Ink preparation

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Most of the current prints are printed on the basis of four-color inks, but we often encounter some prints with special requirements in the printing process, which require spot color inks. Sometimes spot color inks can be printed by direct purchase, sometimes due to cost or special ink color requirements need to be obtained by mixing primary color inks.
Generally speaking, there are two main ways to formulate ink, one is to rely on the ratio of the chromatogram to prepare; the other is to rely on the color density agent to measure, based on the obtained value for the preparation; the other is the more commonly used The operators (some of the larger printing plants are specially assigned to adjust the ink) rely on experience to directly deploy. This last one is the method we often use. The following article discusses some of the methods and experience of this ink formulation.

1. Analyze the color of the manuscript or print. Before you start to prepare the ink, you should first analyze the manuscript or the printed sample in detail.
If there is a color sample as it is, you can refer to the color of the monochrome sample when mixing the ink. If the original does not have a single color print, you can find a place on the print that can represent the color as a reference. You can find an appropriate part of the printed part that has the dots of that color, but where there is less overlap of the dots, use a magnifying glass to observe. But at this time, you should pay attention to observe the relationship between the ink color and the surrounding color. If you let yellow and red go side by side, you will find that yellow tends to be red and purple. Similarly, for the same number of yellow inks, it is not light when printed directly on white paper. If blue or black is printed around, it will appear light and bright. These deviations will directly affect our ink selection. Work, therefore, the surrounding colors should be covered when distinguishing colors, and a single observation will not cause the illusion of color deviation.
When analyzing the hue, the principle of "color subtractive color method" can be used to consider, that is, to analyze the content of the original sample in the three primary colors with the theory of the three primary colors, and determine the proportion of the primary color and the secondary color. Generally speaking, a primary color ink is the main color, and the other is the secondary color. For example: configure green ink, then mix yellow and blue. If the green is inclined to yellow, it is mainly yellow when configuring, and the blue is supplementary, but before configuring, it is necessary to consider which yellow ink and blue ink are applied to better match the hue. If dark blue and dark yellow are used, the green ink will have a red hue, and the color will be dark and not bright. If you use light yellow and hole blue or medium blue to mix, you can get a fresher green ink hue that tends to yellow.
In theory, the three primary colors are added in equal proportions to get black, but the blackness of the three primary colors of the printing ink is often not enough. When the color matching requires gray tone, in addition to the black ink directly, sometimes add some blue light .
The analysis of prints is equally important, and often makes it difficult for beginners. In order to make the correctness of the hue faster, we must have the following knowledge before adjusting the ink:
1. Have a certain understanding of the basic changes in color;
2. Chromatography can be prepared as a reference, because the composition of the chromatography and the composition of the ink are basically the same;
3. To have a certain perceptual understanding of the color of the ink, and a sufficient understanding of the color deviation of the ink.

Second, the allocation method After the analysis of the color of the print is completed, we can design a formula, determine the number of the main color ink and the auxiliary color ink, and roughly calculate the ratio of the main ink and the auxiliary ink, and then can be adjusted in proportion .
a) The preparation of dark ink is only used for the preparation of primary ink, without adding any diluent, which is collectively called the preparation of dark ink. Weigh the ink used in advance, put the primary color ink into the ink tray, and then gradually add the secondary color ink. After reconciling, two small pieces of paper (generally coated paper is ideal) can be used. The ink is made into small color samples, and see if the hue meets the requirements. If the eyes are unrecognizable, use a magnifying glass to compare it with the original. The hue generally configured can be slightly darker than the original color, so that the color of the ink can be as it is after printing and drying after printing.
If, during the configuration process, the dosage according to the envisaged formula fails to meet the original requirements, additional auxiliary materials need to be added. At this time, the dosage of the added materials should be recorded in detail until the hue matches the original.
According to the theory of subtractive color method, the number of primary color inks should be used as little as possible when mixing inks, otherwise the brightness of inks and the vividness of colors should be reduced.
b) The preparation of light-colored inks The inks prepared by adding diluent are collectively called light-colored inks. The preparation method should never add diluent to the original ink to prepare. Because the primary color ink has a strong color developing ability in the diluent, and the coloring capabilities of the primary color inks are different, the general rule is black> red> blue> yellow, so it is easy to cause inaccurate hue and waste ink. Generally, the primary color ink is gradually added to the diluent to prepare, and most of them are adjusted in small amounts. After the hue meets the requirements, the amount of ink consumed for the deployment of the printing is expanded in proportion.
The content of primary color ink in the diluent is generally settled with the remaining amount. For example, black ink is used to prepare light gray. The pre-hue analysis is 10: 3. Weigh three or two black inks aside and gradually add them to a pound of diluent. After the hue meets the requirements, weigh the remaining ink. If the weight is five cents, the ratio of diluent to black ink in the gray ink is 100: 25 or 4: 1.
For the allocation of general light-colored ink, you can refer to the following coordination relationships:
Light red: mainly white ink, slightly increased red and orange.
Light (lake) blue: mainly white ink, slightly peacock blue. If the hue is darker, you can add medium blue or magenta.
Jade (flesh) color: mainly white ink, slightly orange, yellow.
Beige: mainly white ink, slightly orange, yellow and trace black.
Gray: Mainly black ink, slightly black ink and magenta. The hue is dark and light, and blue primary ink can be used to adjust its color cast.
Silver gray: mainly white ink, with a little silver paste and a little black ink.
Light snow green: mainly white ink, light red and magenta.
Ivory yellow: mainly white ink, with medium yellow, peacock blue and orange red.

