Analysis of Loss and Loss of Lithographic Printing
2018-04-30 09:00:52
As a printing plate that is one of the five elements of lithographic printing, the influence on the quality of the print during printing is very important. In the current lithographic platemaking operations, although the CTP platemaking method has developed rapidly, the traditional printing method is still the main form of lithographic printing. In printing operations, the loss of printing plate outlets is a common fault. The reasons and solutions for this common failure when using positive-printing PS plates for printing plates are briefly discussed for reference by peers.
First, the original factor in the lithographic printing version, the original copy object, the quality of the original will directly affect the quality of the printing plate, the original following factors will lead to the printing plate on the network loss, hair virtual.
1. The original version mistakenly referred to Zhengyang film in lithographic printing, because the lithographic printing is indirect printing, and one of the features of the lithographic printing plate is a reverse image, so it is determined that the reverse printing is needed when the lithographic printing plate is used, but now A considerable number of small-output agencies have low levels of business and do not know much about the printing process. The original version used for lithography is often output as forward film. It is difficult to avoid the loss of dots and small dots when the original printing is used. Therefore, improving the business level of output personnel and strengthening their understanding of the printing process are what some output agencies should do.
2, the original density is low in the film output process, due to film underexposure or over-development, will cause the original density value is lower than the required density of the printing version (general requirements of the original density value of about 3.0). If the original density value is slightly lower than the required value, the dot loss can be reduced by appropriately lowering the exposure time when printing, but if the original density value is too low, only the original plate is replaced.
3, the middle of the film network virtual author in a print, found that the printing plate is always not inked, using many methods will not help, then use the high magnification magnifying glass to observe the original, sent to the original site on the middle of the virtual, thus resulting in the print version The printing plate Internet point is not inked. This may be caused by the improperly focused recording head of the imagesetter during film output.
Second, the exposure process caused by overexposure during the printing process, the exposure of the exposure time to the depth of the printing plate, the positive version of the PS version of the printing time is short, the printing plate is darker, the layout is easy to dirty; on the contrary, exposure For a long time, due to the loss of the version of the network and the deficiency of the version, the edition is shallow, and it is not easy to print when printed. Therefore, the proper exposure time for printing is extremely important.
If you change the lampshade and adjust the distance between the lamps, use different brands of photographic plates or photographic plates of the same brand but different batches. Before the official printing, apply a continuous adjustment ruler, dot ladder or other test strips. Want to use the PS version of the trial printing, find the right exposure time, to ensure the correct transfer of dots in the printing process.
In the actual printing, a considerable number of operators choose the exposure time based on experience, and in the printing process often uses a longer exposure time to avoid dirt on the layout, remove small spots on the layout, this method of text The influence of the edition is not obvious, but for the dot edition, it will cause the loss of outlets and the emergence of virtual phenomenon.
Third, there is a gap between the original and the photosensitive version 1, the vacuum is insufficient In the exposure, the need to vacuum the printing machine drying chamber, so that the original and the photosensitive plate close together. If the vacuum is improperly set or if the vacuum pump malfunctions, the suction tube ages and ruptures, and the weatherstrip sealant strip ages and cracks, vacuum insufficiency will occur. The original and photographic plate will not adhere to each other and cause dot loss and hair voids.
2. If there is dirt between the original plate and the photosensitive plate, the film should be cleaned before it is printed. If the cleaning is not complete, there will be small particles such as sand, etc. on the film. After the plate is developed, there will be dirty spots and dirty. Points around the site will also appear lost, send virtual phenomenon.
3, fight the original group In many books and magazines for printing use, printers for cost considerations, often output small format film, and then use hand-made imposition way to spell the big version. When assembling large plates, the edges of small films may show “wavy edges†or “glitches†when they are cut. These phenomena will cause gaps between the original plate and the photosensitive plate to be used during the printing process. Loss of outlets and occurrence of virtual phenomenon.
In addition, due to the use of adhesive tape to fix the small film on the film base, if the tape is too close to the text or image area, it will also cause the loss of the dots, hair vomiting, or lack of writing.
4, even when the drying cover too close to the original in the printing sometimes encounter the requirement to use a four-open film or even an open film to open the printing version of the situation, in most small printing plants, In this case, it is generally solved by manual solarization. In the case of using a four-shot film for printing, a two-part exposure is required. During each exposure, half of the photosensitive printing plate needs to be covered. If the cover is too far from the original position, it will cause waste of paper during printing; but if it is too close, it will cause the original plate to cling to the photosensitive plate in the process of pumping, so that the dots on the plate will appear. Lost and made false. Therefore, during the continuous drying, the size of the middle seam should be selected according to the size of the paper used for printing.
Fourth, other factors 1, the sensitized version or the original creased version, in the original or photographic plate creases the location of the two can not be very close together, the printing process will cause the loss of the network and the virtual phenomenon. Therefore, it is very important to carefully check the original and photographic plate before printing.
2. Double Exposure The second exposure is the edition of books and periodicals, in particular, a method that is often used when printing out the original printing plate to remove dirt. This method of removing dirt is to use a scattering film to refract light so as to remove the dirty lines and dirt generated on the edges of the film. However, this method also causes the loss of small dots. Therefore, it is not appropriate to use the image printing plate for secondary printing. exposure.
3, over-development of excessive development will not only make small outlets lost, made false, but also reduce the printing plate resistance to printing rate.
