Type and characteristics of printing
There are a variety of printing methods, methods are different, the operation is different, and the printed results are also different. Traditionally used printing methods can be divided into: letterpress, Flat, gravure and stencil printing four categories.
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Relief Printing
Whereas the printing surface is prominent, and the non-printed portion is concave, it is called relief printing. Letterpress printing includes both letterpress and rubber printing.
Letterpress
The letterpress printing was developed from early clay type and woodcut type and lead-type movable type. Most of the printing was extended to lead typesetting in modern times.
This printing method is a type of direct printing because it is directly printed on the paper by the printing plate.
The printing plate used for letterpress printing, except for the text part, which uses typesetting, other special characters or patterns, pictures, etc.
Edition method, made of zinc plate (commonly known as the electric version), and more recently developed to nylon offset, improved dot printing effect.
The general letterpress printing version is flat, but in some cases, it is necessary to copy the flat printing plate into a curved version of the lead plate, which can be mounted on a roll type rotation
On the embossing machine, for a large number of printing, such as newspapers.
In addition to printing picture text, typography with some accessories, you can also print the embossed printed surface pattern, you can cut the printed surface (popular
Called beer samples) and printed on paper for the purpose of tearing off the pinholes and printing automatically converted digital characters.
Rubber printing (Flexgraphy)
Rubber printing is similar to typography. The difference is that the printing plate is a piece of soft rubber, like a glue used for stamping. Ink and gravure printing used
Similar, high volatility and thin, used to print adhesive tape and plastic bags.
The method of plate making is divided into three steps: First, the graphic is made into an electrotype for letterpress. Second, bakelite similar to the hard rubber heating pressure in the above
On the electrotype, the printing plate of the hard block is printed. Third, the same female mold is heated and pressed on the female mold with another soft gel, and the first step is obtained.
The same offset printing plate as the original electrotype.
Various types of adhesive tape, such as cellophane, P, V, C glue, Polyester, Acetate, etc.
Materials with no absorption and penetrating ink properties on the surface can be printed on it. Applicable to plastic bags, hand pumping, size plastic packaging. But this type of printing
The printed dots and lines of the method are not as good as offset printing and letterpress printing. Therefore, the picture should emphasize the large effect.
Lithography (Planography)
Basic principles of lithography
Lithography was named after the early lithographic printing. The early lithographic printing was applied after the stone had been leveled and then modified to metal.
Zinc plate or aluminum plate is a plate, but its principle is unchanged.
Where there is no difference between the printing part and the non-printing part, that is, it is a flat surface, the printing part is maintained by the water-oil non-mixing principle.
A layer of grease-rich oil film, but the layout on the non-imprinted part can absorb the appropriate moisture, imagine the ink on the layout, the printed part
It rejects water and absorbs ink, while the non-printed part absorbs moisture to form an ink-resistant effect. This method of printing is called
"Lithography."
After the lithography was developed from the early lithographs, its platemaking and printing had its own unique personality. At the same time, it was extremely simple in work and low in cost.
In the modern era, it has been constantly studied and improved by experts, and has become the most used method in printing today.
Lithography
The lithographic printing method was developed from the early lithographic printing transfer method, and it was described on the transfer paper and fell on the plate to become anti-printing, and then printed.
On the paper is a positive pattern. Due to the pressure exerted by this method during printing, the lithographic plate is originally a flat plate (ie, an imprinted portion and a non-imprinted portion).
The parts are all flat. After the pressure is applied, the ink on the printing plate expands and dilates, resulting in poor line drawing.
Later, it was modified to be called Offset Printing (offset printing). The printing method was to make the layout into a positive pattern, which was transferred to the eraser during printing.
Anti-pattern on the cartridge, and then anti-grain printing on the paper is a positive pattern, so that you can improve the elasticity of the printing pressure.
The early lithographic printing was lithographic flat pressing, and later it was developed into two types of flat round press type and round type round press type, and most of the flat round press type machines made
Used for special printing, such as proofing machines for proofing, etc. As for machines such as printing paper, all round rotary presses have been improved. Flat round press type
That is, the printing plate is laid flat, and the pressure part is a drum-type cylinder. This printing mode is similar to the lithographic rotary press machine in relief printing.
The round plate type is called the plate cylinder by enclosing the printing plate on the cylinder. The other cylinder on the machine is called the rubber cylinder by the rubber plate.
The same type of roller cylinder is used. This kind of machine with three basic rollers is called "Offset Printing Machine".
Advantages and Disadvantages of Lithography
1 advantages: plate making work is simple, low cost. The color plate is accurate and the printing plate is easy to copy. The print is soft and soft. Can print large numbers
Volume printing.
