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How To Control The Consistency Of Label Printing Color
- May 29, 2018 -

In the daily production process, how to maintain the consistency of label printing color has always been a difficult problem for production operators. Many label printing companies have been complained or even returned by customers because of color differences in label products. So, how to control the consistency of product color in the label production process? I discuss with everyone from the following aspects.

Establish a reasonable color management system

We know that it is impossible for prints to completely avoid chromatic aberration. The key to the problem lies in how to control chromatic aberration within a reasonable range. Then, the first step for label printing companies to control the color consistency of label products is to establish a sound and reasonable color management system so that operators can understand the range of qualified products. Specifically there are the following points.

1. Clear upper and lower limits of product color

When we first produce a label product, the upper limit, the standard, and the lower limit of the color of the label product should be formulated. After confirmation by the customer, it is determined as a “proof sheet”. Future production is based on the standard color of proofs and strictly stipulates that color fluctuations cannot exceed the upper and lower limits. In this way, while ensuring the color consistency of the label products, it can also give the production personnel a reasonable range of color fluctuations, and also make the products The color standard is more maneuverable.

2. Improve the first and the end of the sample sign, inspection and sampling system

In order to further ensure the implementation of the color standard, the inspection item of the color of the label product should also be added to the labeling system for the first and the end of the label product, so that the production management personnel can control the difference in the color of the label product. The unsuitable label product will not be passed through. . At the same time, patrol inspections and sampling inspections shall be stepped up to ensure that label products beyond the reasonable range of color differences can be detected and handled in a timely manner during the printing production process of label products.

Printing standard light sources is very important

According to the author's understanding, at present, many label printing companies do not use printing standard lighting sources, which poses a hidden danger for the control of the color consistency of label products. Many label printing companies use the light source to see the colors in the night shift very different from the colors seen in daylight during the day, resulting in printing color differences. Therefore, it is recommended that a large number of label printing companies must use the printing standard lighting source for lighting. Conditional enterprises also need to have a standard light source box so that employees can compare the color of the label products under the standard light source. This can effectively avoid the problem of chromatic aberration of prints caused by non-standard lighting sources.

Ink problems can cause color differences

The author has also encountered such a situation: After the label product is placed in the customer's place for a period of time, its ink color changes gradually (mainly displays the fading), but the first few batches of products did not have the same phenomenon. This situation is generally due to the use of expired ink. The shelf life of common UV inks is usually one year, and the use of expired inks can easily cause the label products to fade. Therefore, when label printing companies use UV inks, they must pay attention to the use of inks produced by regular manufacturers. At the same time, they should pay attention to the shelf life of inks and update their inventory in time to avoid using expired inks. In addition, attention should be paid to the amount of ink additives used during the printing process. If the ink additives are used in excess, the color of the ink may also change after printing. Therefore, when using various ink additives, it is best to communicate with the ink supplier first, and then determine the correct range of additives.

Color consistency of spot color inks

In the label printing production process, spot color inks are often required to be formulated. Many label printing companies have a far cry from the sample color when preparing spot color inks. The main reason for this kind of situation is that the ink ratio is wrong. Spot color inks are formulated from a variety of primary color inks, and most UV inks are PANTONE color systems, so we often formulate spot color inks in the proportion given on the color pass color card. However, it should be pointed out here that the ink ratio on the Pantone color card is not always accurate, and there are often minor differences. At this time, there is a certain requirement for the experience of the printing staff, because the sensitivity of the printer to the color of the ink is very important. The printing staff should learn more and practice more and continue to accumulate experience in this area in order to achieve a proficient level. Here I would like to remind everyone that not all inks are based on the Pantone color system. When encountering non-colortone inks, the ratio on the Pantone color card cannot be used as the basis. Otherwise, it will be difficult to formulate what is required. s color.

In addition, at present, many label printing companies are equipped with electronic scales to ensure the accuracy of the ink ratio. This behavior is worth advocating, and standardization is one of the important measures for the progress of industrial production. The spot color ink prepared for the first time shall be recorded by the operator on the process card in order to provide the data basis for the next preparation of the spot color ink, and at the same time ensure that different shifts and different operators prepare spot color inks. The consistency of color.

Prepress and color consistency

Many label printing companies have encountered such a situation: The color of the label products printed by the customers themselves is far from the color of the samples provided by customers. Most of these problems are caused by the density and size of dots on the plate and the density and size of dots on the sample. In this type of situation, I suggest following the steps to improve. First, use a dedicated wire ruler to measure the number of sample screen lines to determine that the number of screen printing screens is the same as the number of sample screens. This step is very important. Secondly, through the magnifying glass, observe whether the size of the Internet point of each color printing plate is the same as the dot size of the corresponding color of the sample. If they are inconsistent, they need to be adjusted to a uniform or approximate size. It should be noted here that, since the dots after printing will expand, the dot size set at the time of plate making will be slightly smaller than the dots on the sample. Finally, it is observed whether the hue of the printing ink matches the color of the sample ink. Under normal circumstances, can achieve the above three items, the printed label products and customer samples are basically the same color, will not differ too much.

Flexographic Anilox Roller Parameters Consistent with Color Consistency

Many label printing companies have used flexographic equipment to print labels. When they follow the color of the sample provided by the customer, they cannot achieve the same or close to the color of the sample. Look under the magnifying glass to find the dot on the plate. Its size and density are already very close to the customer's sample, and the hue of the ink is also similar. What causes the color difference?

The color of the flexo label product is affected not only by the hue of the ink, the dot size and the density, but also by the number of screen lines of the anilox roller and the depth of the cell site. Under normal circumstances, the ratio of the number of screening lines of the anilox roller to the number of screening lines of the printing plate is 3:1 or 4:1. Therefore, when using flexo printing equipment to print label products, in order to maintain the color close to the sample, in addition to the size and density of the dots in the plate making process should be consistent with the sample as much as possible, but also pay attention to the number of anilox roller screen and the depth of the network , By adjusting these parameters to achieve the color of the label product and sample close to the effect. Of course, flexo printing has unique advantages in terms of color consistency control, that is, its short ink path and metering ink feeding method. Once these parameters are determined, the color of the same type of label will be basically the same for each lot produced in the future.

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