4. When repairs are inadvertently repaired, repairing paste or repairing fluids, if eroded to the graphic part, are lost. At the time of revision, the revised paste or revised liquid medicine is rinsed off in time to avoid damage to the layout.
First, the original factor in the lithographic printing version, the original copy object, the quality of the original will directly affect the quality of the printing plate, the original following factors will lead to the printing plate on the network loss, hair virtual.
1. The original version mistakenly referred to Zhengyang film in lithographic printing, because the lithographic printing is indirect printing, and one of the features of the lithographic printing plate is a reverse image, so it is determined that the reverse printing is needed when the lithographic printing plate is used, but now A considerable number of small-output agencies have low levels of business and do not know much about the printing process. The original version used for lithography is often output as forward film. It is difficult to avoid the loss of dots and small dots when the original printing is used. Therefore, improving the business level of output personnel and strengthening their understanding of the printing process are what some output agencies should do.
2, the original density is low in the film output process, due to film underexposure or over-development, will cause the original density value is lower than the required density of the printing version (general requirements of the original density value of about 3.0). If the original density value is slightly lower than the required value, the dot loss can be reduced by appropriately lowering the exposure time when printing, but if the original density value is too low, only the original plate is replaced.
3, the middle of the film network virtual author in a print, found that the printing plate is always not inked, using many methods will not help, then use the high magnification magnifying glass to observe the original, sent to the original site on the middle of the virtual, thus resulting in the print version The printing plate Internet point is not inked. This may be caused by the improperly focused recording head of the imagesetter during film output.
Second, the exposure process caused by overexposure during the printing process, the exposure of the exposure time to the depth of the printing plate, the positive version of the PS version of the printing time is short, the printing plate is darker, the layout is easy to dirty; on the contrary, exposure For a long time, due to the loss of the version of the network and the deficiency of the version, the edition is shallow, and it is not easy to print when printed. Therefore, the proper exposure time for printing is extremely important.
If you change the lampshade and adjust the distance between the lamps, use different brands of photographic plates or photographic plates of the same brand but different batches. Before the official printing, apply a continuous adjustment ruler, dot ladder or other test strips. Want to use the PS version of the trial printing, find the right exposure time, to ensure the correct transfer of dots in the printing process.
In the actual printing, a considerable number of operators choose the exposure time based on experience, and in the printing process often uses a longer exposure time to avoid dirt on the layout, remove small spots on the layout, this method of text The influence of the edition is not obvious, but for the dot edition, it will cause the loss of outlets and the emergence of virtual phenomenon.
Third, there is a gap between the original and the photosensitive version 1, the vacuum is insufficient In the exposure, the need to vacuum the printing machine drying chamber, so that the original and the photosensitive plate close together. If the vacuum is improperly set or if the vacuum pump malfunctions, the suction tube ages and ruptures, and the weatherstrip sealant strip ages and cracks, vacuum insufficiency will occur. The original and photographic plate will not adhere to each other and cause dot loss and hair voids.
2. If there is dirt between the original plate and the photosensitive plate, the film should be cleaned before it is printed. If the cleaning is not complete, there will be small particles such as sand, etc. on the film. After the plate is developed, there will be dirty spots and dirty. Points around the site will also appear lost, send virtual phenomenon.
3, fight the original group In many books and magazines for printing use, printers for cost considerations, often output small format film, and then use hand-made imposition way to spell the big version. When assembling large plates, the edges of small films may show “wavy edges†or “glitches†when they are cut. These phenomena will cause gaps between the original plate and the photosensitive plate to be used during the printing process. Loss of outlets and occurrence of virtual phenomenon.
In addition, due to the use of adhesive tape to fix the small film on the film base, if the tape is too close to the text or image area, it will also cause the loss of the dots, hair vomiting, or lack of writing.
4, even when the drying cover too close to the original in the printing sometimes encounter the requirement to use a four-open film or even an open film to open the printing version of the situation, in most small printing plants, In this case, it is generally solved by manual solarization. In the case of using a four-shot film for printing, a two-part exposure is required. During each exposure, half of the photosensitive printing plate needs to be covered. If the cover is too far from the original position, it will cause waste of paper during printing; but if it is too close, it will cause the original plate to cling to the photosensitive plate in the process of pumping, so that the dots on the plate will appear. Lost and made false. Therefore, during the continuous drying, the size of the middle seam should be selected according to the size of the paper used for printing.
Fourth, other factors 1, the sensitized version or the original creased version, in the original or photographic plate creases the location of the two can not be very close together, the printing process will cause the loss of the network and the virtual phenomenon. Therefore, it is very important to carefully check the original and photographic plate before printing.
2. Double Exposure The second exposure is the edition of books and periodicals, in particular, a method that is often used when printing out the original printing plate to remove dirt. This method of removing dirt is to use a scattering film to refract light so as to remove the dirty lines and dirt generated on the edges of the film. However, this method also causes the loss of small dots. Therefore, it is not appropriate to use the image printing plate for secondary printing. exposure.
3, over-development of excessive development will not only make small outlets lost, made false, but also reduce the printing plate resistance to printing rate.
4. When repairs are inadvertently repaired, repairing paste or repairing fluids, if eroded to the graphic part, are lost. At the time of revision, the revised paste or revised liquid medicine is rinsed off in time to avoid damage to the layout.