The reason for the printing color difference of offset corrugated packaging
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Almost all color printing has a certain amount of printing chromatic aberration more or less, and the printing chromatic aberration of the offset corrugated packaging is more prominent. This is not to say that the printing of offset corrugated packaging is more prone to color than other printing methods, but because the products of offset corrugated packaging are sub-packages, which are both small and outer packaging, both packaged and individually packaged. Therefore, he belongs to the real high-end packaging. Since it is a high-end packaging, people's requirements for it naturally have to reach the highest standard. We often see a lot of watermark products packaged together, there will be obvious printing chromatic aberration, and people seem to turn a blind eye, but the color difference of offset corrugated packaging products is very sensitive. This is the hope and demand given to people by high-end packaging.
We all know that the main reason for the color difference in high-end color printing is due to the printing dot, because the printing chromatic aberration caused by all other methods is relatively easy to solve. For example, the color hue deviation can be solved by adjusting the ink ratio. The overall color cast color can be improved by adjusting the thickness of the ink layer of a certain color. The overall color of the dot caused by the excessive pressure is too dark, as long as the pressure is reduced. That can be solved. It can be difficult to solve with a color cast, which is local color cast. Usually we will find that there is a region or main pattern with a color cast. This is not a problem that can be solved simply by press adjustment or ink adjustment. At this time, the printing supervisors of many enterprises will solve the problem by adjusting the printing dots of a corresponding color. This kind of solution can generally solve the problem, and only this method can solve the problem. Therefore, it is an effective solution. However, there is a problem we can't avoid. That is, the problem can be solved but it is always unavoidable. Moreover, this problem must be discovered when the printing press is officially printed. Therefore, this time to solve the problem no matter how the result is. , will cause a relatively large loss to the enterprise, because you have to stop to solve, and the long-term downtime will be a large loss.
The main reason for this local chromatic aberration is that the printing plate of a certain color is caused by a soft or hard contrast in the process of sensitization and development. It has been known before printing that if the printing plate is in the process of sensitization, if the sensitization time is too long or the brightness of the lamp is increased, the dot of the shallow net will disappear, and conversely, the density of the shallow mesh dots will increase. This phenomenon has resulted in a very unstable printing plate. This unstable result can't be adjusted on the printing machine anyway. It can only be stopped and dismantled, adjusted the film outlets, and then re-printed, then on the machine, and then try to print, a toss down half a day will pass. Although many companies currently use CTP, similar problems can occur, and although most CTPs are thermally sensitive, similar instability can occur. This kind of instability will inevitably lead to unstable dot density of the printing plate, and the unstable dot density of the printing plate will inevitably cause local color deviation every time printing, so in order to effectively solve this problem, it is necessary to Make sure the dot density of the printing plate is acceptable.
From the comparison results of the above example, we can see that when the contrast of the red dot is reduced, both the almond and the character appear to be reddish overall. At the same time, the red gradient disappears and the gray scale increases. When the contrast of the red dot is increased, the almond is obviously reddish, while the red color of the character is lowered, the face is bluish, the red step is enlarged, the gray scale is reduced, and the red color is bright.
When the blue dot contrast increases, the upper color of the sky becomes darker, the lower color becomes lighter, the overall contrast from top to bottom increases, the brightness of the sky is strengthened, and the spatial sense of the sky is simultaneously enhanced. When the contrast of the blue dot is reduced, the upper color of the sky becomes lighter, and the color of the lower portion becomes darker, and the contrast of the upper and lower portions becomes smaller, so that the spatial sense of the sky is weakened and the gradation is increased.
When the contrast of the yellow dot is reduced, the color of the character and the almond are obviously yellowish, and the color of the character and the almond is gray, dark, not loud enough, and the blue color of the sky is also weakened. When the contrast of the yellow dots is strengthened, the color of the characters and almonds becomes noticeably louder, the face has a rosy feeling, and the color of the almonds becomes full of three-dimensionality, and the blue of the sky is strengthened.
