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 four categories: letterpress, lithographic, gravure and stencil 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.
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. At the same time, this type of printing method was directly printed on paper by printing plates. A direct printing.
Printing plates used in letterpress printing, except for the use of typeface for typesetting in the text part, and others such as special typefaces or patterns, pictures, etc., use a photoengraving method to make a zinc plate (commonly referred to as an electrotype), and recently developed into a nylon offset plate. Improved dot printing effect.
The general letterpress printing version is flat, but in some cases, the flat printing plate needs to be copied into a curved version of the lead plate, which can be mounted on a roll type rotary printing machine for a large number of printing, such as newspapers, etc. .
In addition to printing picture texts, letterpress printing adds some accessories, and can also print embossed face text patterns, which can cut the seal face (commonly known as beer sample) and print the pinhole line for tearing the paper and printing automatically Transposition of digital characters.
Rubber printing (Flexgraphy)
Rubber printing is similar to letterpress printing, except that the printing plate is a piece of soft rubber, like a rubber used for the cover stamp. The ink used is similar to gravure printing in that it has high volatility and thinness and is used for printing 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 plastic heating pressure on the above-mentioned electrotype, printed hard plate of the negative plate. Third, the same negative mold is heated and pressed on the female mold with another soft gel to obtain an offset printing plate which is the same as the original electric plate in the first step.
Various types of adhesive paper, such as Cellephane, P, V, C glue, Polyester paper, Acetate paper, etc., can be printed on the surface of the material without absorption and permeation ink properties. Applicable to plastic bags, hand pumping, size plastic packaging. However, this method of printing prints finer dots and lines than kosher and letterpress printing, so pictures should be emphasized with great effects.
Basic principles of lithography
Lithographic printing was developed and named after an early lithographic printing. The early lithographic printing was applied after the plate was polished and then modified to a metal zinc plate or aluminum plate, but the principle was unchanged.
Where there is no difference between the printed and non-printed parts, that is, they are flat, the oil-and-oil-independent mixing principle keeps the printed part of the grease-rich film, while the non-imprinted part of the layout can be absorbed. With appropriate moisture, it is assumed that after the ink on the plate, the printed part will repel moisture and absorb the ink, while the non-printed part will absorb moisture to form the anti-ink effect. The method of printing by this method is called â€œlithographyâ€. ".
After the lithography was developed from 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. Therefore, it was continuously researched and improved by experts in modern times and became the most used in printing today. Methods.
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 with a positive pattern. Due to the pressure exerted by this method during printing, the lithographic plate (that is, both the imprinted portion and the non-imprinted portion) is originally a flat surface, and after the pressure is applied, the ink occupying the plate surface is diffused. Inflated, resulting in poor line drawing, so later on it was called "offset printing" (offset printing). The printing method was to make the layout into a positive pattern, and when printing, it was transferred to a rubber tube for anti-patterning. Anti-printing is positive on the paper, so that the elasticity of the printing pressure can be improved.
The early lithographic printing was lithographic flat pressing. Later it was developed into flat lithographic circular presses and round presses. The lithographic rotary presses were mostly used for special printing, such as proofing machines for proofing purposes. Machines such as printing paper are all improved round-circular presses. The lithographic circular press type is also the flat layout of the printing plate, and the pressure part is a cylinder type cylinder. This printing method is similar to the lithographic rotary press machine in relief printing. Round-circular press type refers to the printing plate wrapped on the drum as the drum, the other drum on the machine is called the rubber drum, and the pressure part is the roller type drum. The constructed machine 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 quantities of printing.
2 Disadvantages: Due to the effect of water glue during printing, the reproduction of the color tone is reduced and the brightness is lacking. The layout ink is thin (only 70% of the capacity can be expressed, so the offset-style light box poster must be double-sided printing to enhance its color). Special printing applications are limited.
1 poster, 2 simple prices, 3 manuals, 4 newspapers, 5 packages, 6 books, 7 magazines, 8 monthly calendars, 9 other related color printing and a large number of printed materials.
