ink or ink blending oil (diluent) should be added to the ink film from the light transmittance. It is absolutely not allowed to use the solvent (dilution water) to dilute the color. Too much solvent will not only affect the printing performance, but also damage the ink structure, resulting in the separation of pigment and resin oil, precipitation or greatly reduce the gloss of the ink

6. methods to improve the gloss of printing ink film

(1) add an appropriate amount of ink blending oil within the allowable range of color concentration

(2) apply a layer of varnish or inking oil on the surface of the printing ink film

(3) increase the transparency of the ink. For example, select high transparency ink or add an appropriate amount of ink blending oil, and use the reflection of the smooth and strong reflective substrate to increase the gloss

(4) prevent the substrate surface from adsorption and reasonably improve the smoothness of the substrate printing surface

(5) pay attention to the temperature and humidity of the printing environment. In the case of high humidity and low temperature, during plastic gravure printing, due to the fast volatilization of the solvent (usually the surface of the ink film is dry within 1 minute), the water vapor in the air around the ink film is rapidly condensed due to the absorption of heat around the ink film, resulting in the formation of fog on the surface of the printing ink film, resulting in the loss of gloss of the ink layer. In the plum rain season, special attention should be paid to controlling the temperature and humidity of the printing environment to ensure good printing effect

7. fluorescent inks cannot be mixed with a large number of non fluorescent inks, otherwise the fluorescent effect of the ink will be lost

III. special color production

1. gold and silver ink production: use ink mixing oil to add an appropriate amount of gold powder and silver powder and stir them evenly. Pay attention to the selection of gold powder and silver powder with appropriate fineness. At the same time, select the ink mixing oil suitable for the printing substrate and prepare it during printing to prevent the ink from sedimentation and stratification due to long storage time. 2. Before the experiment, estimate the maximum load of the experiment. Gold ink can also be mixed with silver powder, transparent yellow and ink blending oil

2. pearlescent ink: the pearlescent pigment is evenly mixed with a suitable proportion of high transparency ink or inking oil. The covering power of the ink is strong, and it is likely to lose the pearlescent effect

3. luminous ink: the ink has the effect of emitting light after absorbing light energy for a certain period of time, so it often emits light at night, so it is called luminous ink or phosphorescent ink. Usually, noctilucent pigments are dispersed in a high transparency inking oil and stirred evenly

none of the above inks can be ground. The grinding of gold ink and silver ink will damage the grinding equipment, and the grinding of pearlescent and luminous inks will damage the surface or crystal structure and lose its due effect

source: keyin report

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