The color reproduction of packaging and printing is discussed in detail (below)

Effective color management is the guarantee of the quality of the entire copy, but the final product is obtained through ink. As one of the five major elements of printing, ink has an important influence on the printing process and quality. Correct and reasonable use and deployment of ink is the key to ensure accurate color reproduction.

Use of ink

Composition and properties of inks: Water-based inks are made from water-soluble resins, high-grade pigments, solvents, and additives. The hue depends on the nature of the pigment and generally requires that the pigment has a bright color, proper coloring power and hiding power, good resistance and a high degree of dispersion. In order to obtain good printability of the ink, it is often necessary to adjust the ink fluidity, drying property, and stickiness according to different conditions using various ink additives. There are many factors that determine the quality of ink and ink, and if it is used improperly, it will bring a series of quality problems. During purchase and use, attention should be paid to analysis to determine the status of the merits, and adjustments should be made according to the situation to ensure its excellent printability. .

In printing, the ink has a certain viscosity is necessary to maintain the normal transmission, transfer of ink. Therefore, the viscosity of a high-grade ink is generally controlled to be about 20±5 seconds, and the difference in viscosity will cause the printing color to have different shades. In the actual production process, the PH value of the ink on the machine can be adjusted or controlled between 8.0 and 9.5, depending on the product and the temperature.

Ink blending: Ink blending mainly refers to the ink color deployment. In the printing of packaging products, the color adopted by the ink and ink is based on spot color on the spot, achieving both visual and anti-counterfeiting effects.
These different spot colors cannot be overprinted by the four colors of blue, green, yellow, and black, and they cannot be directly used for the original ink. The technical personnel must obtain different proportions of the original ink according to the production conditions. .

The color deployment of ink is based on the principle of subtractive color, that is, any color can be prepared by mixing three different proportions of the three primary colors, and considering the three basic attributes of hue, lightness, and saturation. In the color matching, the ink to be used should be determined according to the actual printing process, the ink layer thickness, and the printing substrate, and the factors such as the hue, gloss, coloring power, and hiding power of the ink itself should be taken into account.

Color matching process

Analysis of the original color: Toning is performed on the color sample of the original. In order to reduce the blindness of the toning, the color of the original must first be analyzed to determine the hue and proportion of the original color ink. Analysis of the manuscript is mainly the use of instrument color measurement and human eye color than a combination of methods. The use of printing chromatography to determine the ratio of three primary color inks is relatively simple and practical. The three primary color inks and white ink content can be calculated based on the percentage of the primary color dot area marked in the chromatogram.

Color Matching: According to the calculated ratio, a small amount of primary color ink is weighed for deployment. Note that when the color of the ink is compared with that of the original, when both colors are close to each other, it is preferable to adjust the ink to make a contrast on the scratch paper, and so on until the two colors are completely the same. When colorimetric, the ink should be uniform, and the thinner the ink layer, the better. To ensure the accuracy of the color hue, the paper should be the same as the paper used for printing. The adjustment of brightness and saturation is achieved by adding white ink and black ink. When adding white or black ink, special attention should be paid to the accuracy of weighing.

After the ink to be dispensed reaches the requirements of the original document, batch inks can be formulated in proportion. The amount of ink used for a batch of jobs is usually determined by the type of paper, the image area, the number of prints, and the amount of wear, and it is based on the principle of less.

Record: After the preparation is completed, the ratio of various inks used in the ink transfer, ink transfer, dry oil, ink type, quantity, and manufacturer information will be registered in detail, which will be used as a reference for later ink dispensing.

Other considerations: When analyzing originals and color comparisons, it is best to use a standard light source or a light source that is close to sunlight. Care must be taken to wait for the ink film to dry before performing colorimetry to reduce visual errors. Try to use color inks that are close to the original color ink or other single color inks. If the color inks used in the color matching are too much, the brightness and saturation will be worse, which will affect the printing effect. Therefore, the fewer the number of inks when matching colors, the better. It is best to choose the ink products of the same manufacturer.

When coloring, we must fully understand the daily printing speed and printing pressure of our equipment and control the ink viscosity. Different printing speeds and pressures will have different shades of printed matter. Therefore, ink formulated at a low speed must wait for the printing speed to open to the normal speed and then check the original again to avoid chromatic aberration and waste.

After the ink is transferred out, if it is found that there is an error between the color sample and the original printed on the machine, it shall be promptly corrected. The ink fountain and the ink roller should be cleaned when changing color to avoid unclean cleaning and color cast. The remaining spot ink after printing can still be prepared according to the hue of the new manuscript, but often the saturation is grayish, especially the remaining ink that is retrieved from the ink fountain is likely to have been emulsified or the printability has changed.