In daily life, we often refer to color difference as the phenomenon of inconsistent colors that occur when observing objects. In the printing industry, color difference refers to the difference in colors between the printed product and the standard sample provided by the customer. It is crucial to accurately evaluate product color difference during the printing process. However, multiple factors, such as the light source, observation angle, and observer's conditions during visual colorimetry, can lead to differences in color evaluation.
So, how can we control color difference to make the printed product closer to the design color? Let's take a look at the six elements of the printing process that can control color difference.
The color adjustment stage of the printing machine is the core link of the entire color difference adjustment. Usually, many technicians of printing companies only focus on experience or rely on their own feelings during color adjustment. This is far from standardized and lacks a unified standard. It only stays in a very primitive state of color adjustment, and the variability is considerable. Conducting color adjustment in this way not only has no effect on improving color difference but also makes it difficult to adjust color tone. In addition, there is no scientific guidance on developing employee color matching abilities.
Before color adjustment, it is essential to prevent the use of print inks from different manufacturers for color adjustment. It is better to use print inks from the same printing machine manufacturer for color adjustment. The color adjustment personnel must have a comprehensive understanding of the color deviation of various print inks to help control color during the adjustment process.
Before color adjustment, if previously remaining print ink is used, it is necessary to first determine the color of the print ink, check whether the label card of the print ink is accurate, and preferably use a scraper to observe and compare the samples. Before adding, weigh it accurately and record the data.
In addition, when adjusting the depth of special color inks, the measurement method can be used to adjust the color. The ink sample should be evenly scraped and placed on a white background to facilitate comparison with a uniform standard sample. When the color tone reaches 90% or more of the standard sample, strengthen the viscosity adjustment, then print a sample and finally make fine adjustments.
It is worth mentioning that it is essential to pay special attention to the accuracy of the data during the printing machine color adjustment process, which is vital for summarizing process data parameters later. When the print ink ratio data is strengthened, the color can be adjusted quickly and reasonably through several practical exercises, which can also avoid color difference problems.
In the production process, it is better to unify the ink matching according to the order size and complete the color matching work at one time. This prevents color deviation and surplus ink problems caused by multiple color matching.
Finally, it is found that even if colors look the same under general lighting conditions, they may not look the same under different light sources. Therefore, it is necessary to choose uniform standard light sources for color observation or comparison.
In the production process, if the scraper is frequently adjusted, it will change the working position of the scraper and hinder the normal transfer and color reproduction of the print ink. In addition, the pressure of the scraper should not be changed randomly.
Before production and processing, the angle and position of the scraper should be adjusted based on the rolling picture and text condition. The angle of the scraper is usually between 50°-60°, and the uniformity of the ink layer in the three points on the layout must be noted, i.e., the ink layer on the left, middle and right must be the same.
In addition, before starting to scrape, special attention should be paid to checking whether the three points of the scraper are installed in balance to avoid the situation of a wave-shaped ink layer or uneven ink layer. This is important for the color stability of the printed product.
Before production and processing, it is necessary to strengthen the adjustment of ink viscosity, preferably by adjusting it according to the expected machine speed, adding solvents after fully mixing, and then starting production. After the accelerated production meets the quality standard, viscosity testing can be performed, and this value can be used as the unified standard viscosity value for the product. This value should be recorded accurately and adjusted according to the data for each batch of products to reduce the problem of color deviation caused by viscosity changes.
Viscosity testing usually focuses on the print ink in the print ink barrel or print ink tray. During normal production, it is recommended to take samples every 20-30 minutes, so that the operator or technician can adjust based on the changes in ink viscosity.
When adjusting the print ink viscosity by adding solvent, care must be taken not to directly impact the print ink to prevent damage to the ink system under normal print conditions, resulting in separation of the resin and pigment, and causing flower prints and insufficient color reproduction on the printed product.
It is more suitable to adjust the workshop humidity between 55% -65%. High humidity will affect the solubility of printing ink, especially in transferring the ink in the shallow mesh area. Therefore, adjusting the air humidity reasonably has a great effect on the adjustment of ink printing effect and color difference.
Whether the surface tension of raw materials is qualified will directly affect the wetting and transfer effect of the print ink on the substrate, the color rendering effect of the print ink on the film, and is also one of the factors that affect color difference. Ensuring the quality of raw materials is a prerequisite for quality control. Therefore, choosing qualified and reputable suppliers is essential.
Quality awareness refers to the perceptiveness of production and quality management personnel on product quality, which is specifically reflected in work details. To adjust color difference, the main factor is to improve the quality awareness of employees, strive for excellence in work, and shape the concept of product quality.