101. What are the reasons that can cause images to sun?

As long as the photosensitive film of the negative film and the Ps plate does not adhere well, image blemishes may occur. This is for the field and the thicker lines. The influence of the text is not great, but it will have a serious impact on dot and thin lines and small text. The common sun causes are as follows:

1 Shaiban vacuum pump power is not enough, the printing frame is not sealed, the air hole is blocked or the pumping time is improperly set, which causes poor pumping; the pressure drop in the frame is not enough, and the photosensitive film of the film and the PS plate cannot be tightly connected.

2 When the film, light-blocking paper or printing plate is placed, it is not careful, and some of them are exposed outside the printing machine, which affects the seal of the printing frame and causes decompression.

3 There is sand or other impurities between the film and the printing plate; the edge of the film that is hand-picked is not cut cleanly; the edge of the tape paper or the two films overlaps, and the film in the local position is not closely connected with the photosensitive coating of the Ps plate.

4Because the surface is smooth, between the PS plate and the original plate, the surrounding air may be tightly drawn first, and the middle air is sealed because it has been sealed around, so that the middle plate does not adhere to the photosensitive layer of the plate. Therefore, the phenomenon of sun drying appeared. The solution is to use the second pumping method and divide the pumping into two steps. When pumping for the first time, if the pumping is not uniform, interference pattern can be seen. At this time, pumping should be stopped, and the air that is not drawn between the negative and the printing plate will be diffused to the surrounding due to the relatively high pressure and destroy the surrounding area. In the sealed state, after the interference pattern has disappeared, a second pumping operation is performed immediately. After two times of evacuation, the phenomenon of hair deficiencies caused by uneven pumping can be eliminated. Some stencils are automatically evacuated twice.

102. What is the effect of developer concentration on the development quality?

The higher the concentration of the developer, the faster the development speed, but when the concentration is too high, the developer also has a dissolving effect on the photosensitive layer of which no light is seen in the graphic part, resulting in a bad printing plate, a smaller dot, and a lowering of the imprint resistance.

The lower the developer concentration, the slower the development speed. When the developer concentration is too low, the development will be incomplete, the blank will have a blue background, and the full version will be dirty when printed. When this happens, for plates that are not very demanding, they can be redeveloped after adding new developer.

103. What are the factors affecting the developer concentration in production?

1 The amount of the main agent added when the developer is formulated.

2 The number of developed plates. The developing process is the process of reacting the main agent and the photosensitive layer of the printing plate. As the number of developed plates increases, the remaining main agent will become less and less.

3 The time the developer was left in the air. The developer is exposed to the air, and the developing agent base will neutralize the carbon dioxide in the adsorbed air to make the developer liquid fail. Therefore, the developer should be kept as tightly as possible.

104. How does the temperature of the developer affect the development quality?

The higher the developer temperature, the faster the development, but the temperature is too high, the developer solution on the photosensitive layer of the graphic part and the blank part of the alumina have a dissolving effect, it will also lead to poor printing plate. Resistance to force drops and other failures. When the temperature is too low, the development speed is too slow, even at a standstill. The more appropriate development temperature is 18-25 °C.

105. Manual development should pay attention to what issues?

1 Pay attention to control the temperature of the developer.

2 The developer should be placed in a covered tank to reduce the effect of developer's failure due to the adsorption of carbon dioxide.

3 After the completion of the development, pay attention to cleaning the developer remaining on the plate. If the developer is prepared with strong alkali, apply 1% to 3% diluted phosphoric acid to neutralize the remaining developer, and then clean it with water.

106. What problems should you pay attention to when using the automatic processor?

1 The developer should be warmed up and reach the set temperature before starting to use.

2 The developer's rubber roller should not have dry sand, so as not to scratch the surface of the plate. It is necessary to frequently clean the various rubber rollers in the developing tank, especially the rubberized rubber rollers, to prevent the rollers from drying and damage the driving motor.