Shanghai Fancai: аспекты качества цвета печати этикеток, на которые следует обратить внимание

[ppzhan abstract] In the field of label printing, the accuracy of color reproduction is an important factor in evaluating product quality. Moreover, a particularly large variety of spot colors is used in label printing, and the types of substrates are also quite diverse. The color evaluation methods commonly used today include: visual evaluation (subjective perception), upper and lower limit judgment (subjective perception), and spectrophotometer tolerance evaluation (data).

Based on many years of experience in color inspection and color management, combined with the actual production conditions of a number of label printing companies, we have summarized the following aspects that require special attention in color quality control for label printing:

1. Clarify the color standard and upper and lower limits of the product, that is, the product color standard and tolerance. When we produce a certain label product, we can set the upper limit, standard and lower limit of the product, and seal and keep the standard sample confirmed by the customer. However, after a long time, the sealed sample will change color, so it is necessary to use an x-rite spectrophotometer together with related quality control software to properly save the standard measurement data and tolerance data under common measurement conditions. In later production, operators and quality inspectors can produce and inspect according to this standard and tolerance. This not only ensures the consistency of label color, but also provides a certain fluctuation range for actual production, making it operable.
2. Control of color consistency in prepress and plate-making. For some products that need to match a sample, since the dot size and density on the printing plate cannot be exactly the same as the sample provided by the customer, color differences will appear in color reproduction. Therefore, while maintaining the consistency of prepress electronic data, we also need to maintain the consistency of plate dot data. This is especially true for flexographic printing and gravure printing. We measure the data of each plate, including the screen line count, screen angle and density of the plate. For flexographic labels, we can use the FAG flexo plate measuring instrument to carry out 3D data evaluation and measurement of the plate data. For letterpress and offset label printing, we can choose the x-riteicplate2XT plate inspection instrument to measure the plate data. In this way we can ensure consistency in color quality control in repeat orders.
3. The importance of a standard light source environment for color quality control. At present, many label printing companies do not use standard lighting sources, which creates a hidden risk for controlling the color consistency of label prints. Many printing companies run two or three shifts, which means that the colors seen by the day shift and the night shift under the lighting source differ greatly from those seen under daylight, thus leading to printing color differences. Therefore, it is recommended that, where conditions permit, label printing companies be equipped with a standard light booth or a standard light source viewing table, so that employees can compare colors in a unified viewing environment. This can effectively avoid color difference problems in label prints caused by light source issues.
4. Consistency control of spot color inks. Because many spot colors are involved in label printing, and because spot color inks prepared according to the proportions on the Pantone color card are not accurate enough, there is often an obvious color difference between the ink system actually used and the Pantone base color inks. Some factories do not use a Pantone base color ink system at all. Based on the current development of relevant color matching technology and actual production applications, we recommend using a computer color matching system, appropriately combined with the experience of color matching personnel, to make spot color ink matching faster, more accurate and more controllable. The system can also allow users to conveniently and easily store and manage a large database of spot color ink formulas, making it easy to retrieve and use them in a timely manner.
5. In flexographic label printing, the effect of the screen ruling and screen type of the anilox roller and the depth of its cells on label color consistency. More and more labels are now printed by flexography. Sometimes, when matching the sample color provided by the customer, even if the prepress files, printing plates and spot color inks are all kept consistent with before, differences in spot color hue still appear on the label. This may be caused by wear of the anilox roller. Generally speaking, in flexographic printing, the ratio of the screen ruling of the anilox roller to that of the printing plate is 3:1 or 4:1. Therefore, when using flexographic printing for labels, in addition to checking the screen ruling and dots of the plate, one must also check the screen ruling and screen type of the anilox roller and the depth of its cells. Pay special attention to the fact that process differences between metal anilox rollers and ceramic anilox rollers will also cause color differences in label printing.

Regarding the several key points above that affect color reproduction in label printing, Shanghai Fancai has already provided mature solutions to some companies in the industry. These have played a very positive role in improving the operability of color control for label printing companies, reducing cost waste and increasing production efficiency, and have won recognition from a group of label printing companies represented by Zhengwei.

With the development and progress of science and technology, printed labels will show a development trend of environmental friendliness, personalization, functionality and scale, and the innovation of digital printing will surely lead the future of label printing. Digital printing has several major characteristics: a simple process and saved plate-making time; on-demand printing, which can reduce inventory; variable data with obvious personalization; suitability for short runs, effectively reducing the printing cost of short runs; and it can better guarantee the high quality of label printing.

——This article is reprinted from China Packaging Network (pack.cn). Original link: http://news.pack.cn/show-361787.html