1. Overview

Silk screen printing, also known as silk screen printing, is commonly known as silk screen printing. Its basic principle is Stencil. Its origins, like the woodblock prints, can be traced back to the distant past, even to prehistoric cultures. According to literature records, primitive people in ancient times used the spray method to print human hand shapes on stone walls (Figure 288a). This can be called the primitive and earliest perforation technique.

my country is the first country to apply perforated printing technology in the printing and dyeing industry. According to records, during the Daye period of the Sui Dynasty (AD 605-616), the clothes and dresses used in the palace were printed and dyed with Loukengban (clip payment). As time went by, this printing and dyeing technique, which was initially only available to rulers, gradually spread to the people. During the Ming and Qing Dynasties, this printing and dyeing technology was popularized throughout the country, and finally formed perforated blue printed cloth with rich national artistic characteristics (see the section on paper perforated printing). Around the twelfth century AD, this hole-blocking technique was introduced to Japan from China and further developed in Japan. As we all know, when engraving perforated plates, a common problem is that each "shape" (called "island") must be connected with a "bridge" (as shown in Figure 288), otherwise each shape will not be connected together. Become a page. The appropriate location for this "bridge" has a lot to do with the aesthetics of the hole pattern. "Building bridges" was called "breaking joints" in ancient China. Later, the Japanese replaced this "bridge" (or "knot") with hair or silk thread. In this way, the hair and silk threads are almost unaffected when scraping and printing. Today's silk screen technique can be said to have been produced on the basis of this method. Silk screen is used as a plate material. The blocked part of the mesh is the "island" and the exposed mesh part is the "bridge" (Figure 289)

Figure 288 shows the principle of the hole plate. Figure 288a Prehistoric human handprints on the cave wall (negative picture) about 1585 BC

Figure 289 Diagram of the principle of wire mesh leakage

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Figure 290 B. Xie An's "That's All Beautiful" 1965 silkscreen (76x117)

In the West, perforation printing has been used in commercial and decorative crafts for a long time. Such as billboards, fabric printing and dyeing, spray printing on walls and some utensils, etc. Sometimes this method is also used to print velvet paintings and the production of art work by students in schools. At the beginning of this century, Englishman Samuel Simon developed silk screen printing and kept it secret for several years (1907-1915). Later, due to the special needs of the military industry, this technology was patented in the United Kingdom and the United States. However, artists and printmakers did not take it seriously. They did not have the same enthusiasm as earlier artists for woodcuts, mezzotints and lithographs. Instead, they avoided and rejected it. One of the important reasons is that some printmaking institutions and award panels often exclude silkscreen prints from art exhibitions on the grounds that they are vulgar. The 1930s was the most depressed period in the United States. Thanks to the efforts of the Art Planning Department of the Federal Work Development Agency, a group of artists headed by Anthony and Velonis were prompted to use silk screens to practice artistic purposes. . Compared with copper and stone tablets, a complete set of wire mesh equipment can be built at a relatively low cost. This advantage is extremely beneficial in the United States during difficult times.

For this reason, in the 1930s, there were some outstanding artists in the United States, such as Ben Shahan, Robert Gwathmey, Harry Sternberg and others. Only some artists with a social conscience transferred their talents to the practice of silk screen printing, and used their creations to re-evaluate silk screen art, a method that had been abused for commercial purposes.

The special pursuit of screen printing in art has greatly improved its status in the art world and people's prejudices against it, allowing it to develop and influence a group of artists in the 1950s. . They include abstract expressionists and action painters, such as Jackson Pollock, Marcel Duchamp, etc.

From the late 1950s to the early 1960s, due to the Pop Art movement and the application of photoengraving driven by new concepts, screen printing was generally recognized and loved, and was labeled as avant-garde. A good name for the medium. In pop art, such as "found object" (Found object), "light effect art" (Opart), "hard-edge" (hard-edge), "stripe" (Stripe), "color" ( Color field) and "Sign" paintings (Sign paintings), etc. They are all devoted to silk screen printing, using the most popular media as creative raw materials, and adopting the art collage method to express their works. At the same time, because the screen printing plate can be adapted to printing on three-dimensional objects, it breaks the established boundaries between painting, sculpture and printmaking. In this movement, famous artists include: Pop artists Robert Roushenberg, James Rosenquist, Andy Warhol and Roy Leake. Roy lichtenstein et al.

