Basic knowledge of printing

(a) Classified by printing layout

According to the printing format, printing can be divided into four types of relief printing, offset printing, gravure printing and stencil printing.

If you carefully observe and compare with a magnifying glass with a large magnification, you can roughly determine the kind of printing it belongs to in the appearance of the printed matter.

Any ink printed on the line is piled up, that is, concave copper plate or concave steel plate print, because the gravure ink is mostly piled deeper in the groove, so the ink is relatively thick.

All the screens are covered with white lines, and the ink in the shadows is dark. The light ink in the highlights is ordinary gravure prints. The reason why there is a white line is that the cloth pattern is covered with the screen. This is because when the plate is made, the screen is covered with a sunning wire to prevent the scraper from scraping the ink in the groove of the printing when printing.

The central part of the line or dot is dark ink, the edges are not neat, and there is no pile-up phenomenon. That is the lithographic print. The printed and non-printed portions of the plate are flat, and the edges are not flat due to the erosion of water. At present, color prints in many countries use lithography.

All printed papers have slight markings on the back, and the edges of the lines or dots are neat, and the ink appears light in the center. This is a letterpress print. The raised embossed edges are heavily stressed and thus have a slight impression of protrusions.

All the screens are covered with lines, like the cement walls that wash the stones, the ink in the dark areas is thicker, and the ink in the light areas is lighter. The enamel pattern is formed by contracting the film after developing and washing it, which is similar to the valley formed in the orogeny. It is used to carry the ink.

Others such as cans, curved surfaces and general circuit board printing, multi-hole printing.

(b) Classified by printing procedure

According to the printing production process, there are direct printing and indirect printing.

Direct printing is the contact between the printing ink and the printed matter, and the ink is transferred to the printed material. All letterpress printers (including the latest rubber or plastic transfer machines) and gravure presses, as well as the oldest manual lithographs, are all direct prints.

Indirect printing is that the platen ink needs to be transferred to a cylinder (Cylinder), and then the rubber cylinder moves the ink to the printed material. This is commonly known as a rubber printer.

Direct printing plate, imprinting is reverse image, indirect printing plate, imprinting is positive image.

(c) Classified by printing principle

According to the principles of the printed matter, there are printed parts and non-printed parts of the printing plate, which can be divided into physical printing and chemical printing (Chmiacal Printing).

The physical printing is that the ink is completely loaded on the printed part. If there is no printed part, the printed part is concave or convex. The height of the printed part is different from that of the printed part and cannot be left blank. Therefore, the ink on the printed part is transferred to the printed matter, which is a physical and mechanical function. General gravure printing, letterpress printing, stencil printing, offset printing, etc. Both are physical printing (printing surface is higher or lower than the non-printing surface).

Chemical printing refers to the fact that the non-imprinted part of the printing plate (non-printing side) does not adhere to the ink. This is not due to the fact that the part has low irregularities or is blocked, but it is due to chemical action that causes it to produce a film that absorbs ink and resists ink. . The ink-printed part (printing surface) absorbs ink and resists water, and the unprinted part absorbs water and resists ink. Repulsion of water and grease is still a physical phenomenon. However, in the printing process, the unprinted part should be continuously kept in the water bath solution. To add water-repellent and ink-repellent film, it is necessary to add acids and glues to supply carboxyl-caustic acid from the source, so as to keep the non-printed surface of the plate unaffected by grease, so it is chemical printing. Eraser printing presses fall into this category.

(d) Classification by Printing Color

According to the print color display, can be divided into two types of monochrome printing and multi-color printing. Monochrome printing is not limited to black ones, and all those that display imprints in one color belong to this category.

Poly Color Pritning is divided into three categories: Cosing Method, Register Method, and Multi Color.

The color enhancement method is to add another color in the double-line range of the monochromatic image to make it more clear, vivid, and conducive to reading. This kind of method is commonly used in prints for children's books.

The trapping method is independent of each other, does not overlap each other, and there is no other color as the marginal line of the range, which is overprinted on the printed matter. This method is commonly used for print products such as general line drawings, commodity wrapping paper, and topographic maps.

The complex color method is based on the additive color mixing process, which decomposes a natural color original into a primary color separation plate, and then uses a Subtractive Color Mixing Process to reprint the primary color plate in the same printed image. Physically. Due to the fact that the overlapping areas of the primary colors are not the same, a natural color print similar to the original is obtained. All the color prints, except for a small amount of color enhancement and color registration, are all printed using a polychromatic method.

(five) Classification by printing plate

According to the plate used in the printing plate, there are wood, stone, zinc (aluminum), aluminum, copper, nickel, steel, glass, stone, magnesium, electroplated multilayer, paper , nylon plate, plastic plate, rubber plate and so on.

Wood, stone, glass, etc., because they can not be changed, can only be used for flat bed printing. Copper plates and steel plates are mostly used for gravure printing. The rest is for lithographic or rotary presses.

The alloy version consists of aluminum, yttrium and tin alloy solutions cast in paper type or cast type. There are magnesium, aluminum alloy Miraco Plate, and Monel metal such as copper, nickel, and alloys.

The multi-layer metal plate has a trimetal plate with a chrome-plated copper bottom and a trimetal plate with a chrome-plated copper-layer steel bottom (even with stainless steel).

Due to different media, the printing presses, printing inks, printing techniques and printing effects are also different.

(6) Classified by printed materials

According to the different printed materials, there are paper printing, iron printing, plastic printing, textile printing, wood printing, glass printing and so on.

Paper printing is the mainstream of printed matter, accounting for about 95%. No matter the letterpress, lithographic, gravure, or stencil, it can be applied as ordinary printing.

With printed materials other than paper, many special printing.

(7) Classification by Print Use

Due to the different types of printing business, the use is also different. Such as book printing, news printing, advertising printing, banknote printing, map printing, stationery printing, special printing.

Books and magazines used letterpress printing in the past. In recent years, many lithographs have been used.

News printing, because of its speed and large amount of printing, has been printed on the letterpress rotary press. Recently, in order to meet the needs of color printing, lithographic or photogravure web presses have been used instead.

Advertising printing, including color pictures, pictorials, posters, etc., is mostly lithographic, and some use letterpress, gravure or stencil printing.

The printing of banknotes and other securities is mainly gravure printing. At the same time, it is necessary to use relief and lithography to help meet the requirements.

Map printing is more suitable for photolithography. Because of its large format, high precision, multi-color, print less, the original and more monochrome.

Stationery printing, such as envelopes, letterheads, stickers, business cards, books, workbooks, etc., must be inexpensive and mass-printed. Therefore, quality requirements are not high, so many priority is given to letterpress printing.

Packaging and printing, such as various kinds of halogen sweet vegetable foods, candy, biscuits, candied fruit, as well as various types of packaging corrugated boxes and interior decoration, wallpaper layout, etc., are mostly gravure printing.

Special printing such as bottles, cans, gilding, embossing, hoses, electronics, circuits, labels, tickets, foils.