Color difference refers to the difference in color. In daily life, we often say that color difference refers to the phenomenon of color difference when visual inspection of products. Especially in the printing industry, the difference between printed matter and standard color samples provided by customers.
In the production process, the color control and judgment methods are basically through visual inspection. Of course, some very experienced people are responsible for this task. However, many factors such as light source, light intensity, observation angle, observation environment, and even the observer's own conditions may affect the judgment of color difference.
There is a certain color difference in the printed matter. We can only judge it according to our own experience and customer requirements, so as to make the printed matter close to the color of the color sample as much as possible. So, how to control the color difference to make the printing close to the color of the design draft? Today, Xiaobian will take you to understand how to control the color difference through the six elements in the printing process.
Printing color matching is the core content of the whole color difference adjustment，Usually, the technicians of many printing enterprises only pay attention to experience or their own feelings in color matching, which is neither standardized nor unified. They just stay in a very primitive color matching state and are very casual.
On the one hand, it has no effect on the improvement of color difference; On the other hand, it is difficult to adjust the hue; Third, there are no appropriate skills to shape the color matching ability of employees.
Special attention should be paid before color mixing Different printing ink manufacturers use different color matching systems to prevent printing ink from falling，It is best to use the printing ink of the same manufacturer for color matching. The color matching engineering must fully grasp the hue and phase deviation of various printing inks, which is helpful to control the color in the process of color matching.
f the remaining printing ink is used before color matching, be sure to find out the hue of the printing ink and check whether the identification card of the printing ink is accurate. It is best to use an ink scraping stick to observe and compare the scraping sample, and then add it. Before adding, strengthen the weighing of the weight and record the data.
In addition, you can also adjust the intensity of spot color ink Color matching by means of Metrology, when scraping the ink color sample, it must be symmetrical and have a white background, which is helpful to compare with the unified standard sample. When the hue reaches more than 90% of the unified standard sample, strengthen the viscosity adjustment. We can make proofing, and then fine tune it.
It is worth mentioning that,In the process of color matching, we must pay special attention to the accuracy of data，The accuracy of the electronic scale is very important for the later summary of process data and parameters. When the ratio data of printing ink is strengthened, through several times of practice, we can quickly and reasonably color matching, and can also avoid the occurrence of color difference.
It is better to mix ink uniformly according to the order quantity, and it is better to complete the color matching work at one time to prevent the hue deviation caused by several color matching. It can reasonably reduce the occurrence of color difference and remaining printing ink.
When checking the color, sometimes the color looks the same even under normal light, but it looks different under another light source. Therefore, a unified standard light source should be selected for color observation or color comparison.
If the doctor blade is often moved in production and processing, the working position of the doctor blade will be changed, which is not conducive to the transfer and color reproduction of printing ink under normal conditions. In addition, the pressure of the doctor blade can not be changed at will.
Before production and processing, it is necessary to adjust the angle and position according to the graphic status of the printing plate roller，When cutting, you must pay special attention to the cleanliness of the action on your hand. The angle of the doctor blade is usually between 50-60 degrees. The doctor blade should pay special attention to the symmetry of the three points of the layout, that is, the ink layer on the left, middle and right should be the same. In addition, before cutting, pay special attention to check whether the three points of the doctor blade are balanced, and there will be no wave shape and one high and one low, which is very important to the hue stability of the printing.
Before production and processing, we should strengthen the adjustment of viscosity, preferably according to the expected machine speed. After adding solvent, we should wait for full mixing before starting production and processing. When the production and processing is accelerated and the product under inspection meets the quality awareness standard, the viscosity can be tested as the unified standard viscosity value of the product. This value should be recorded immediately and accurately and adjusted according to the data of the whole product, which can reasonably reduce the hue deviation caused by the change of viscosity.
For viscosity detection, special attention should be paid to the detection skills. Generally, the main detection body is the printing ink in the printing ink barrel or the printing ink basin. Before detection, the No. 3 viscosity cup must be cleaned to facilitate accurate detection.
In the normal production process, it is recommended to conduct sampling inspection once every 20-30 minutes，The captain or technician can adjust according to the change of viscosity value.
When adjusting the viscosity of printing ink and adding solvent，Pay special attention not to directly impact the printing ink，In order to prevent the system damage of printing ink under normal conditions and the separation of resin and pigment, so as to make the printed matter flower and the color reproducibility is not enough.
Under normal circumstances, we can adjust the air humidity in the workshop between 55% - 65%.
Too high humidity will affect the solubility of printing ink, especially the transfer of shallow screen area is difficult to show normally. Reasonably adjusting the air humidity can improve the ink printing effect and the adjustment of color difference.
Whether the surface tension of raw materials is qualified or not affects the wetting and transfer effect of printing ink on the substrate, the color display effect of printing ink on the film, and it is also one of the factors affecting the color difference.
Ensuring the product quality of raw materials is a prerequisite for quality control,It is very important to choose qualified and reputable suppliers!
Quality awareness: refers to the perception of product quality by production, processing and quality management personnel.
This perception must be obvious and reflected in the details of the work. In terms of adjusting color difference, it is mainly to guide employees to improve their quality awareness, strive for perfection in work and shape the concept of product quality.
When proofing, strictly abide by more than 90% of the standard sample before starting production and processing, and assist the quality inspector to strengthen the inspection of the first piece during the first piece. In the production and processing, the team members are strictly required to perform the quality management system. In the production and processing, if the printing ink hue is changed, pay special attention to the cleaning details of the printing ink basin, and pay special attention to whether the bottom plate of the doctor blade and the clamping strips at both ends are replaced or cleaned in time. If these small details are not paid special attention in the production and processing, color mixing between hues will occur, resulting in color discoloration and color difference.
Color difference is inevitable in packaging and printing. How to avoid or reduce the occurrence of color difference is the key to consider.
Using the specific analysis of the above factors, we can find the improvement skills, further avoid the color difference and control the color difference. Only by realizing the standardization of source and sample management, can we reduce and avoid the color difference, can we make the products between each batch have no obvious color difference, and can we make better products only by paying special attention to the detailed operation and process data management in production and processing, So as to improve the comprehensive market competitiveness of enterprises.