Shanghai Fancai: Color Quality Control for Label Printing

In the field of label printing, the accuracy of color reproduction is an important factor in product quality evaluation. In addition, the types of spot colors used in label printing are particularly large, and the types of printing materials are also quite diverse. At the same time, they also involve cold rolling, blanching, glazing, and sometimes even a combination of printing methods. These factors have an impact on the accuracy of spot color reproduction. The commonly used color evaluation methods are: human eye evaluation method (subjective feelings), upper and lower limit determination methods (subjective feelings), and spectrometer tolerance evaluation (data).

Based on years of experience in color detection and color management, combined with the actual production status of a number of label printing companies, we summarize the following aspects of color quality control for label printing that require special attention:

1, clear product color standards and upper and lower limits, that is, product color standards and tolerances. When we first produce a label product, we can formulate the product's upper limit, the standard and the lower limit, and seal the sample that the customer has confirmed. However, after a long time, the color change of the seal will occur. Therefore, it is necessary to use an x-rite spectrometer and relevant quality control software in combination to save the standard measurement data and tolerance data under the general measurement conditions. In the later production process, operators and quality inspectors can perform production and inspection according to this standard and tolerance. This will not only ensure the consistency of the color of the label, but also provide a certain range of fluctuations to the actual production, with operability.

2. Color consistency control in prepress and platemaking processes. For some products to be sampled, because the dot size and density on the printing plate cannot be completely consistent with the samples provided by the customer, this will cause the color difference in the color reproduction to occur. Therefore, under the premise of maintaining the consistency of pre-printed electronic data, we still need to maintain the consistency of the printing plate outlet data. Especially when flexo and gravure. We conduct data measurements on each plate, including the screen's cable, screen angle, and density. In the flexo label we can use the FAG flexometer to perform 3D data evaluation and measurement of the plate data. In the embossing and lithographic offset labels, we can choose to measure the plate data using the x-rite icplate2XT plate detector. In this way we can guarantee the consistency of color quality control in repeat orders.

3, standard light source environment for the importance of color quality control. At present, many label printing companies do not use standard lighting sources, which poses a certain hidden danger for the control of the color consistency of label prints. Many printing companies implement shifts of two or three shifts. This causes the daylight and night shifts to see different colors under the light source and daytime sunlight, resulting in the production of color differences. Therefore, it is recommended that label printing companies should configure standard light source boxes or standard light sources to see the sample platform under the conditions permitting, so that employees can perform color comparisons in a uniform viewing environment. This can effectively avoid the problem of chromatic aberration of labels due to light source problems. .

4, spot color ink consistency control. Because the spot colors involved in the label printing are many, and the spot color inks prepared according to the proportions on the pantone color cards are also not accurate enough. Actually used ink systems and Pantone base color inks will often have obvious color differences. Some factories use Pantone-based ink systems at all. According to the current development of related color matching technology and actual production and application situation, we recommend that the use of computer color matching system, and then appropriately combined with the experience of color matching personnel for spot color ink color matching will be faster, more accurate and more controllable. The system also allows users to easily and easily store and manage a wide range of spot color ink formulation databases for convenient recall.

5, label flexographic printing, anilox roller screen number and net type, network depth, etc., on the label color consistency. More and more labels are now printed on flexo plates. Sometimes when chasing the sample color provided by the customer, even if the prepress, plate, and spot color inks have been consistent with the previous, there will still be differences in the hue of the label spot colors. This may be due to the wear of the anilox roller. Generally speaking, in the flexographic printing, the ratio of the screen lines of the anilox roller and the printing plate is 3:1 or 4:1. Therefore, when using a flexographic printing label, in addition to checking the screen lines and dots of the printing plate, To check the screen number and screen type of anilox roller, the depth of the network. Paying special attention to the difference in the process between the metal anilox roll and the ceramic anilox roll can also cause color differences in label printing.

The above several key points that affect the color reproduction of the label printing, Shanghai Pancai has provided mature solutions for some well-known enterprises in the industry. This has played a very positive role in label printing companies' operability in color control, reducing waste of costs, and increasing production efficiency. It has won recognition from a number of well-known label printing companies represented by Zhengwei.