The basic principle of gravure printing
There are many differences between the printed and non-printed parts, which is the opposite of the letterpress. That is, the part where the printing ink is printed is clearly recessed under the layout, and the non-printed part is smooth and glossy. When printing, the ink needs to be rolled on the plate first, then the ink naturally falls into the embossed portion of the depression, and then the surface-adhering ink is wiped cleanly (of course, the embossed ink of the depression is not erased). After the paper is put again, a large amount of pressure is used to imprint the recessed printing ink on the paper. Those who use this printing method are called "gravure printing."
Due to the heavy printing pressure in the gravure printing method, printing is performed with more than the letterpress or lithographic printing, and the pressure on the printing surface must be paid special attention. The printing method is the pattern anti-pattern, and the printing paper is a positive pattern.
Gravure printing is divided into engraving gravure and gravure
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 performance.
The copperplate printing paper used for engraving gravure is first moistened in the early stage, mainly to increase the cohesion of the ink. Therefore, a thick cloth should be laid on the back of the paper, and the pressure can be applied to the inside of the depression. The sticky ink is drawn onto the paper and printed on the paper. The main disadvantage of this printing method is that it needs to be dried after printing, which will cause irregular stretching and make the printed products have different lengths and lengths.
However, nowadays, the copper plate printing has been improved to a dry printing method to improve the plateau and make the lines of the engraving depression shallower. Make it easy to pull the ink sticky. According to the copper plate printing and steel plate printing, the depth of the pattern screen is based on the thickness and depth of the lines to express the three-dimensional sense. The thick and deep lines of the printing plate have thicker inks, so its ink color is more deep. Thin, thin plates have a thin, sticky ink, so their ink color is lighter. This type of print is as beautiful as the modern visual art design, but most of it is used to represent patterns or text, and it is more difficult to achieve continuous-tone like photos.
Photogravure, also known as photocopying, uses the principle of photography to corrode the copper plate, which is exposed by a light-saturated potassium dichromate solution (Larbo Tissue) and a gravure-dedicated screen plate. Then the adhesive tape and the continuous version of the positive film are printed. After the adhesive film is exposed twice, it can be developed by warm water. The adhesive film on the screen light part is lighter than the black and silver on the positive film. The degree of hardened by light waves is higher, so the film after water development is thicker, and the adhesive film on the dark part of the screen is affected by the thicker black and silver masking of the positive film, so the adhesive paper can be light wave. The degree of hardening by transmission is less, so the film developed after water is thinner. Therefore, the developed adhesive tape is thick and thin. It is attached to a copper roller or a flat roller. It is etched with ferric chloride. The thicker part of the optical part of the film can penetrate and erode the depth of the copper plate. Shallow, so its sticky ink film is thinner, then its ink is printed lighter, as dark film film thinner place, the glue thickness can solution penetration and corrosion into the copper plate must be deeper, so its imprint adhesion The ink film is thicker and the darker ink is printed.
Gravure printing advantages and disadvantages
1 Advantages: The ink has a performance of about 90%, and the color tone is rich. Strong color reproduction. Strong layout. The number of prints is huge. There is a wide range of paper applications, and 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 and gravure printing, because of its exquisite lines and not easy to counterfeit, are used in the printing of securities, such as banknotes, stock certificates, gift certificates, stamps, and certificates of commercial credibility or stationery. 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 prints. Generally, photogravure is generally used in a large number of printed materials, such as color magazines and currently popular building materials printing, etc. Are very suitable. Due to the use of high-speed rotary machines, gravure printing is not only fast but also print ink film thicker than letterpress or lithography.
The basic principle of stencil printing
In addition to the three editions of letterpress, lithography, and gravure, another kind of stencil printing similar to handicrafts also accounts for the uniqueness of the modern printing industry. Due to the influence of the modern business community, it has also received great attention in the design community. Because of its unique expressive power, stencil printing has a wide range of applications. It is a designer or general public. It is also necessary to understand the concept. Any part of the imprinted part is like a hole, and those who use this method are called "stencil printing".
Such as the general use of steel needles on wax paper or mimeograph printing with electronic corrosion, this is a more basic stencil printing, and in the design or industrial application of screen printing (ScreenPrinting), early screen printing is used in Handicrafts and the like have now been developed into automated printing, and in the area of â€‹â€‹plate making, photolithography has been used to make the layout; because of its strong ink color, there is a special feeling and it is most suitable for special effects.
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