Due to the development of economy and technology, the application of nylon or stainless steel wire mesh, and the improvement of power systems, it is possible to produce and copy the "original work" hundreds of times, thus affecting the screen printing The value and reputation of prints. In addition, since most of these silk screen printmakers do not produce their own works themselves, but hand over their drawings to silk screen printing masters for printing, this has given rise to controversy over whether they are "original works". Since there were thousands of copies, the author was unable to sign and inscribe them one by one, thus increasing suspicion about it. This is an important reason why the price of screen prints in the West has always lagged behind other types of paintings. Other printing types have had precedents of division of labor between painters and technicians in the past, but that is the reason why printmaking is a tool of the printing industry. Nowadays, the division of labor between artists and technicians such as screen printing and other types of printing has become a means of profit-making, which cannot help but devalue printmaking. Of course, it is not impossible that it has become popular all over the world as a cheap medium for the masses.

The rise of screen printing as a form of printmaking in my country is only in recent years. However, as an industrial screen printing, it has long been very common in my country, such as trademarks, advertisements and printing and dyeing factories. Textile printing and so on. However, since there is currently almost no printmaking market in China, the development of this kind of screen printing that is convenient for mass production still needs to wait for the economic development and the improvement of material and cultural living standards.

2. Equipment and materials

The equipment for screen printing is very simple. The most basic one is: a wooden frame with a screen (i.e. a screen frame) with a dumpling chain on one side. It is the same as a squeegee when connected to a platen.

A. Wire mesh:

Initially, silk mesh was used as the mesh, and later developed into nylon, synthetic fiber mesh, stainless steel mesh, etc. At present, silk screens are widely used in industry, but only a few are used by artists to make prints.

Generally, we use synthetic fiber mesh as the most affordable option. This kind of mesh is sold in major department stores. You should be selective when purchasing. Generally used for printmaking, it is appropriate to choose about 150 mesh (mesh, that is, the number of meshes per square hour.)

B. Screen frame:

Generally, it is straight and not easy to deform. The wood is better made, such as pine, fir and other woods. The size of the wooden strips used is 4 × 5 centimeters, and can be increased or decreased appropriately according to the size of the net bars. The structure of the wooden frame is shown in the figure. It should be aimed at firmness and fairness.

C. Netting method:

Generally, a stapler can be used to nail the net to the bottom wooden strips. When nailing the mesh, pay attention to the straightness of the longitude and latitude lines of the mesh. The net can be tightened and nailed in several ways as shown in Figure (292). After the screen frame is nailed, the four sides (including the inside and outside) must be sealed with wide tape (as shown in Figure 295) before it can be used for plate making and printing. In this way, when scraping and printing, the edge of the painting will be straight and clean, which will also make it easier to clean and reuse the screen frame.

D. Fixing method of screen frame and platen:

The simplest method is to use door and window hinges that can be twitched by a shaft rod to connect them. For example, when opening and closing doors and windows, when the hinge shaft is pulled out It can be separated from the table when using the stick. Another method is also very convenient (Figure 296). There are many ways to do it, but in short, the purpose is to be able to open and close when the two are connected and to facilitate disassembly for plate making and cleaning.

E. Squeegee:

It is the main printing tool for screen printing. The scraper can be made with a mortar: Use a wooden board (three-ply or five-ply) to clamp one side of an oil-resistant rubber strip with a thickness of about one centimeter and nail it firmly. (Figure 294) The size of the scraper should be slightly shorter than the short side of the screen frame (because it must be scraped from top to bottom when scraping). The head of the scraper strip needs to be ground straight with iron sand. Do not bevel or round. (Figure 294)

3. Production method

The production of screen printing can be roughly divided into three categories: one is the hole engraving method, the other is the direct painting method, and the third is photography Photosensitivity method. However, no matter which method is used, there is only one basic principle, which is to try to block or leave holes in the mesh according to the drawing or idea, so that the paint can leak through the mesh and fall on the printing surface, which is the pattern the author needs.

