Introduction to Factors Influencing Printing Quality

The quality of printed materials mainly refers to the comprehensive effect of various characteristics of printed materials. The printing process requires multiple processes, and each stage before, during, and after printing is closely related to the quality of the printed product. Any small factor in this process can affect the quality of the printed product. Therefore, to ensure the quality of the printed product, it is necessary to strictly control each link in the printing process, deeply analyze every factor that may affect the quality of the printed product, and adopt effective testing techniques to timely detect and solve problems, further ensuring the quality of the printed product.
1、 The main factors affecting the quality of printed materials
1. Prepress stage
The prepress process generally includes scanning, design, typesetting, plate assembly, plate making, development, and other processes. The factors that affect prepress quality mainly include the following aspects.
1.1 Quality of image scanning
Image scanning refers to the process of converting color information on an image into digital signals through scanning equipment, and processing the digital signals through image processing software, typesetting software, etc. Therefore, the greater the degree of preservation of information such as tone, hierarchy, and saturation on the original manuscript, the greater the possibility of achieving high-quality image replication. This requires setting an appropriate image scanning resolution and an image output resolution with a certain number of screening cables. In addition, when scanning and color-separating images, it is necessary to set the black and white fields and also to correctly set the tone of the black plate. The recorded dot value contrast of the color separation film should be set according to the density range of the original, so that the contrast of the print is as close as possible to the contrast of the original, to accurately reproduce the hierarchy of the original.
1.2 Adjustment of Level Adjustment
Adjust the dark, bright, and intermediate tones of the image to reproduce the effects of each level as much as possible. On the one hand, hierarchical adjustment compensates for the expansion of dots during the printing process, concentrating the main levels in the 10% to 60% visually sensitive area. During the adjustment process, the original manuscript's gradient should be maximized to correspond to the gradient that can be reproduced by printing, so as to make the image clear and realistic; On the other hand, it is necessary to adjust the high, medium, and low-key levels of visual response based on the content and level distribution of the original manuscript.
1.3 Control of color correction and gray balance
The purpose of color correction is to reproduce the colors reflected in the original manuscript. In this process, attention should be paid to referring to specific parameter values, rather than relying on screen display. Grey balance refers to the generation of neutral gray in printed materials by yellow, magenta, and cyan plates in a certain proportion based on different dot area ratios. Its function is to indirectly control all color tones on the screen by controlling the gray part, which is a scale for measuring the correctness of color separation and color matching. Calibrate neutral gray according to the curve during scanning to adjust color deviation.

1.4 Adjustment of image clarity
The clarity of color-printed materials is an important quality indicator for image reproduction and reproduction. Clarity is the sensitivity of image details and edge changes. Sharpening the image in mapping software to improve its clarity, including USM sharpening, sharpening, further sharpening, sharpening edges, etc. Generally speaking, for images with low resolution and small size, smaller radius values should be used to avoid strong contour relief. For images with high resolution and larger size, slightly larger radius values can be used.
Production of 1.5 group versions
Image and text composition is the process of combining scanned images and input text according to the customer's required layout. If the production requirements of the subsequent process are not fully considered during the typesetting process, it may result in all printed products being scrapped. The bleeding position requirement for general printed materials is 3mm, while the bleeding position for packaging boxes is generally 5mm or 7mm. If this standard is not followed during the assembly process, it may increase the error rate of subsequent processes such as cutting and beer boxes, resulting in unnecessary waste. For example, when making a cover, if the thickness of the paper used for the inner pages and the binding method are not taken into account, it may cause problems such as an unsuitable spine or the inability to lay the opened book flat on the table.
1.6 Plate-making process
During the plate-making process, the light source energy, spot technology, resolution, and screening method of the plate-making machine can all affect the image quality of the plate material. Excessive light source energy can easily cause problems such as small dot area and loss of small dots in the layout; The difference between light spot technology and screening methods can affect the restoration effect of network points; The higher the resolution of the plate-making device, the finer the image that can be restored, but the resolution must also match the number of screen cables added to the image. The higher the number of network cables, the higher the requirement for device resolution. At a certain device resolution, a high number of network cables can cause small network points to be lost. In general, matching 2400dpi with 200lpi or 175lpi is more suitable.
1.7 Development conditions
During the development process, the structure, state, and development conditions of the developer can all affect the image restoration effect of the plate material. The type of developing solution in the development tank, the softness and hardness of the brush, the pressure of the transmission rod, and the temperature, time, and uniformity of the development can all affect the loss of the plate coating and the dotted area. Insufficient development can to problems such as enlarged image dots and retained bottom of the layout. Excessive development can cause excessive loss of the plate coating, and the image is prone to problems such as film loss and pattern distortion, all of which can affect the quality of printed products. Therefore, for different types of plates, selecting the matching developer and developer conditions, and adjusting the developer state are very important to ensure printing quality.