[China Packaging Network News] At present, color matching methods for spot color inks are mainly divided into traditional spot color inks and computer spot color inks. Based on the summary of the research experience of offset color ink ink color matching technology, the author puts forward some suggestions for spot color ink color matching technology for peer reference.
Traditional spot color ink color matching method
The traditional spot color ink color matching method is based on the skill and experience of operators for many years, and color matching through observation and comparison, and is generally applicable to small package printing companies with lower color requirements. However, in the course of use, many companies have reported that, even if the color matching method is used properly, the color difference between the printed product and the original document is still large, and the defective product rate is high, which seriously affects normal production.
It is understood that when comparing the spot colors configured with the traditional spot color ink color matching method with the original spot colors, the general practice is to first manually apply the ink and then compare it with the original spot color. In fact, this practice is unscientific. Because the uniformity and thickness of the ink layer affect the color effect of the spot color ink to a large extent, when the color of the ink after the ink is not much different from the color of the original, the operator will mistakenly believe that the spot color ink has been prepared. As a result of the printing, the color difference between the print and the original is very far away. In this process, the traditional spot color matching method is combined with the mechanical ink distribution mechanism, so that the color difference of the printed product caused by the misjudgment of the head judge can be reduced.
In addition, the effect of paper on the color matching effect of traditional spot color inks cannot be ignored. Different materials of paper have different effects on the color of printed materials. In the process of pattern making and comparing with the original, the same paper as the printed material is required.
Even if it is improved, there may still be metamerism due to the use of color, which means that two color printing samples look the same under one light source, but they show differences under another light source. Therefore, Hengsong suggested that, as far as conditions permit, try to use computer spot color ink color matching
Computer spot color ink color matching method
For large-scale packaging and printing companies with high color requirements, computer spot color ink color matching methods are commonly used in color matching. The principle is to first use the spectrophotometer to measure the target color. After being processed by the computer color matching software, the color information of the target color is expressed in the form of objective data, and then the color data stored in the database is used for color matching and can be formulated by calculation. Spot color ink formulation that is close to the target color hue. When the color difference between the reproduction color and the target color due to the influence of factors such as raw material properties and process parameters, the computer color matching system will automatically correct the used formula and control the color difference within the allowable range.
In order to restore the color of spot colors more efficiently and accurately, it is necessary to optimize computer color ink color matching technology and pay attention to the following points:
(1) The primary color sampling must be accurate, otherwise it will directly affect the color matching effect. Therefore, when establishing the basic color standard, it must be strict and meticulous, and try to eliminate all external factors.
(2) Ensure stable ink transfer. A number of experiments have found that if ink printing is used directly to print color samples, the ink thickness and uniformity on the color samples cannot meet the higher color requirements of large-scale packaging and printing companies. This is mainly because the ink is too thick and has poor flowability. As a result, the ink transferability is reduced and the color difference is large, thereby affecting the accuracy of the primary color sampling. The ink must be placed in an oven with a temperature of 100°C and cooled for half an hour before the sample is produced. This greatly increases the fluidity of the ink and allows better ink transfer. In addition, the ink must be accurately and cleanly weighed to avoid the ink floating color, hair and other phenomena caused by the ink transfer.
(3) The substrate must be selected from the substrate. After a portion of the substrate is determined, its relevant performance parameters are stored in the computer, and another part of the substrate is used to make the primary color sample.
(4) General principles and precautions for sample preparation: The sample must be made by the same person and the methods must be the same; the ink used to make a set of primary color samples must be weighed out at one time; the production conditions for the primary color samples should be simulated as far as possible. The conditions, the type, amount, time, temperature and post-treatment conditions of the auxiliary agent must also be similar to the production conditions.
(5) Try to use the least kind of ink for color matching, because the less the type of ink, the better the saturation of the mixing effect and ink color.
(6) Select the same manufacturer or the same series of inks as much as possible during the color matching process. Otherwise, color unevenness will occur. In severe cases, the ink will coagulate and be scrapped.
(7) Make sure the rollers of the IGT proofer are clean and clean. This has a great influence on the accuracy of the sample. When measuring the sample data, three test points at different positions on the same sample can be measured separately. Finally, the average value is taken.