A. Knift - cut stencils:

Lacquer Stencil Film, a kind of stencil paper specially used in the screen printing industry, is made with sulfuric acid. Paper or polyester sheet is a paper-based soft varnished film paper. You can also use copy paper to flatten a layer of varnished and make your own. Use a white knife to gently carve various patterns on one side of the paint film (be careful not to scratch the paper base), and then use the tip of the knife to gently pick off the carved paint film. The removed part is the missing pigment part. After engraving, place the silk screen on it (pay attention to the alignment position), then use gauze dipped in banana water to lightly wipe it on the screen, and dry it with clean gauze while pressing it tightly to adhere all the desired paint film graphics to the screen. Net bottom. After half an hour, the paper base can be peeled off, and the plate making is completed (the sealing process is very similar to this method). The perforated method is a traditional method for screen printing. In the section on paper printing, the perforated paper printing method mentioned uses thick paper to engrave holes and directly print the prints. For example, you can use thin and tough paper to carve various patterns and stick it under the screen with glue or ink to achieve the purpose of screen printing.

Figure 299 Use a bucket scraper to apply photosensitive adhesive on the net

B. Direct coating method:

How many materials are used to seal the net? Such as glue, wax paint (clear spray paint), gouache, shellac paint (also known as dry paint, soluble in alcohol) and medicinal ink (or thin ink), etc. Some of these materials are soluble in water, while others are waterproof... Knowing these, you can freely use different plate making methods.

Example: Use glue (or glue plus gouache) to paint on the net. After it dries, brush the entire net with shellac paint. After it dries, wash off the glue part with warm water. That's it. On the contrary, if you use shellac paint to paint on the screen, then use glue to brush it after it dries, and then use alcohol to wash off the shellac paint, you can also make a screen in the same way. This plate-making technique of interchangeable front and back is also similar in lithographic and gravure techniques, and can be used as a reference for each other.

This method can also be used to make layouts using wax and medicinal ink, crayons and glue, etc. However, one thing must be noted: for screens made with glue to seal the screen, the pigments used for printing can only be oil-based. Printing with water-based pigments will wash away the glue that seals the screen. In addition, in order to prevent the glue from cracking after it dries, you can add a little syrup and a few drops of glycerin. This is the same principle as the sugar-water method of copper engraving and the glue-draining method of single-frame printing.

In addition, there is a wax-wiping direct coating method, which is like the physical rubbing printing method (see physical printmaking). That is, use crayons to rub against various physical textures placed under the net, then brush them with glue, and use gasoline to wash away the crayons. Then you can get screens with different textures or various physical objects.

C. Photographic sensitivity method:

Use a bucket to scrape (see Figures 298 and 299) to apply the photosensitive emulsion flatly on the net and then mix it with the black and white artwork (or use a photographic film ) The film is closely attached and exposed. After exposure, the emulsion hardens and fixes the screen, sealing the mesh. The non-photosensitive part can be washed away by water to expose the mesh. This is the basic principle of photographic sensitization, which is the same as the photographic platemaking methods of convex, concave and lithographic plates. For details, please see the section of photolithographic platemaking.

(Figure 300-1-8)

Figure 300 Photosensitive screen production process

Figure 301 Diagram of the two methods of photographic screen photosensitization, sunlight printing and light printing

4. Printing

Compared with other types of printing, the scratch printing of silk screen printing is simple and quick. Use a scraper to scrape the printing material evenly from top to bottom. When scraping and printing, there should be a slight gap between the screen and the paper platen, so that when scraping and printing, the screen will automatically bounce up after the scraper passes, and the paint missed on the paper will not overflow the graphic boundary.

Screen printing pigments are currently not sold in China specifically for printmakers. Therefore, painting pigments and printing inks are mostly used, but they must be prepared before they can be used. Oil paints and inks need to be thinned with mixing oil or turpentine. