Ink mixing
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Most of the current prints are based on four-color inks, but we often encounter prints with special requirements during the printing process, which require the use of spot inks. Sometimes spot color inks can be printed by direct purchase, sometimes from the original color inks for cost or special ink color requirements.
In general, there are two main ways to blend inks. One is based on the ratio on the chromatogram; the other is based on the color density agent, which is based on the numerical value. The other is the more commonly used machine. The operators (some of the larger printers are specializing in ink adjustment) rely on experience to directly deploy. This last one is the way we often use it. The following article discusses some of the ways and experience of this ink formulation.
First, analyze the original or print color
Before the ink is dispensed, the original or the printed sample should be analyzed in detail.
If the color sample is left as it is, it can be referred to the monochrome ink color when the ink is dispensed. If the original does not have a monochrome print, you can find a place on the print that can represent the color as a reference. For printing, you can find a suitable part that has the color dot, but where the dot overlap is small, use a magnifying glass to observe. However, you should pay attention to the relationship between the ink color and the surrounding color. If you let yellow and red juxtapose, you will find that yellow tends to be reddish purple. Similarly, for the same number of yellow inks, it is not light on the white paper. If it is printed with blue or black around, it will appear light and bright. These deviations will directly affect our ink selection. Work, therefore, in the color discrimination should cover the surrounding color, a single observation, will not cause the illusion of color shift.
In the analysis of hue, the principle of "color subtraction method" can be used to consider, that is, the content of the original color in the three primary colors is analyzed by the three primary color theory, and the matching ratio of the primary color and the secondary color is determined. Generally speaking, one primary color ink is the main color, and the other is the secondary color. For example, if you configure a green ink, mix it with yellow and blue. If the green color is yellow, the configuration is yellow, and the blue color is auxiliary. However, it is better to consider which yellow ink and blue ink are used to match the hue before the configuration. If you use dark blue and dark yellow, the green ink will have a red color, and the color will be dark and not bright. If it is formulated with light yellow and hole blue or medium blue, you can get a more vivid green ink hue that tends to yellow.
In theory, the three primary colors are added in equal proportions to get black, but the three primary colors of the printing ink are often not enough. When gray color is needed for color matching, in addition to directly applying black ink, sometimes some light blue is added. .
The analysis of the prints is equally important, and often makes it difficult for beginners. In order to make the color correctness 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 used as a reference, because the composition of the chromatogram and the composition of the ink are basically the same;
3. To have a certain perceptual understanding of the color of the ink, and to have a sufficient understanding of the color shift of the ink.
Second, the deployment method
After completing the analysis of the color of the print, we can design a formula to determine the number of the primary and secondary inks, and roughly calculate the ratio of the primary and secondary inks, which can then be scaled.
a) Dark ink blending
Only use the original color of the ink, without adding any thinner, collectively referred to as the dark ink blending. Pre-weigh the ink used during the preparation, put the main color ink into the ink tray, and then gradually add the auxiliary color ink. After the adjustment is even, two small pieces of paper can be used (usually ideal for coated paper), and a very small amount is taken. The ink is made into a small color sample to see if its hue meets the requirements. If the eye is unrecognizable, use a magnifying glass to make it as it is. Generally, the hue can be slightly deeper than the original color, so that the ink can be used as it is after the action of the syrup and drying after printing.
If, during the configuration process, the amount of the formula is not as expected, additional auxiliary materials need to be added. In this case, the amount of the added materials should be recorded in detail until the hue is the same.
According to the theory of subtractive color method, the number of primary color inks should be used as little as possible when formulating inks, otherwise the brightness of the inks and the color of the colors should be reduced.
b) blending of light inks
The inks formulated by adding a thinner are collectively referred to as light inks. The method of blending must not be added to the original ink to add a thinner. Because the primary color ink has strong color-developing ability in the thinner, and the coloring ability of each primary color ink is different, the general rule is black>red>blue>yellow, so it is easy to cause hue inaccuracy and waste ink. Generally, the primary color ink is gradually added to the thinner to be blended, and most of them are firstly adjusted in a small amount. After the hue meets the requirements, the amount of ink used for printing is expanded proportionally.
The content of the primary color ink in the thinner is generally settled by the remaining amount. For example, black ink is used to blend light gray. The pre-dye analysis is 10:3. First, the two black inks are placed on one side, and gradually added to one pound of the thinner. After the hue reaches the requirement, the remaining ink is called. If it is five yuan, the ratio of the thinner to the black ink in the gray ink is 100:25 or 4:1.
For the deployment of light inks, you can refer to the following combinations:
Light red: mainly white ink, slightly increased red, orange red.
Light (lake) blue: mainly white ink, slightly added peacock blue. If the color is darker, you can add medium blue or royal blue.
Jade (meat) color: mainly white ink, slightly orange, medium yellow.
Beige: Mainly white ink, slightly orange, medium yellow and trace black.
Gray: Mainly black ink, slightly black ink, royal blue. The hue is dark, and the color cast can be adjusted with the blue primary ink.
Silver gray: mainly white ink, slightly silver paste, a small amount of black ink.
