1. Light-colored inks can be divided into three types:
① Dilution ink mainly based on dissolving agent: it has certain transparency and is suitable for multi-color overprinting of ink.
② Matting ink based on white ink: It has strong hiding power and bright ink color. Generally, light-colored inks for synthetic paper are adjusted with white ink.
③ Light-colored ink mixed with diluent and white ink.

2. Spot color ink preparation method
① Proportional method
Ink color matching, we must first carefully observe and analyze the ink samples or printing samples. The ink sample can be a wiper sample on Dowling paper, or the print sample can be printed with a printing suitability meter. Generally, the ink volume of the four-stage roller is 0.1m, and the ink volume of the two-stage roller is 0.15ml. First, observe and analyze which colors of ink the printed sample may consist of. Use a copper suction tube with a scale to roughly adjust the proportion. Look at the rough adjustment of the ink sample (squeegee) and the standard sample, and record the ink ratio and ink volume. If it is close, convert the proportional number to a percentage, and then use the analytical balance to fine-tune it; if it is not close, you should change the proportion of the famous color ink and continue to allocate.
② Reduction method
After determining the standard sample (standard color sample provided by the customer or an ink sample that is not close to the standard sample), which color inks are composed, find out the contained ink, and place it on a glass plate with 10g or 5g of sulfuric acid paper name. Take out the ink used, when the ink color is close to the standard sample, you can use a little ink sample scraper, observe the surface color, background color, and the ink used when scraping the film to be recovered. If it is close to the standard sample, weigh the remaining ink to convert the percentage content of the spot color ink. Then use the balance to fine-tune, if it is near the standard sample, continue to adjust.
③PANTONE color matching method
The PANNTONE Formula Guide 2000 version of the Pantome color matching guide contains 1114 Pantome spot colors, which is a universal color guide in the world. Each color standard provided by it has a number and an ink adjustment ratio. It uses fan binding and color selection. fast and convenient. For Pantome spot color inks, you must carefully observe and analyze the printed samples, compare with the color samples of the Pantome Color Matching Guide to find the close color samples, and if they are very close, write down the color serial number and compare the printed samples of the TCT ink color matching guide. , Analyze whether the printed samples of the two color matching guides are consistent; if there is an error, find out which matching ink is caused by the error. After analysis, the proportion of the printing ink can be adjusted. This can make deployment easier.

3. The main points of spot color ink deployment
Operation process of blending spot color ink. Pay attention to the following points when preparing the ink.
① Take into account the characteristics of post-press processing: When selecting the ink, it is necessary to consider the post-print processing conditions. For example, the printed product needs to be glazed, then the general ink can be selected. Gloss effect.
② Blending of the same type: The mixing of inks should be based on the same type of mixing as much as possible. For example, when mixing intermediate colors and multi-colors, if there is no offset printing fast-drying ink, you can use offset printing resin ink instead, but pay attention to the mixing ratio If there are too many offset printing resin inks, it will affect the characteristics of offset printing fast-drying inks, which will not achieve the purpose of improving print quality. The knowledge of ink color tells us that the more varieties of ink mix, the darker the color. Therefore, those who can use the primary ink do not use magenta ink; those who can use magenta ink do not use multicolor ink.
③Determining the basic ink: If the color of the printed sample requires more than two inks, you must determine which color is used as the basic ink and gradually add other inks; for example, use light-colored ink as the basic ink and gradually add dark ink. In this way, the ink volume will not be too much.
④ The density of the printed samples is the same: when the color is adjusted according to the printed samples, the ink volume of the adjusted ink samples should be adjusted when printing, so that it is consistent with the density of the printed samples.
⑤ Pay attention to recording and calculation: Especially when adjusting spot color ink according to the proportional method, it is necessary to record the amount of ink added and the amount of ink remaining at any time, which is conducive to calculating the final ratio.
⑥ Adjusting ink properties: In the deployment of spot color inks, in addition to color matching, a certain amount of auxiliary agent is sometimes added to change the ink properties to meet customer needs.
⑦Pay attention to printing methods and characteristics: When mixing ink colors, you should consider the printing methods and characteristics, and clearly determine which printing method the oil is used for, such as letterpress or lithographic printing, printing on the field or printing screen. Because the thickness of the ink layer formed by different printing methods is different, the color is also different. For example: For inks that are mainly printed with screen lines, they can focus on the same background color when they are color-matched; if they are based on the ground, they can focus on the same color when they are color-matched; if they are both, the background color and the surface color We have to take into account.
⑧Paper Consistency: The paper used for spot inks must be consistent with the printing paper to avoid color errors caused by different papers.
⑨Consistent printing time: When the customer provides the ink sample as the standard sample to match the spot color, the standard sample and the sample must be printed at the same time, so that the color difference between them can be accurately judged.
准确 Accurate weighing: After finding the initial mix ratio, you must use the balance to fine-tune the balance to ensure the same color for the small sample (5g), enlarged sample (100-2000g), and production sample. And pay attention to mixing well.
Spot color inks generally require higher color accuracy. Whether it is qualified or not is not based on the approval of the deployment staff, but based on the customer's satisfaction after the enlarged sample is printed in the printing factory, or Confirm with color measuring instrument.