Third, the identification of the hue when preparing the ink How to identify the difference between the hue of the prepared ink and the original hue, usually by the method of color contrast:
a) Ink method: This is a more common method. On the printing paper, take a piece of ink with a size like a bean, and use your fingers (or line a layer of printing paper) to spread this small piece of ink into a piece It is basically close to the printed uniform ink layer, and then compare it with the original color sample, and observe the difference in hue from the color sample. According to the difference, add the color cast ink until it matches the original color sample. If the ink layer is too thick or too thin, it will cause the illusion of color contrast. The paper used for extension must be the paper used for the printed matter. Any rubbing on the multi-color ink should be rubbed on the first color printed. The color of the ink can be darker than the original one during the extension. This is due to the lack of printing pressure, and its ink layer is always more vague. When printing, the pressure on the paper is very large, the ink layer is strong and even, and the actual ink volume is always smaller than the extension. The thin ink layer results in poor coloring power.
b) Scraping method: The scraping operation is also very simple. On the top of the vertical rectangular paper, use a large ink knife to use two inks that need to be compared (usually one of them is a trial ink that matches the original color sample) Apply a little bit to the surface of the paper, then use a scraper (ink knife) to scrape the ink from top to bottom into a thin layer, and make the two inks form a straight shape at the place of contact for easy comparison Boundary.
After scraping the ink sample, observe with eyes and compare the difference between the two. Then correct according to the color difference.
Regardless of whether it is the ink method or the scraping method to compare and distinguish colors, it is visually observed. Not only is it affected by the environment, but also the color discrimination of each person is not very consistent, and the error is often large. Sometimes the hue of the ink needs to be adjusted before the machine starts printing. Of course this is trace.

Fourth, the determination of the amount of ink deployment.
Due to the wide variety of offset printing, uneven pattern distribution, and different product requirements, some products that absorb a lot of ink consume a few kilograms of ink per paper, and only a few dozen grams of ink, so the amount of ink consumption varies. Very large, it is difficult to have accurate figures. Generally, it can only be estimated based on experience accumulation. Ordinary folio advertising posters can print about 1,000 to 2,000 sheets per pound of yellow ink. A pound of red and blue can print about 2000-3000 sheets, a pound of black ink can print about 3000-5000 sheets. The above figures are for reference only. Before adjusting the ink, you should decide the amount of mixing according to the specific conditions of the product and decide that you can't just move it.
The factors that determine the amount of ink blended include: the number of prints and the number of openings of the paper, the strength of the paper's ability to absorb ink, and the coloring power of the ink. Excessive use of printed ink will cause waste; if too little is used, it will take time to re-adjust. Once the ink color is more complicated, it is difficult to reconcile the second time, which will affect the quality of the printed product. The amount of ink to be prepared before printing is slightly more than the actual application, and a record of the ink to be prepared should be made for future checks and conclusions.

5. Problems to be paid attention to in the ink preparation.
a) Before distributing ink, the basic hue of the original or printed sample should be analyzed accurately to determine the main and auxiliary colors and the color matching ratio.
b) When coloring, the main color (light color is white) should be the main color, and the auxiliary color ink should be added gradually. Beginners should first configure a small amount, and then increase the amount of ink in proportion.
c) The amount of ink distribution should be slightly larger than the amount of ink used for printing to avoid inconsistencies in the hue of the printed product caused by secondary ink distribution.
d) The golden red ink should not be diluted or used with orange ink to prevent fading.
e) When using quick-drying bright ink to adjust the light color ink for matching colors, such as light red, light blue, etc., the corresponding quick-drying (removal) light agent (such as 05-93) or bright paste (such as 05) should be used -90), to ensure the gloss and dryness of printed products.
f) For the light-colored ink used on ordinary printed products, it can be diluted with transparent oil or Veli oil. However, the ink diluted with transparent oil has poor print gloss, which has a certain effect on the drying property. It should be noted that the dry oil is added and used with it. It should not be left for a long time (long time will thicken).
g) For light-colored inks used on general printing products with lower requirements, white oil can be used to dilute, or white oil and transparent oil can be used together to dilute.
h) No matter what kind of adjuvant is used, you should first be familiar with its performance and avoid blindly adding it; the dosage should be less, and too much will cause other ills.

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