Pay attention to the following questions in the printing plate
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1, the proof and the version of the machine
In fact, for proofing and printing, you should print two different versions. For proofing, from the structure of the proofing machine itself, it is generally platform type, the pressure of proofing is smaller than the printing pressure, and the speed is slower than the printing speed. At the same time, because the dot size caused by the proofing is small, when the printing is required, the dot between 2% and 3% is retained, and 98% of the dots cannot be pasted. For printing, because the printing pressure is large and the speed is fast, the printing ink is softer than the proofing ink (small viscosity), which easily causes the dot to increase, and can be increased up to 30% to 40%, so the same plate is used for proofing. The effect is not the same as printing, and this contradiction has not been solved for a long time. Therefore, when printing the printing plate, it is required to retain 4% to 5% of the dots, and 96% of the dots are not pasted, leaving room for the dot enlargement caused by printing, and the printed matter is easy to approach the proof.
2, the phenomenon of losing points when printing
If there is a loss of the dot, you should first check the degree of dot reduction of the film itself. For example, if 50% of the dots on the film are square, 4% and 5% of the dots are complete, etc. In short, check the quality of the photo film, and then judge according to it. Whether the dot is lost in the process of printing. Lost ideas often occur due to problems with the printing operation, which is directly related to exposure time, development time, developer temperature, concentration, and the like. Excessive exposure and excessive developer concentration can cause the dots that should be retained on the layout to be lost or the text strokes to become thinner. Strictly speaking, the printing staff should control the exposure and development through the printing test strip and the gray ladder, and test their own test data.
3, the layout is imaginary
The reason for pursuing the fading of the printing plate may be related to the printing film first. If the exposure is excessive when the film is output, the dot on the printing film will be faint, and the dried version will naturally become imaginary.
From the operation of the printing plate, it may be because the foreign machine or the dirt is attached to the glass or film of the printing machine; or the pad of the printing machine is not suitable; or the vacuum is not solid, so that the film and the plate are tightly bonded. Not enough; improper filming of the film; exposure before (drilling) or after exposure to the development of the light before the development is too strong, etc. may cause the straight face faint; and the developer temperature is too high, the concentration is too high, the development time is too long Excessive development caused by excessive developer solution, etc., is also a cause of the illusion of the plate.
At this point, the glass or film should be cleaned with a cleaning agent; the pad should be leveled; the tape should be placed 3 mm away from the image portion and the film should be in close contact with the plate; in safety light, such as fade-proof fluorescent lamps, yellow light Work with a fluorescent lamp equipped with a safety lampshade; if the development is not suitable, it should be performed according to the standard.
4, uneven development
Uneven development or poor development, often caused by reduced activity of the developer, which is mainly reflected in several aspects: the developer is not replenished in time; the development time is too short; the developer temperature is too low; the rinse solution is reversed, etc. At this time, in addition to standardizing the development conditions, the developer should be replenished in a timely manner.
In addition, the dirty spots or foreign objects on the plate will also hinder the development, which requires the staff to regularly check the developing machine and the printing machine, and clean the machine in time.
5, dirty on the layout
There are different situations on the layout, and there are different reasons. The layout is dirty, it may be underexposed. There are two possibilities. One is that the transparency of the film is not good or the film is out of fog. Second, the exposure light source is used for too long and aging occurs. If you encounter the first case, you can only reproduce the film; if it is a problem with the exposure light source, you should use the gray ladder to adjust the exposure time moderately, or directly change the exposure light source. Of course, poor development may also cause the layout to be dirty. At this time, it is necessary to check the specific cause of poor development and adjust to the standard conditions in time.
In production, sometimes spotted dirt is encountered. Analysis, its "culprit" is quite a lot. For example, there is a dirty spot on the glass of the printing machine, and there are dust or dirty spots on the film; 2 when the film is printed on the film, the tape on the film is printed on the printing plate, and the tape is printed on the printing plate surface; Blisters are attached to cause poor development (developer nozzle holes are blistered due to clogging); 4 fingerprints are left on the plate due to unclean hands during printing operation; 5 protective glue is thin; 6 protective glue is not dry and heavy Stacking and preserving, so that the plates are stuck together, causing the protective rubber layer to peel off when taken; 7 after the plate making, the plate is stored under high temperature and high humidity conditions.
