Offset printing suitability (on)

First, the definition of printability is to adapt to the quality of printing and copying, and to process and technology such as manuscripts, copying, printing, processing and binding, as well as various materials, equipment, environment, and related conditions involved. Requirements, in order to obtain the best quality of all operations.

Second, the relationship between printing and fitness

(a) Letterpress printing: The printed part is indented, and the imprint is surrounded by a framed edge. Suitable for small amounts of forms, business cards, envelopes, stationery, self-adhesive stickers or sets of text or simple illustrations.

(b) Lithographic printing: The printed lines are not convex or concave, and the lines are fine and delicate. Suitable for multi-color prints in black and white and color books, color magazines, posters, advanced letter paper, paper boxes, calendars, newspapers, etc.

(3) Gravure Printing: There are two kinds: 1. Gravure-engraving: The printed part has a protruding feeling when touched by hand, and the ink is thick and strong. Suitable for printing of securities and banknotes. 2. Photogravure - its imprint appears to have a faint dot-like appearance, also like continuous tone. Suitable for large circulation of color miscellaneous

Zhi, plastic film, aluminum foil and other packaging printing.

(d) stencil printing: imprinting into burrs and thick ink layers. Hard and soft printed objects suitable for flat surfaces and curved surfaces, including plastic surfaces, large posters outside the car, printed circuit boards, partial glazing, transfer paper, and fabrics.

(5) Non-engraving printing: The printing methods applied by electronic means include the use of dry toner and liquid ink. The former has a slightly convex pattern on the printed part and the latter is similar to the lithographic pattern. Suitable for small lot, medium and low quality color printing or color printing.

Third, the manuscript's suitability

(i) Texts, ideal conditions should include:

1. Make it clear that the content should not be modified after the manuscript.

2. Editing contains complete edits, chapters, sections, items, etc.

3. Punctuation marks and paragraphs are all intact and carefully arranged.

4. The typo and other characters have been checked and corrected.
(b) The form draft, ideal conditions should include:

1. The lines are clear and the numbers are correct.

2. The decimal point should be correct.

3. The colors of negative or special text and numbers should be clearly marked.
(3) Drawings such as charcoal paintings, Chinese paintings, oil paintings or watercolours, ideal conditions should include:

1. Clear, harmonious tone.

2. Normal color and good texture.

3. The theme is correct and the performance is natural.

4. If the original picture is too large, it must be turned into a positive or photograph, and its color should be the same as the original.
(d) positive or photo, 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 levels are rich.

4. Good composition and good resolution.
Fourth, the appropriateness of the replication technology

(1) Text reprint: Due to the different types of manuscripts, there are printed on paper, written on molded paper, and handwritten on flash paper or other paper. The reflectance is not the same. Special attention must be paid to the revised exposure time when copying. The second is that the visuals of the naked eye and the copying of the plate-making camera are often slightly different. It often takes time and experience to do well.

(B) black and white scan over the net: As the density of the original document often can not match with the scanner, over the net must pay special attention, especially from the bright part to the dark part of the concentration and curve values ​​(or called gamma), or bright Both shades and dark-tone photographs are due to differences in the operator's technology and there are considerable differences in quality. Therefore, at the time of adjustment, it is not difficult to obtain a perfect reproduction by paying attention to and comparing quality differences between manuscripts and reproductions.

(3) Scanning Separation: The control of the color control and the gray balance, and the adjustment and adjustment of the optical department and the sub-optical department, all require some experience in order to do a good job. Sometimes the need to make local color corrections is a difficult operation. It takes many years and months before the operation can be handy.

(D) manual imposition: Before the imposition of the first to take into account the binding method, because of different binding methods, the number and order of imposition will also be different, while the binding, hardcover and paperback the same order, but its reserved The distance between the backs is different, and the binding must be determined before the make-up so as to match the arrangement and the imposition. In the collage, one page should be used for the entire collage. It should not be cut in the film so as to avoid streaks during the printing. This condition is not easy to find during the platemaking. When it is printed on the machine, it is found out and then cured with chemical liquid. Or use a pumice pen to erase, not only a waste of time, but will damage the layout, and will damage the layout, and sometimes there are other problems.

(5) Computer group page: Although this kind of equipment is the latest, except for a few large factories, there are still many printing factories that do not have the ability to purchase such expensive equipment. Although it is fast in operation, it cannot be modified after the output of the film. , otherwise the film must be re-launched, which will increase a lot of costs. Therefore, it is only used for making small version in China, but it does not use it to make large version. The big version still uses manual imposition. Since this operation depends entirely on computer devices, the input, storage, editing, calculation, output, and auxiliary devices are often different due to their different software systems, but the basic principles are similar.

Fifth, the suitability of printing technology

Lithography is very different from other formats. Other formats are mostly direct printing, that is, physical printing in which the printing plate is in direct contact with the paper or the printed body. The lithography is a chemical printing method using the principle of mutual exclusion of water and ink. Therefore, the applicability of its technology is very different from other formats.

(1) Piles of paper: It should be noted that the cross-threads of the paper cannot be mixed and piled together. The entire pile must have a uniform thread flow. Otherwise, the color of the printed products will change due to the paper stretching, and the product quality will not be consistent.

(B) Ink balance: Since the lithographic printing machine must have a wet system to provide layout water. There are three types of systems:

1. Traditional water system.

2. Semi-alcoholic system.

3. Continuous alcohol system.

In order to make the distribution of moisture and ink on the printing plate average, an appropriate proportion should be adjusted to obtain the best printing quality. When the ink is too much, it will cause layout pollution, too little will make the line drawing not print or incomplete. Too much water will make the ink lighter, and vice versa, it will make the wireless part of the layout stained with ink. The alcohol system should pay attention to the composition and proportion of alcohol, and it also has a great influence on quality. Although these are very important tasks in lithographic printing, it is easy to achieve the ideal degree as long as the actual No is working for a period of time.

(C) dusting: There are two types of dusting devices:

1. Universal type.

2. Electrostatic type.

Regardless of the type used, the main function is still to spray a layer of thin powder on the dry ink, so as to keep a little distance with the paper stacked on it, so as to avoid anti-printing. However, 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 poor ink transfer and poor printing on the next overprint or reverse printing. Too little dusting will cause sticking of the upper and lower papers together, anti-printing and other phenomena.

(d) Indoor temperature, humidity, and air flow: These are also the main factors affecting the printing quality. Although it is not directly related to the technology, if the temperature, humidity, and air flow are changed at the top and side of the printing press, the layout water will make Parts are not easy to control. In the past, because the cold air tuyere was on the upper left side of the printing press, the airflow on one side of the printing plate was larger than the other side. Therefore, on the large airflow side, the layout water was easier to dry and the ink-water balance operation was difficult to achieve. Printing technicians are very troubled and cannot get good print quality.