Spot ink preparation

Printing can be used to print colorful prints by using tricolor inks (yellow, magenta, cyan) and black ink. However, some product colors can hardly achieve the effect of thick and bright colors through common composite dots, or from the process and cost. Considering that it is not necessary to perform separation or multi-color printing, monochrome can print special color effects required by the original color sample. This requires the printing of spot color inks, such as the printing of large-area solid blue on the Speedpost envelope, because the requirements The color is bright and thick, it is difficult to achieve the color effect of the manuscript with four-color printing, it requires spot color blue printing, in addition, some book covers, envelopes and letterhead paper micro-standards, because of high quality requirements (thick field), the number of production Small, short time, low cost, only use color ink printing without separation, to meet the requirements of users.
Ink manufacturers cannot and do not need to make a variety of hue inks. They only produce several commonly used inks (such as four-color ink, gold red, big red, medium blue, etc.). According to the user to provide the original color sample, with two or more original ink for deployment to obtain a new hue of ink, this process is the deployment of spot color ink.
In production, there is currently no simple, highly-operational color analysis and testing instrumentation equipment. Basically, the experience of the ink-transferring personnel is the main reason. Because the ink-transferring personnel have not grasped the spot-color ink deployment technology well, it often causes a good adjustment. The improper ink quality or the ink on the machine did not find the hue and then redeployment, resulting in quality accidents, waste of ink, worker labor repeatedly, time delays and other unnecessary trouble, which requires us to have a full understanding of spot color ink deployment technology And grasp.
Spot color ink deployment principle and spot color ink principle of color spot color ink deployment is based on the original color sample, according to the principle of ink tricolor subtractive color deployment. The physical effect exhibited by the ink's pigment is called the subtractive method, which means that when the pigment shows a certain color, it means that the pigment selectively absorbs various colors in the white light spectrum (minus the color light).
The color change law of ink tricolor subtractive method is as follows:
Magenta+Yellow=Red Magenta+Cyan=Purple Cyan+Yellow=Green Magenta+Cyan+Yellow=Black So the mixing of the ink pigments is a weakening of the light green, which is a phenomenon of color reduction. The more pigments are mixed, the last color is The darker and nearer black.
The color rendering principle of spot color inks is that the ink pigments exhibit effects through the principle of subtractive color. For example, when the yellow and blue inks are formulated in the same amount, since the pigment in the printing ink is the main body of ink coloring, the particles are very small, and the insoluble suspension is 0.01-0.5um in diameter. We will print the prepared ink on paper and To make a partial enlargement, when the white light is irradiated, there may be three situations. I: When the white light is irradiated on the yellow ink particles, it absorbs the blue light and reflects the red and green light. II: When it is irradiated on the blue ink particles, it Red light is absorbed, green light and blue light are reflected; III: When irradiated on yellow and blue mixed ink particles, it absorbs red and blue light and reflects green light.
Due to the equal blending of yellow and blue ink, the chances of II and III are equal and the reflected light is as follows:
I: W-B-R=G
II: W-B=G+R
III: W-R=B+G
The reflected light combination effect is:
3W-(2B+2R)=3G+R+S=W+2G
Therefore, the color of these two inks after blending is green. If the yellow ink and the blue ink are not equal blends, then the II and III conditions are unlikely to be equal, and the yellow ink will make the ink yellowish, and vice versa. After grasping the law of the color change of the three primary colors, it is possible to draw inferences about the colors of various manuscripts.
How to deploy spot inks for the deployment of spot inks, ink changers need to make three preparations: 1. Hue deployment is accurate, in line with the original color standard; 2. Formulation ink printing accuracy is accurate; 3. The number of spot color inks is accurate.
Hue deployment is accurate 1. The ink transfer personnel should have a deep impression on the colors of the various inks produced by the ink factory, and have a keen sense. Ink transfer personnel should have a thorough understanding of the three properties (hue, lightness, saturation) of various inks, and the color matching can be adjusted to the spot color inks in accordance with the original color sample with the fastest time and with the least original ink type. Because the color can be used to study its properties through the three parameters of hue, lightness, and saturation, and as a basis for measuring the difference between two colors, use it to express the description of the color to obtain a unified color language, which is suitable for the requirements of normalization and dataization.
2. A. Determine the primary and secondary color inks for the original color sample. The deployment of spot color inks is the key to the analysis of the original color samples after we have mastered the color change patterns and characteristics of several common inks. It is related to the accuracy of the entire ink hue, and we can use the subtractive color method to analyze the hue of the original. The principle to be considered is to analyze the content of the original color sample in the three primary colors by the three primary color theory to determine the ratio of the primary color and the secondary color. Generally, one primary color is the primary color, and other colors are secondary colors.
When preparing China Telecommunications Corporation's standard color telecommunication blue, through observation it gave us the impression that the blue-based color is slightly red and the color of the entire ink is bright and thick, pure, that is, the brightness, saturation, and hue of the ink are pure, so we The use of sky blue, supplemented by bright, violet purple ink, although the color separation on the proofs ratio, but it is electronic color separation or color matching on the desktop system is not compatible with the actual printing ink.