Should be the right medicine for different reasons. Among them, the upper viscera caused by tape adhesive and tape marks is the most common. First, it should be prevented. When making the imposition, use thin and clean transparent tape as much as possible. If the tape adhesive is applied to the plate, it should be gently Wipe off and go to develop. When printing on the plate, fully pump the air to minimize the air layer around the imprinted tape and the original film, minimizing the possibility of light interference. If there is still a tape mark on the plate after exposure, it is necessary to manually remove the dirt with a dirt remover or perform a double exposure to remove dirt.
For other aspects of dirt removal, you can use dirt removal agent, revision knife, pumice stone to remove dirt, you can also use the diffuse film to expose the dirty or dirty cover to remove dirt.
6, poor printing ink
If it is not the ink that is not caused by the sensitizer content of the plate photosensitive glue, the reason should be found from the relationship between the printing force of the printing plate and the exposure time and the concentration of the developing solution. If the exposure time is too long or the developer concentration is too large, the printing ink may be poorly printed. Because the exposed photosensitive layer of the PS plate is not absolutely soluble or absolutely insoluble, but between the two, if the control is not good, the photosensitive layer of the printing plate will dissolve, and the solution will not dissolve, and the ink will be deinked. The rate is increasing and the ink is bad. In addition, if the 1 protective glue is not satisfactory, the glue is too thick, and the manual coating is uneven; 2 the drying temperature of the printing plate is too high or too low, resulting in poor ink absorption or poor film forming property; 3 contact of the printing plate after coating Strong light; 4 plate printing plate stored in high temperature and high humidity environment, will cause the ink to drop. At this time, the protective glue specified by the plate should be used, and the glue should be diluted appropriately to determine the drying temperature reasonably, generally at 60. C or so; after the glue is applied, the light should be protected, and the plated plate should be stored in a qualified environment. If it is found that the printing plate is poorly inked during the printing process, it should be checked whether it is too much glue component in the dampening solution or whether it is not washed with water after using the cleaning agent.
7, the printing plate printing resistance is reduced
The main reason for the decrease in printing durability is the two aspects of printing operation and printing. In terms of printing: 1 before the exposure or before development occurs; 2 film density is not high; 3 due to the high temperature and concentration of the developer, long development time or excessive excess caused by over-expansion; 4 strong acid, strong alkali, organic solvent In addition to the dirty liquid and other chemicals attached to the printing plate; 5 too many times with the plate cleaning agent, etc., these will affect the printing durability of the printing plate. In terms of printing, if the printing pressure is too large or the paper powder is excessive, and a strong plate cleaning agent and a roller cleaning agent are used in the UV printing, the printing durability is inevitably caused to fall.
In particular, it should be pointed out that in order to prevent running light, yellow safety light should be used for the ordinary PS version to fully block harmful light.
8, the dried printing plate has a bottom blue
In the production, one version of the sun came out, whether it was due to the problem of pre-production of the plate, or the matching conditions of the exposure and development time of the sun-printed version were not suitable, and the dried version had a blue bottom. The "secret" of the bottom blue is: 1 when the plate is made, the sand is too thick, the current of electrolytic oxidation is not matched; 2 the exposure is insufficient when the plate is exposed or the concentration of the developer is not enough, or the two conditions are not properly matched. The blue phenomenon causes many operators to have headaches. This problem occurs, and more development is not possible, and less development is not possible. If multiple developments are made, the dots that need to be retained will be reduced or lost; if less developed, the entire layout will be affected. Under the condition of moderate exposure and development, the bottom blue will be dirty after the completion of the shadow, but once it is dirty, there will be a watermark on the plate, and the watermarked plate will be printed on the machine, and the watermark will be around. If you want to get dirty, if you use the repairing liquid to fix the dirt, you will find another circle of dirt. If you are on the picture, text or network, the plate will not be used at all. To solve this problem, it is necessary to apply a thin layer of glue before it is dirty, and high-quality prints cannot use this version.