Lithographic suitability (on)
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First, the definition of printability
In order to adapt to the quality of printing and reproduction, the requirements for the process and technology of manuscript, copying, printing, processing and binding, as well as the various materials, equipment, environment and related conditions involved, in order to obtain the best quality Everything to do.
Second, the relationship between printing and fitness
(1) Letterpress printing: The printed part is concave, and the border around the print has a feeling of frame. Suitable for small forms, business cards, envelopes, letterheads, self-adhesive stickers or sets of numbers or simple illustration prints.
(2) Lithography: The print does not protrude or recess, and the print is fine and beautiful. Suitable for multi-color printing of black and white and color books, color magazines, posters, advanced letter paper, paper boxes, calendars, newspapers, etc.
(3) Gravure printing: There are two types, 1. Engraving intaglio--the printed part has a convex feeling when touched by hand, and the ink is thick and strong. Suitable for printing of securities and banknotes. 2. Photogravure - its prints appear to have faint dot-like dots, and seem to be continuous. It is suitable for large-volume color magazines, plastic films, aluminum foil and other packaging and printing materials.
(4) stencil printing: the printed pattern is burred and the ink layer is thick. Hard and soft printed objects suitable for flat and curved surfaces, including plastic surface, large posters outside the car, printed circuit boards, partial glazing, transfer paper, fabrics, etc.
(5) Non-printing: There are two types of printing methods, which are dry toner and liquid ink. The former has a slightly convex print, while the latter has a similar approximation to the lithography. Suitable for small batches, medium and low quality color or color prints.
Third, the suitability of the manuscript
(1) A draft, the ideal conditions should include:
1. Write clearly, the content of the manuscript should not be modified.
2. Edit complete contains editors, chapters, sections, items, etc.
3. Punctuation marks and paragraphs are complete and carefully arranged.
4. The typo and other characters have been checked and corrected.
(2) The draft, the ideal conditions should include:
1. The lines are clear and the numbers are correct.
2. The decimal point should be correct.
3. The color of negative numbers or special texts and numbers should be clearly marked.
(3) Drawings such as charcoal painting, Chinese painting, oil painting or watercolor painting, the ideal conditions shall include:
1. The level is clear and the harmony is harmonious.
2. The color is normal and the texture is good.
3. The theme is correct and the performance is natural.
4. If the original painting is too large, it must be turned into a positive film or a photo, and its color should be as similar as possible to the original.
(4) Positive film or photo draft, ideal conditions should include:
1. The exposure is correct and the concentration is good.
2. The image is sharp and beautiful.
3. The contrast is appropriate and the level is rich.
4. Good composition and good resolution.
Fourth, the adaptability of replication technology
(1) Text re-examination: Due to the different types of manuscripts, there are different types of manuscripts printed on the plate, written on the paper, and written on the edging paper or other paper, the reflectivity is different. Special attention must be paid to revision exposure time when copying. Secondly, the visual results of the naked eye and the reproduction results of the plate-making camera are often slightly different. It often takes time and experience to do a good job.
(2) Black and white scanning network: Since the concentration field of the original can not be matched with the scanner, special attention must be paid when passing the net, especially the concentration field and curve value (or gamma value) from bright to dark, or bright Both tonal and dark-tone photos are subject to considerable quality differences due to the operator's skill. Therefore, when adjusting, always pay attention to the difference in quality between the original and the copy, it is not difficult to obtain an ideal copy.
(3) Scanning color separation: Color control and gray balance control, as well as control and adjustment of the light department and sub-light department, require some experience to be done well. Sometimes it is difficult to do local color correction, and it takes a lot of work experience to be handy.
(4) Manual imposition: Before the imposition, we must first consider the binding method. Because the binding method is different, the number and order of imposition will be different, but the order of glue, hardcover and paperback is the same, but it is reserved. The distance between the backs is different. Before binding, you must decide the binding method to match the layout and layout. In the collage, you need to make a whole page of a page. You can't cut it in the film to avoid streaking during the printing. This situation is not easy to find in the plate making. When it is printed on the machine, it is repaired with chemical liquid. Or grinding with a pumice pen is not only a waste of time, but also damages the layout, and it will damage the layout, and sometimes other problems will occur.
(5) Computer group page: Although this equipment is the latest, in addition to a few large factories, there are still many printing factories that are not capable of purchasing such expensive equipment. Although it is fast in operation, it cannot be modified after outputting the film. Otherwise, the film must be re-released, which will increase the cost. Therefore, it is only used in the domestic production of small version, instead of using it to make a large version. The large version still uses manual imposition. Since this operation relies on the computer device, the input, storage, editing, calculation, output, and auxiliary devices are different due to different system functions, but the basic principles are similar.
Fifth, the suitability of printing technology
Lithography is very different from other layouts. Other layouts are mostly direct printing, which is the physical printing method in which the printing plate is in direct contact with the paper or the printed body. The lithograph is a chemical printing method that uses the principle of mutual exclusion between water and ink. Therefore, the suitability of other technologies is quite different from other formats.
(1) Stacking paper: It should be noted that the vertical and horizontal flow of the paper cannot be mixed and piled together. The whole pile must have a consistent flow of silk. Otherwise, the color of the printed product will change due to the expansion and contraction of the paper, and the product quality will not be consistent.
(2) Ink balance: Since the lithographic printing machine must have a wetting system to supply the water. There are three types of systems:
1. Traditional water system.
2. Semi-alcohol system.
3. Continuous alcohol system.
In order to average the amount of water and ink distributed on the plate, an appropriate ratio of adjustment is required to obtain the best print quality. When there is too much ink, it will cause plate contamination, too little will make the line print not incomplete or incomplete. Too much water will lighten the ink, which in turn will cause the ink on the plate to be stained with ink. The use of alcohol systems should pay attention to the composition and proportion of alcohol, which also has a great impact on quality. These are lithographic jobs A very important job, but as long as the real No work for a while, it is easy to achieve the desired level.
(3) Powder spraying: There are two types of powder spraying devices:
1. General purpose.
2. Electrostatic type.
Regardless of the type used, the main function is still to apply a thin layer of powder to the dry ink to keep a little distance from the paper stacked on it, so as to avoid counter printing. However, both the quality of the powder and the amount of powder to be sprayed must be paid special attention. Poor quality or too much dusting will cause the ink to be poorly transferred to the next overprint or back printing, and the ink is not good enough. Too little dusting will cause the upper and lower papers to stick together and the prints to be reversed.
(4) Indoor temperature, humidity and airflow: These are also the main factors affecting the printing quality. Although it is not directly related to the technology, if the temperature, humidity and airflow change above and on the side of the printing machine, the water will be made. It is not easy to control. In the past, because the air-conditioning vent was at the upper left of the printing press, the airflow on one side of the printing plate was larger than the other side. Therefore, on the side of the large airflow, the water content of the printing plate was easier to dry, and the work of balancing the ink and water was difficult to achieve. Printing technicians are very troubled and cannot get good print quality.