How to reduce and control color difference in packaging bags

The color of the ink, when used in printing, often has a discrepancy with the standard color. This is a problem that is difficult to completely avoid; we can only minimize the color difference. What causes this problem, how to control it, and how to improve the accuracy of ink color matching? Today, Shunxingyuan Packaging, a professional flexible packaging manufacturer, will give you a detailed explanation.

1. Printing Method

Most ink factories use small British imported printing machines. The mesh of this type of machine is on a flat plate, and the printing is completed by moving the printing film with a round embossing roller. The printing factory's machine uses a round-to-round method, and the mesh is on a rotating cylindrical roller. The line number, angle, etc., of these two types of meshes have significant differences, which makes the same ink have considerable differences under the two printing methods. Sometimes, it's not just a matter of light or dark color depth, but also the hue and brightness, which can lead to significantly different effects. Some small factories use a scraper to match samples, which is even worse.

Using the proofing machine from the plate-making factory to match the color will be much better than using a small imported printing machine, while the price is almost the same. This proofing machine can produce plates similar to those of a printing factory and can design printing patterns of different levels and depths as needed. This makes the printing method basically the same as that of the printing factory, Simultaneously The printing plate is also the same as that of the printing factory.

2. Plate Depth

Different prints have different plate depths, and the ink factory's understanding or estimation of the plate depth used for the print also affects the accuracy of color matching. Obviously, if the ink factory uses a 45μm deep plate for color matching, but the customer's plate is much less than 45μm, the printed color will be lighter; conversely, it will be darker.

Some people believe that ink matching is done according to the standard ink provided by the user, and the plate depth need not be considered. This is a theoretical view, but it is not the case in practice. Theoretically, two identical inks (e.g., dividing a cup of ink into two portions) will have the same hue regardless of the depth of the plate (other conditions being the same). However, in actual color matching, it is impossible to prepare two exactly identical inks, so there is often such a phenomenon: sometimes the color of the shallow plate is closer (can meet customer requirements), but if the deep plate is used, the color difference is much greater. Therefore, mastering the plate depth is very important. The depth of the customer's plate must be used for color matching.

3. Viscosity

The printing viscosity of ink factory color matching should be as consistent as possible with the printing viscosity when the printing factory prints the ink. The greater the difference between the two, the greater the final color difference. The ink factory uses 22s for color matching, while the customer uses 35s. In this case, the color will definitely be much darker; conversely, it will be much lighter. Some ink factories do not pay much attention to this issue and do not consider the printing viscosity of the printing factory. They uniformly use a unified viscosity to compare the customer's standard samples (ink samples and print samples), which results in a large color difference.

4. Printing Materials

If the materials used by the ink factory for color matching are different from those of the printing factory (including other processes), it will also cause a large color difference. Some inks will be closer to the customer's prints when an additional layer of white ink is printed, while others are the opposite. Some change little after lamination, while others change significantly, such as some transparent colors. Therefore, when matching ink colors, it is necessary to understand the customer's process, including the basics: whether to print a white ink base, what materials to laminate, and whether to apply a UV coating.

Theoretically, the closer the printing conditions during ink factory color matching are to the conditions when the printing factory uses the ink for printing, the higher the accuracy of the matched ink. However, due to limitations, there are still many differences between the two, such as printing speed, the environment for viewing colors, and the pressure of the printing rollers, which cannot be unified. As long as these four parts are well controlled, the accuracy of ink color matching in the ink factory can be greatly improved, thus printing exquisite packaging bags with small color differences. 。