Ink color matching technology (3)
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Computer color matching and manual ink adjustment
From the green measurement of the previous period as a demonstration, the formula obtained from the computer operation (Fig. 1), the selected formula has a ΔE of 0.28, an MI of 0.73, and a CFI of 1.67. Because it is a test relationship, the author only allocates 20g ink (Table 1). Use the electronic balance to extract the required components (Figure 2), pay attention to the weight of the component, because the component is small, so it is accurate to 3 decimal places. If the component exceeds 10 kg, the error value can be retired to single digits. Thoroughly mix the ink, and then use the IGT printing suitability to print the color sample (Fig. 3). Determine the reproducibility of the spot color copy from three different light sources and whether there is a metamerism. . (Fig. 4) Under the light source of 5000K (Fig. 5) under the light source of 6500K (Fig. 6) under the A light source
For guests and printers, judging is a very important process under three different light sources, because considering the problem of metamerism, it can reduce the difference of color in different color temperature environments, and reduce the chance of future debates. This is the traditional color scheme. The benefits of the method are not. Wait for the color sample to dry to about 70%, we can measure the color sample, input the actual color data to the computer, and then compare the formula calculated by the computer first, observe the difference of the color between the two colors from the color tolerance △E (Figure 7 ).
Whether the results obtained by the computer are acceptable or not depends, of course, on the range of color differences we have set. In general, we recommend a qualified color difference range between ΔE1.5-2.0. If you are qualified, you don't have to worry about other things. However, the use of manual ink adjustment and scale ink, always give us a certain degree of error, such as weighing methods and ink adjustment techniques, etc., it is very normal to make a fine adjustment. If the result from the first completion is considered to be ideal within △E=2.2, then what is the difference, what should we do?
At this time, the computer knows the color sample data, and then compares the computer's original recipe data, through the recipe correction function (Formula Correction), by inputting the remaining components, it automatically calculates what components we need to add to achieve the spot color we require. How much to add depends on the error between the color sample and the standard that has just been completed. According to experience, if the difference between △E and the pass is less than 0.5, it is only necessary to add about three to five percent of the ink to reach the qualified range. At the same time, you should pay attention to the true meaning of this function, not just to change the formula obtained by the computer, but to recycle the old ink.
Old ink rebirth
I believe that you will have a lot of old inks that have been abandoned in the factory. Everyone has been thinking about how to deal with them. How to apply them is also a big problem. How can we help to arrange these old stocks through the color matching system?
As mentioned above, the recipe change function in the system is actually very simple. First, the spot color sample is used to measure the data, and then the old ink is used to make the color sample through the ink proofing machine, and then the data of the old ink color sample and the remaining components are measured. Computer, at this time the computer compares the long-stained ink with the spot color sample and analyzes the spectral data of both parties, then the computer will find the corresponding ink in our ink database, and calculate what kind of what to add and what The component ink can reach the color of the spot color sample. The advantage of this method is that it can reduce the application of new inks, reduce production costs, and reduce the space for storing old inks. From then on, everyone will no longer have to take them to adjust the black and gray. However, when you use the old ink color matching, you should pay attention to it. Try to use the ink of the approximate hue as much as possible. That is to say, the blue color is blue, the red color is red, and the old ink is not used to match the yellow ink. Can reduce the waste of more ink.
Predicted ink concentration
In fact, in the process of traditional color matching, we often ignore the importance of ink concentration. For example, in the color check of the traditional color matching, a small amount of ink is first taken by the human hand, placed on the paper, and pressed through the plane between the paper and the paper as a proof. Although this method of checking the color matching is convenient and quick, the ink concentration is often neglected and the stability is lacking. On the other hand, it is impossible to know exactly what ink concentration is required in actual production. Using computer-calculated recipes, you can clearly grasp these data.
In actual printing production, the concentration is an important part of the influence of the color depth. When using the computer color matching, you can input the minimum ink layer thickness requirement first. Generally, it is recommended to be 1.0μm, 1.2μm, etc. Under the limitation of thickness, the computer may not be able to calculate the required formula, so we have to try different thicknesses in order to find the most suitable ink thickness. According to the relationship between the thickness of the ink layer and the printing density, we can know the production requirements. Ink density. Of course, the thicker the ink layer, the more the ink component used in printing, and the most similar color is produced using the lowest concentration. However, sometimes, because of the influence of the background color of the paper, we need to increase the concentration and increase the coverage of the ink. If the effect is still not satisfactory, the computer may be required to add white ink or black ink, and then recalculate the formula.
Ideal and not ideal
The author constantly mentions the benefits of computer color matching in the text. In fact, as a printer owner, technical department or purchasing department, should you introduce such a system? We give you some advice.
Order percentage
The amount of ink used in the order
Production time
The first is to consider the percentage of spot color orders, which is the amount of work in the factory. On the other hand, it is the amount of ink used for spot color in the order. If it is about 10kg, it can be greatly reduced in time and cost by hand-adjusting ink and matching with computer color, because it can be freely controlled in terms of ink type. Use four colors each time, then consider adding other expensive inks. In addition, it is no longer necessary to spend a lot of time to test the master, the formula of the computer is actually a shortcut, and the ink used has been brought out. Also, it is no longer necessary to spend time to send the color samples to the ink factory, and then wait for the reply and price of the ink factory. Finally, it is able to accurately control the amount of ink, because the formula gives 10kg is 10kg. Different from the previous hand, when the color is matched by hand, it is 8kg from 3kg, and the remaining 5kg becomes loss. However, in the opinion of the individual, manufacturers who usually print under 10kg of spot color choose to use the hand to adjust the ink and then match the computer color matching, which can best exert the most ideal effect.
In the author's mind, an ideal color matching system is not a combination of computer and manual, because the fastest and most accurate method is to use computer to calculate the formula, and then through the small leaker (Dispenser) (mainly below 20kg) The required amount of ink is automatically adjusted, and then sent to the ink mixer to mix the ink. This can be sent directly to production and directly on the press. At this point, Master only needs to adjust the ink spoon on the printing press to control the concentration and ink balance to get the desired result.