How to control the consistency of Adhesive Decorative Labels

How to control the consistency of Adhesive Decorative Labels

In the daily production process, how to maintain the consistency of label printing color has always been a difficult problem plaguing production operators. Many label printing enterprises have been customer complaints or even returns because of the color difference of label products. So, how to control the consistency of product color in the label production process? The author discusses from the following aspects and everyone.

(1) Establish a reasonable color management system

We know that it is impossible for printed matter to avoid chromatic aberration completely. The key is how to control chromatic aberration within a reasonable range. Then, the first step for label printing enterprises to control the color consistency of label products is to establish a perfect and reasonable color management system, so that the operators know the scope of qualified products. The specific points are as follows.

1. Define the upper and lower limits of product color

When we produce a label product for the first time, we should work out the upper limit, standard and lower limit of the color of the label product, which is determined as "proof" after the customer's confirmation. In the future production, based on the standard color of the proof, and strictly stipulated that the color fluctuation should not exceed the upper and lower limits, so that, while ensuring the color consistency of the label products, it can also give the production personnel a reasonable range of color fluctuation, but also make the color standard of the product more operable.

2. Improve the sample signing, inspection and random inspection system of the first and last parts

In order to further ensure the implementation of the color standard, the inspection items of the color of the labeled products should be added to the sample signing system of the first and last parts of the labeled products, so as to facilitate the production management personnel to control the color difference of the labeled products, and the unsuitable labeled products will not pass the inspection. At the same time, inspection and spot inspection should be strengthened to ensure that label products beyond the reasonable range of color difference can be found and processed in time during the printing and production process of label products.

(2) Printing standard light source is very important

According to the author's understanding, many label printing enterprises do not use printing standard lighting source, which causes hidden dangers to the color consistency control of label products. Many label printing companies use lighting sources on night shifts to see colors that differ greatly from those seen in daylight during the day, resulting in printing color differences. Therefore, it is recommended that the majority of label printing enterprises must use printing standard lighting source for lighting. Conditional enterprises also need to be equipped with standard light source box, so that employees can carry out color contrast of label products under the standard light source. This can effectively avoid the printing color difference problem caused by the non-standard lighting source.

(three) ink problems will lead to color difference

The author has also encountered such a situation: label products placed in the customer's place for a period of time, its ink color gradually changed (mainly for fading), but the first few batches of products did not occur the same phenomenon. This situation is generally caused by the use of expired ink. The shelf life of ordinary UV ink is usually one year, the use of expired ink is easy to appear label products such as fading. Therefore, label printing enterprises must pay attention to the use of ink produced by regular manufacturers when using UV ink, and pay attention to the shelf life of ink, timely update the inventory, so as not to use expired ink. In addition, attention should be paid to the amount of ink additives in the printing process. If excessive ink additives are used, it may also lead to changes in the color of ink after printing. Therefore, in the use of various ink additives, it is best to communicate with ink suppliers, and then determine the correct proportion of additives range.

(four) spot color ink color consistency

In the process of label printing production, it is often necessary to prepare spot color inks. Many label printing enterprises prepare spot color inks with the color difference of samples. The main reason for this kind of situation is the wrong proportion of ink. Spot color inks are made up of a variety of primary inks, and most UV inks are PANTONE colors, so we tend to make spot color inks according to the ratio given on the Pantone color card. But here to point out that the Pantone color card on the ink ratio is not necessarily completely accurate, often there will be a small difference. At this time, there are certain requirements for the experience of the printer, because the sensitivity of the printer to the ink color is very important. Printers should learn more and practice more, and accumulate more experience in this field in order to reach the level of proficiency. Here I want to remind you that not all inks are based on pantone color. When encountering non-Pantone color inks, you can't use the ratio on the Pantone color card as the standard, otherwise it is difficult to prepare the required color.

In addition, many label printing enterprises are equipped with electronic scales in order to ensure the accuracy of ink proportion. This behavior is worth advocating. Standardization is one of the important measures for the progress of industrial production. The first preparation of spot color ink should be recorded by the operator ink ratio on the process card, in order to provide the data basis for the next preparation of the spot color ink, but also to ensure the consistency of different shifts, different operators preparation of spot color ink color.

(5) pre-press platemaking and color consistency

Many label printing enterprises have encountered such a situation: the color of the label products printed by themselves is very different from that of the samples provided by customers. Most of these problems are caused by the mismatch between the dot density and size of the printing plate and the dot density and size of the sample. In this case, the author suggests the following steps to improve. First of all, use a special cable ruler to measure the number of sample plus cable, in order to determine the number of plate plus cable and sample plus cable number is consistent, this step is crucial. Secondly, the magnifying glass is used to observe whether the dot size of each color printing plate is consistent with the dot size of the corresponding color of the sample. If not, the dot size should be adjusted to be consistent or approximate. It should be noted here that the dot size set for plate making should be slightly smaller than the dot size on the sample because the dot size will expand after printing. Finally, observe whether the color of the printing ink is consistent with that of the sample ink. In general, the above three can be achieved, and the color of the printed label product is basically the same as that of the customer's sample, without too big a difference.

(6) in flexo printing roller parameters related to color consistency

Many label printing enterprises use flexo printing equipment to print labels. Such a situation has occurred: when chasing the color of the sample provided by the customer, it can not reach the same or close to the color of the sample in any case. When looking at the dot above the printing plate under the magnifying glass, it is found that the size and density have been very close to the customer sample, and the color of the ink is similar. So what causes the chromatic aberration?

Flexo printing label product color is affected by ink hue, dot size and density, but also by the number of network lines and the depth of the mesh roller. Under normal circumstances, the number of mesh roller and plate plus network cable number of the ratio of 3∶1 or 4∶1. Therefore, when using flexo printing equipment to print label products, in order to keep the color close to the sample, in addition to the plate making process should pay attention to the size and density of the dot as much as possible and the sample, but also pay attention to the number of roller network cables and the depth of the mesh hole, by adjusting these parameters to achieve the label products and sample color close to the effect. Flexo printing, of course, also has a unique advantage in color consistency control, that is, its short ink path, metering to ink. Once these parameters are determined, the color of similar labels will be basically the same for each batch produced in the future.