Process Technology Control Essentials for Color Printing

Whether it is offset printing, gravure printing, flexo printing, printing of cartoned paper, offset printing (printed corrugated cardboard) or flexo printing, the production process of direct printing of corrugated cardboard, in order to make the product's spot color printing If the originals are the same, the ink must be accurately blended. It can be said that the quality of ink dispensing work not only affects the performance of machine production, but also directly affects the printing quality of the product. Therefore, the correct deployment of good color printing inks, and the correct grasp of color knowledge and ink transfer process techniques are very important technical control links in production.

Use the principles of three primary colors to prepare inks

The colors yellow, blue, and red are the most basic colors in the chromatogram, which is what we are used to calling the “three primary colors”. Tricolor is the basic color of any color, that is, no matter what color, it is always within the scope of the three primary colors. Therefore, the use of different proportions of the three primary colors can be deployed innumerable kinds of colors. The hue change of the ink is the use of the change rules of the three primary colors, such as the equal mixing of the three primary inks to obtain a nearly black color; the two primary colors of the three primary inks are equal or unequally mixed to obtain various colors. The hue is biased towards the ink with a high content ratio; if the two primary inks are mixed and formulated in equal amounts, they can become standard inter-colors. The three primary color inks are mixed and prepared in various proportions to obtain a variety of complex colors. The above-mentioned primary color inks are formulated into various colors, which are obtained according to subtractive color theory of the three primary colors. Therefore, using the principle of three primary colors to mix inks, various spot color printing inks can be easily formulated. The three primary colors inks are mixed in equal amounts and added with different proportions of white ink to be formulated into light inks of various shades. After any color ink is added with black or other dark ink, its brightness decreases accordingly and the hue becomes darker. dark. On the contrary, if white ink or diluting agent is added, the brightness will increase accordingly. The deployment of any hue is based on the three primary colors, and the diluting agent only adjusts the darkness of the hue.
Based on 10 basic dark color maps

The 10 basic dark color maps refer to the most simple, straightforward, and intuitive arrangement of the saturated three-primary inks, allowing them to be mixed in equal amounts into a representative dark ink, which is also the most common color in spot color ink formulations. These basic dark colors can be divided into three types according to the number of mixed primary inks. There are 10 types in total, including the three primary colors of yellow, magenta, and cyan (usually denoted as Y, M, and C) plus three different colors of red, green, and blue. (R, G, B) plus four complex colors of purple, bronze, olive green, and black (BK). The 10 basic dark color maps are composed of three equilateral triangles of different sizes. The inner triangle is the primary color layer, and the three vertices are the primary colors. The middle triangle is a mesochromic layer, and the three vertices are inter-colors mixed by the equal amounts of adjacent two primary colors, such as Y+M=R. The large triangle is a complex color layer, and the three vertices are the complex colors obtained by mixing the two adjacent colors equal to each other, and are also the results of mixing the three primary colors in different proportions, such as R+G=(Y+M)+(Y+C). ) = 2Y + M + C = bronze. The black at the center of the triangle can be obtained by mixing the three vertex colors of any layer in equal amounts. Although there are innumerable kinds of color ink hues, the ever-changing colors are almost similar to each of the 10 basic dark colors. As long as we understand and master the interrelationships of these 10 basic colors, we can lay a solid foundation for accurate and rapid deployment of spot color inks.

Formulation of inks based on print chromatography

Depending on the color of the printed chromatogram, the ink is more intuitive to find the color. However, if the color and gloss of the printed paper and paperboard are different from those of the chromatogram, the color control will produce a certain amount of error. Therefore, the color ratio of the chromatogram can generally be used as a reference. As long as the general hue is found, the color and proportion of the ink provided by the chromatogram can be referenced, and the ink transfer program can be mastered as appropriate. Each color block in the chromatogram has the area percentage of the original color dot. You can refer to these values ​​to determine the proportion of each color ink in the original color sample. The calculation can be used to determine the amount of ink used, that is, the unit area, the removal of the three primary colors, the remaining area of ​​white paper is the white ink content. If the standard color sample is similar to the light blue spot color formed by 30% blue dots, the calculation method is: C:W=30%:(100%-30%)=30%:70%=3:7. Then, When blending, it is to use light blue 3 parts and white ink 7 parts to mix light blue.

Master the three attributes of color and other color-related knowledge

Whether it is printing production personnel or professional ink transfer personnel, mastering the basic knowledge of color is the foundation for good ink transfer.

Master the three attributes of color

Brightness, purity, and hue are the three attributes of ink color, and they are also the basic factors that affect the quality of printing ink color. The lightness of a color refers to the degree of lightness and darkness of the human eye, and corresponds to the reflectance of light. The brightest is white, and the darkest is black. The gray between black and white is formed by the interval of brightness degree intervals. The 10 levels of lightness are represented by numbers 0-10. In the spectrum of seven colors, the order of brightness from high to low is yellow, orange, green, cyan, red, blue, and violet. Brightness can give people a feeling of openness and openness, and low-levelness gives people a feeling of simplicity and lowness. For different uses of color cartons and other packaging products, spot color layouts are often based on the characteristics of the product and the user's requirements for color brightness to determine the brightness of the color. If the lightness is higher, add a little dilute agent or white ink, and vice versa, add a dark ink. Purity refers to the degree of vividness of ink color, also known as color saturation or saturation. The size of the ink color depends on the ratio of the pigment component to the binder or the solvent. Therefore, when the high-purity ink is added with an auxiliary agent, water (water-based ink) or white ink, its purity is reduced. The purity of the same ink color, due to the different surface gloss of the substrate, the results of the color purity will be different, such as the same ink printed on the high smoothness of the cardboard and the rough surface of the cardboard, the former The printed color is much brighter than the latter.

Therefore, in order to improve the vividness of the printing of carton products, the degree of vividness of printed products can be improved through the processes of coating and polishing. The hue of the ink color refers to the appearance characteristics of the color, which is determined by the dominant wavelength of the colored light. The main hue of the color is usually: white, yellow, green, blue, red, gold, purple, black and so on. In addition to the black ink does not exist in the hue of the hue, other colors will have the problem of hue of the hue, such as the yellow with a reddish phase, bluish equal. The same ink hue, due to the difference in the color of the cardboard surface, the color will be different after printing, especially white cardboard, white cardboard, in fact, they are not pure white, often yellow with yellow or blue phase; White with red or green with equal. The author has deep feelings in the production process practice for many years. Therefore, when the same spot color ink is used, due to the difference in hue of different batches of cardboard surface, the hue of the ink is often re-adjusted so that the printing hue can meet the requirements of the sample draft. The practice of the production process shows that the brightness, purity, and hue of the ink color are complementary. As long as one of the attributes changes, the other two attributes will change. Therefore, it is necessary to pay attention to the correct grasp when adjusting the ink.