2 Disadvantages: Due to the influence of water gel during printing, the tone reproduction power is reduced and the vividness is lacking. The layout ink is thin (only can show 70% ability, so
Offset printed light box posters must be double-sided printed to enhance their color). Special printing applications are limited.
Application range
1 poster, 2 simple price, 3 manuals, 4 newspapers, 5 packs, 6 books, 7 magazines, 8 calendars, 9 other related color printing and large numbers
The amount of printed matter.
Intaglio Printing
Basic principle of gravure printing
There is a lot of difference between the printed part and the non-printed part, which is the opposite of the letterpress, that is, the part of the printing plate has obvious concave shape on the layout.
Below, the non-printed part is glossy and smooth. When printing, the ink needs to be rolled on the plate first, then the ink naturally falls into the printed part of the depression.
Afterwards, the surface-adhesive ink is wiped off (of course, the recessed ink will not be rubbed off). Put a larger pressure on the paper after putting the paper
The imprinted ink is imprinted on the paper. Those who use this printing method are called "gravure printing."
Gravure Printing
Due to the heavy printing pressure in the gravure printing method, printing is performed in more than the relief or lithographic printing, and the pressure on the printing plate is also increased.
Special attention must be paid to the printing method being the reverse pattern of the layout and the printing paper surface being the regular pattern.
Gravure printing is divided into engraving gravure and gravure
(Photogravure)
1 engraving gravure:
Engraving intaglio was an early evolution of metal-engraving carvings. At that time, the engraving copper pattern was used as an ornament. Later, it was used in the printing table.
Now on.
The copperplate printing paper used for engraving gravure is wet first, mainly to increase the adhesion of the co-ink, so the back of the paper needs to be padded.
Thick cloth, and with a large pressure, can draw the ink stuck in the printed mark on the paper and print it on the paper. This printing method is mainly lacking.
The point is that it needs to be dried after printing, which will produce irregular stretching and contraction, which will cause the printed products to have uneven length. But now the copperplate printing has been improved.
For dry printing, the layout is improved and the lines of the engraved depressions are made shallower. Make the ink it sticks easy to pull out. According to copperplate printing and steel plate
Printing for the depth of the pattern, the thickness of the lines and the depth of the three-dimensional sense, the thick and deep printing plates, the adhesion of the ink
Thick, so the ink color is darker. Thin, thin plates have a thin, sticky ink, so their ink color is lighter. Such print
It's as beautiful as the modern visual art design, but most of it is used to express patterns or text, as for a continuous color like a photo.
(Continuous-tone) is harder to do.
2 gravure
Photogravure is also called photocopying, which is to use the principle of photography to corrode the copper plate. It is a kind of adhesive paper which has been treated by potassium dichromate solution.
The (Larbo Tissue) and gravure dedicated screens were exposed, and then the adhesive tape and the continuous version were transferred to the positive film for printing.
After two exposures, it can be developed by warm water. The black and silver on the positive film of the screen light part of the adhesive tape is lighter, and the adhesive tape is transmitted by the light wave.
The degree of hardening is higher, so the film after water development is thicker, and the adhesive tape in the dark part of the picture is affected by the thicker black silver of the positive film.
The adhesive tape can be light-wave-transmitted and hardened to a lesser extent, so that the film developed after water is thinner. Therefore, this developed and thick adhesive
The paper is affixed to a copper roller or a flat roller and is eroded with ferric chloride. The thicker part of the light part of the light film penetrates and erodes the depth of the copper plate.
The degree of lightness will be relatively shallow, so its sticky ink film is thinner, and the ink color it prints is lighter. As for the film where the dark part film is thinner, the glue thickness may be soaked.
Through the etching into the copper plate must be deeper, so the ink sticking the printed pattern will be thicker, and its ink will be printed deeper.
Gravure printing advantages and disadvantages
1 Advantages: The ink has a performance of about 90% and is rich in color. Strong color reproduction. The layout is strong. The number of prints is huge. Application paper range
Extensive, materials other than paper can also be printed.
2Inferiority: The plate making cost is expensive, the printing fee is also expensive, the plate making work is more complicated, and a small number of prints are not suitable.
Gravure printing application
Engraving gravure printing is used for printing valuable securities such as banknotes, stocks and gift certificates because of its exquisite lines and not easy to counterfeit.
, voucher and stamps of business credit or stationery, etc. Due to the high cost of its plate-making and printing, there are few general printed materials.
As for the photogravure, although its plate making process is more complicated and its cost is also more expensive, it is not suitable for printing a small number of imprints.