4. Application of spot color ink
① What kind of products will be printed with spot color inks?
The cover of packaging products or books and magazines is often composed of uniform blocks of different colors or regular gradient blocks and text. These color blocks and text can be overprinted with four primary color inks after color separation, and spot color inks can also be deployed. , And then print only one spot color ink at the same color block. Under the comprehensive consideration of improving the printing quality and saving the number of overprints, spot color printing is sometimes used.
② What is the difference between the visual effect of the spot color printing block and the four-color overprinting color block?
The inks formulated by spot-color printing are obtained in accordance with the principle of subtractive color mixing method. The color brightness is low and the saturation is high: spot inks with uniform ink colors are usually printed in the field, and the ink volume should be appropriately increased. When the thickness of the ink layer on the layout is large, the sensitivity of the change in the thickness of the ink layer to color changes will be reduced, so it is easier to obtain a uniform ink color and a thick printing effect.

The color blocks printed by the four-color printing set are mostly composed of a certain percentage of the dots. When printing the dots, the thickness of the ink layer must be strictly controlled, and it is easy to change the thickness of the ink layer and print. Changes in process conditions cause changes in color intensity. Changes in the degree of network expansion. As a result, the color changes. And because any change in the color of the color block will result in a change in the color of the color block, the chance of uneven ink color will be multiplied. Therefore, the color block overprinted by the four-color printing process is not easy to obtain. Even effect. If you cannot use a multi-color machine to overprint the color of the color block at a time. It is also prone to color misregistration because the color of the semi-finished product is not easy to control. In addition, the four-color printing has the combined effect of subtractive color absorption and additive color method of halftone dots. The color block has higher brightness and lower saturation. For light-colored patches, a four-color printing process is used. Due to the low coverage of the ink on the paper, the ink is dull and lacks a thick feel. Due to the angle of the dots, it is inevitable that people will feel the existence of patterns.
③ From the perspective of improving product quality, what kind of products are suitable for spot color printing?
When printing a large area of light-colored uniform color patches, it is usually added to the original ink to mix the spot color ink and then printed on the spot. This way, the ink layer is thicker, and it is easier to obtain uniform and thick colors. If a four-color printing process is used, a low percentage of flat screen dots must be used. However, the low-numbered flat screen dots are easy to be caused by small sand particles or slightly poor air extraction, resulting in smaller dots in individual parts, leading to uneven ink color: it is easy to over-water supply due to the layout when printing. Paper powder accumulates on printing plates and blankets, and low smoothness of the paper causes poor ink transfer at small dots. As a result, the ink color becomes lighter and the ink color becomes uneven.
For dark and large-area color blocks, the four-color printing process may be used. It may need to be superimposed with high-salinity dots of several colors. The ink layer is too thick and prone to dirty on the back. With the spot-color printing process, only one Color, easy to appear dirty on the back. Using four-color printing process, some parts of the graphic may be composed of several colors; while using spot-color printing process, the corresponding part is printed with only one color, which avoids the possibility of overprinting errors.
④ From the perspective of economic benefits, what kind of products are suitable for printing with spot colors?
From the perspective of economic benefits, it mainly depends on whether the use of spot color printing technology can save the number of overprints. Because reducing the number of overprints can save both printing costs and pre-press production costs.