Stencil quality five elements

Shaiban is a "bridge" process in platemaking and printing. Its status is very important. The quality of the printing plate not only directly affects the quality of the printed matter, but also directly involves the production cost. Here only on the personal work experience, the PS version of the printing quality problems specific analysis and discussion, exchange of experience in order to improve the quality of the PS version of the printing version, improve the PS version utilization.

one. The image is imaginary and dirty

1. The adhesive tape on the film is too close to the image, the image pad is imaginary, and the tape paper is dirty; when the imposition is over, the image pad is imaginary and there are also dirty marks. Solution: Keep the tape or imposition base as far as possible to avoid imagining. The dirt on the tape can be removed with a dirt remover or removed with a double exposure of a scattering film.

2. Dust, sand, and other dirt are deposited on the PS plate, causing the image to become dirty on the pad. The team must carefully check the layout, remove all the dust, and do a good job of indoor hygiene. The ideal is to print in a dust-free environment.

3. The glass is unclean during printing, and there are glue points to dirty the image pad. According to the operating process requirements, the glass must be wiped clean before printing, otherwise it is not allowed to print.

Second, the blank part of the printing plate is dirty

1. Insufficient exposure resulted in incomplete decomposition of the sensitizer and incomplete removal of the development, causing the blank part of the printing plate to become dirty. If the printing plate is not printed on the machine, it can be rescued by the second development method, but this rescue is only applicable to the case where the exposure is slightly insufficient. In severe cases, it cannot be saved. Determine the appropriate exposure time is the key to determine the quality of the printing plate, you can use a continuous ash scale test, so that the density of O.45 does not absorb ink, you can effectively solve the problem caused by the exposure of the plate dirty.

2. Insufficient development, non-image sensitive film removed, resulting in dirty plates. The reasons are as follows: 1 The concentration of the developer is insufficient; 2 The development time is insufficient; 3 The temperature of the developer is low, and the ideal developer temperature is (22±2)°C.

3. PS photosensitive layer coating is uneven, the thickness is inconsistent, the degree of decomposition of the photosensitive resin when the printing plate is different, causing the upper dirt. For example, the emulsion coated with a centrifugal baking machine often appears radiating, and the four sides are easy to get dirty. This situation can be rescued by local exposure or partial development.

Third, the printing plate does not absorb ink

1. Overexposure: 1 The original density is too low, the photo transmission light when printing; 2 exposure time is too long; 3PS version is not properly preserved, light leakage, long shelf life, deterioration, poor ink absorption.

2. Excessive development: 1 developer is too strong, too alkaline; 2 too long development time; 7 developer temperature is too high.

According to the different characteristics of different manufacturers of different grades of the PS version of the sensitizer, the use of a suitable formulation, ratio of the developer, test and control with the test strip, is an effective way to steadily control the development quality.

3. The protective glue changes acid and deteriorates. This is often the case in the summer months of high-temperature plum rain. The glue is not uniform, and the rubber path is produced, resulting in no ink absorption.

Fourth, the graphic is too shallow

1. Excessive exposure should reduce the exposure time;

2. Over development, should reduce the development time;

3. Insufficient density of the original plate, transmission of light during printing, making the outlets smaller;

Fives. Picture is too deep

The reason why the graphic is too deep is often the opposite of the reason that the graphic is too light, and the solution is the opposite.

1. Insufficient exposure should increase the exposure time;

2. Insufficient development should enhance the development;