Formulating China Mobile’s mobile blue, because its standard color is printed on the printing press, it will have obvious color cast, increase the gray scale, giving people the feeling of staleness and darkness, so we can't stop at the difference between it and telecommunication blue. Few color separation ratios, but the use of hue is not pure, the darkness of the dark blue in the main color, and red, and then slightly black ink to increase the gray scale of the entire ink.
b. Obtaining the ratio of the main and auxiliary color inks After we determine the main and auxiliary colors, the main and auxiliary color mixing ratios are obtained mainly through the following ways: According to past experience, the proper ratio is obtained; according to the similar color samples in the inking manual Than; with a small amount of original ink to adjust the sample to get the correct ratio.
c. Match the color of the spot color ink with the original color sample. Use paper (usually coated paper, offset paper). Draw a small amount of spot color ink to obtain the ink using the “scrape method” or “topography method”. The sample is compared with the original color sample to adjust the ratio when there is a difference.
Precautions for color matching:
The light source for color recognition is the ideal white light, the natural light facing the north window, and the artificial light source similar to the natural light, such as the fluorescent lamp and the incandescent lamp mixed with the light source;
- The ink color sample prepared is darker than the original color sample. Because the offset ink is mixed with the fountain solution and the ink is dried, the ink hue will become lighter. Also has the correct hue, ink deep (saturation), can reduce the amount of ink, which is beneficial to offset printing ink control;
- Consider the properties of the substrate, such as whiteness, absorbency, smoothness, etc. If the nature of the paper is far from the paper nature of the original, analyze it according to the specific situation. If it is also telecommunications blue, but Sub-users require the use of pink fragrant cards to print telecommunications logos. If telecommunications blue inks are used, the printed colors will be dark and gray. The entire hue is far from the original, and we can print directly using sky blue ink. The effect of color matching with paper is similar to Telecommunications Blue.
- Consider the influence of the environment surrounding the color sample to avoid illusion of color. When color is identified, the surrounding color should be covered off. Single observation will not cause color shift.
——When the ink layer is obtained by the topography method and the scraping method, the thickness of the ink layer of the spot ink must be similar to that of the original color ink layer.
The printability of spot-color inks requires proper and accurate printing properties of general spot-color inks. The main considerations are the viscosity, flowability, and dryness of formulated inks. However, with the development of the ink industry, the suitability of various inks is better. Better compatibility, generally we do not need or need to add appropriate amount of ink additives, such as special ink additives or varnish, to change the compatibility of formulated ink, you can achieve better printing results.
Matters needing attention: Ink mixing should be mixed evenly; Paper properties such as coated paper, ie coated paper, are generally prepared with quick-drying ink, and offset paper can be formulated with resin ink.
The amount of spot color inks to be dispensed accurately and accurately adjusts the amount of ink. The following factors are mainly taken into account: how much is printed; the importance of paper absorbency; the area of ​​printed graphics; the strength of spot color printing ink; the thickness of spot ink (density Size) and so on.
If the ink is over-provisioned, the remaining ink will be wasted. If too little is not enough, it will need to be deployed again. If complex colors are encountered, the inks for the second and first deployment are difficult to be exactly the same. influences. Therefore, the actual printing amount should be slightly more than the actual printing amount. This is also to avoid the change in the ink color of the ink after the stock in the ink fountain is lower than a certain value.
The deployment of dark inks and light inks can be generally classified into dark inks and light inks.
The deployment of dark ink only uses the original color ink deployment, does not add any diluting agent, collectively referred to as dark ink deployment, according to the analysis results of the color sample, the determination of the main and auxiliary colors, and then according to the design ratio, with auxiliary color Ink is added to the main color ink and mix well. According to subtractive color theory, the type of primary color ink should be used as little as possible when mixing ink, otherwise it will reduce the brightness of the ink and affect the vividness of the color.
Light-colored inks are formulated with inks formulated with dilute agents, which are collectively referred to as light-colored inks. Because light-colored inks have less stimulus to the human eye, it is generally necessary to use a magnifying glass to analyze the original color samples and eliminate diluting agents. After the main color, it is necessary to pay attention to the color deviation of the ink, which is generally adopted by gradually adding a primary color ink to the diluting agent.
Light-colored ink is generally made up of diluting agent or white ink plus original ink. It is necessary to pay attention to the deployment of light ink based on white ink. Its color powder, ink is fresher, and it has strong hiding power. Because the white ink pigments are easy to be plated, the blankets are piled, and the light resistance is not good, and it is suitable for the monochrome printing of the actual printing field, and is generally a pink-blue pink column spot color ink. Diluted light-based light-colored ink has a certain degree of transparency, does not have hiding power, color is not fresh, suitable for multi-color overlapping printing, usually light red, light yellow, light gray and other series of spot color ink.
In summary, the deployment of spot color inks, because it involves the theory of light color, ink, paper, technology, etc., make the spot color ink deployment more difficult, and is currently mainly based on experience, so the requirements of the ink transfer personnel Higher, first to master the theory of light color, followed by the need to master the properties of commonly used ink, etc., have a keen, accurate ability to identify colors, and continue to consciously practice their own application ability through practice, that is to see a In hue, you can quickly report the ink ratio. Only in this way can we quickly and accurately match spot color inks to provide better quality services and improve product quality. ("Printing Resources")