Light snow blue: mainly white ink, slightly reddish, royal blue.
Ivory yellow: mainly white ink, plus medium yellow, peacock blue and orange red.
Third, the identification of hue when dispensing ink
How to identify the difference between the hue of the formulated ink and the hue of the original, usually by color contrast:
a) Ink method: This is a more common method. On the printing paper, take a piece of ink that is sized like a bean, and use a finger (or a layer of printing paper) to spread the piece of ink into a piece. It is basically close to the printed uniform ink layer, and then it is compared with the original color sample to observe the difference in hue from the color sample. According to the difference, add the color cast ink until it matches the original color. The ink layer of the extension is too thick or too thin to create an illusion of color contrast. The paper used for the extension must be the paper for the print. Any extension on the stacked ink will be spread on the first color that has been printed. The color of the ink can be deeper than it is when the sample is expanded. This is because there is no pressure to print, and its ink layer is always more vain. In the printing, the pressure on the paper is great, the ink layer is firm and uniform, and the actual ink volume is always smaller than the topography. The ink layer is thin and the tinting strength is poor.
b) Scratch method: The scraping operation is also very simple. On the upper part of the vertical rectangular paper, use two large ink knives to use two kinds of inks to be compared (usually one of which is the test ink that matches the original color sample). Drip on the paper, a little closer to the point, 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 in the contact area, easy to compare The line of demarcation.
After the ink sample is scraped, it is observed by the eye and the difference between the two is compared. Then correct according to the chromatic aberration.
Whether it is the ink method or the scraping method to compare and identify the color, it is based on the observation of the eyes, not only by the influence of the environment, but also the color of each person is not very consistent, often the error is relatively large. Sometimes it is often necessary to adjust the hue of the ink before the machine starts printing. Of course this is a trace amount.
Fourth, the determination of the number of inks.
Due to the wide variety of offset printing, the pattern distribution is different, the product requirements are different, some products with a large amount of ink absorption, a paper will consume a few pounds of ink, and even less than a few dozen grams, so the ink consumption is different. Very large, it is difficult to have accurate numbers. Generally, it can only be estimated by experience accumulation. Ordinary open advertising posters, a pound of yellow ink can be printed about 1000 to 2000. A pound of red and blue can print about 2,000 to 3,000 pieces, and a pound of black ink can be printed about 3,000 to 5,000 pieces. The above figures are for reference only. Before adjusting the ink, it is necessary to adjust the quantity according to the specific conditions of the product, and decide not to move the hard cover.
The factors that determine the amount of ink to be dispensed are: the amount of printing and the number of sheets of paper, the strength of the ink absorption of the paper, and the tinting strength of the ink. If the ink is too much to be used, it will cause waste. If it is too little, it will take time to re-distribute. Once the ink is more complicated, the secondary deployment is difficult to be consistent, which will affect the quality of the printed matter. The amount of ink dispensed before printing should be slightly more than the actual application amount, and the record of the formulated ink should be prepared for later check and summarize the experience.
Fifth, Problems to be aware of in ink blending.
a) Before the ink is dispensed, the basic hue of the original or the print should be analyzed accurately to determine the primary and secondary colors and the color ratio.
b) The main color (light color is white) should be used for coloring, and the auxiliary color ink should be gradually added. Beginners should configure a small amount and then increase the amount of ink proportionally.
c) The amount of ink to be dispensed 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) Golden light red ink should not be diluted or used with orange ink to prevent fading.
e) Use light-drying ink to adjust the color of the matching color, such as light red, light blue, etc., should use the corresponding quick-drying (extract) light agent (such as: 05-93) or bright light paste (such as 05 -90) to ensure the gloss and dryness of the printed product.
f) For the light color ink used on ordinary printing products, it can be diluted with transparent oil or oil. However, the ink diluted with transparent oil has poor gloss, which has a certain influence on the drying property. It should be added to the dry oil and used with it, and it should not be placed for a long time (it will become thicker after a long time).
g) For the light-colored ink used on the general printed products with lower requirements, use white oil to dilute, or use white oil and transparent oil to dilute.
h) No matter what kind of adjuvant is used, you should first familiarize yourself with its performance, and should not blindly add it; use less in the dosage, too much will cause other ills.
Sixth, the amount of additives added when the ink is formulated, the attached table:
Main use of the product
Liquidity adjustment: Dry vegetable oil ↑ viscosity, ↓ fluidity 1 to 5%
No. 6 oil Petroleum fraction ↑ viscosity, ↓ fluidity 1 to 5%
Thinner Resin, dry vegetable oil, mineral oil Does not affect fixation
Resin varnish ↑liquidity, slightly reduced viscosity 3 to 10%
Sticky adjustment:
Detachment Aluminum stearate, Reduce stickiness and keep it sticky 3 to 5% dry oil petroleum solvent
Concentration adjustment:
Detachment Resin, dry oil, mineral oil, Resin ink concentration adjustment base on needs
Wei Li oil aluminum compound, wax Mainly for oil type ink concentration base on needs
Al(OH) 3 adjustment