Summarizing the effect of the contrast change of the above three colors on the color, we can conclude that no matter which color (except the spot color), as long as the contrast of the dot becomes smaller, the color will become gray overall. The degree is increased, the level is reduced, and the depth of the color is not deep, and the shallow place is not shallow, which causes the partial pattern color deviation. If the area of the color in the pattern occupies the main pattern, then the reaction will be more prominent. In short, any color dot that is not correct will cause the color cast of the picture, even if the color cast is not obvious, local pattern color cast will appear. If the contrast of the dots of the three colors is too small, then even if the products you print do not have obvious color cast, the overall darkness will inevitably appear, and there is no spirit in the gray. If the contrast of the dots of several colors is too large, the final effect of the product will be obviously bright, and the details of the middle tone will disappear, lacking the layering phenomenon. Therefore, the accuracy of the contrast of the printed dots is a basic condition for the color accuracy of the products you print.
The most prone to the printing chromatic aberration is the following aspects: 1 is the unstable printing machine, 2 is the unstable lighting, 3 is the unstable printing machine and developer. The instability of these three ways will result in the same effect of the same film printing every time. Each time the printing is turned, there will be various unexpected color difference problems. In particular, this color difference is basically unadjustable on the printing machine. Therefore, whenever such a color difference problem occurs, it is necessary to stop and re-adjust the film outlet, thereby causing a lot of loss and trouble to the enterprise.
There is also a situation where many suppliers supply the same package to one enterprise at the same time. The files sent by the customer to each one are basically the same, but the color of the products provided to the customers is always the same. This situation is a very common problem. This is not caused by serious but objective reasons. First of all, in order to confirm the effect, the customer must first make a sample by a certain company, and then distribute the sample and source files to each supplier after confirmation. Now the problem is coming. Every commercial printer can't be exactly the same. Even if it is the same, the paper can be the same. Is the printing machine's length the same? Is the plate making equipment the same? None of these uncertain factors can guarantee the final result. Another problem is worth noting. Although the supplier has confirmed the sample, whether the documents used in the sample can be guaranteed to be the same as the sample, no one can guarantee this, because no matter which company is proofing, it will be based on its own. Features are proofed, so no one knows how big the changes are. Therefore, after the customer has given the samples and documents to the supplier, it may be 80% of the cases, the supplier can not directly produce the source files provided by the customer, because all the prerequisites have changed. Therefore, the source files and samples received will inevitably have a large gap, so you have to adjust the files. As a result, almost all the source file design points have changed. Therefore, it is very difficult to achieve complete color consistency.
In order to ensure the resolution of various printing chromatic aberrations, the patented technology of "Printing Plate Restoration Dot Density Detection System" developed by me can effectively avoid the possibility of printing chromatic aberration in various situations, especially after avoiding the machine. Found the problem, then down the machine to adjust the film, and then on the machine printing phenomenon. It can effectively avoid the problem of printing chromatic aberration, and at the same time reduce the loss of downtime and efficiency of the enterprise, and provide a basic guarantee for the supply of one product by multiple suppliers.
"Printing version restore dot density detection system" is to collect the dot density data of each color in the source file, and then compare the dot density data restored by the printing plate. If the data is consistent, the printing plate can be qualified. Machine printing, if there is a big gap between the data, the system will analyze the data, find the cause of the gap, provide the modification path and adjust the data, and guide the plate maker to make timely and targeted adjustment according to the cause of the problem. In order to ensure that each printing plate is qualified before going to the machine, it can effectively ensure that the printing effect will not be adjusted.
This technology is based on the control of the print version of the data and the source file data is completely consistent, so no matter which company proofing will not cause other suppliers to modify the source file is necessary. In fact, customers no longer need to first sample, as long as a few digital color samples can be solved.
Although the reasons for printing color difference are various, there is only one main source of the problem, that is, there is a big gap between the dot and source files of the printed version, and it is because the gap cannot be adjusted on the printing machine. Whether you are down to the next version of the adjustment network or continue to print, it will eventually bring greater losses to the enterprise. We all know that the next version of the press will have to be shut down for at least a few hours. A few hours may be a loss of tens of thousands of dollars for the company, because it is directly related to the production efficiency of the enterprise, and printing is the first step. The reduction in printing efficiency is related to the reduced efficiency of the entire production line. And the financial data proves that for every 10% reduction in production efficiency, the profit margin will be reduced by more than 50%, and by 20%, then your product is white.
Printing chromatic aberration is a crucial issue for packaging products, especially for some large domestic enterprises, whose packaging is absolutely not allowed to have printing chromatic aberration. As soon as it appears, it must be returned or even destroyed directly. Therefore, if a car or a single item is scrapped, its economic loss may be your one-month net profit. Therefore, to find out the cause of the printing chromatic aberration, and take effective measures to avoid the occurrence of printing chromatic aberration from the source.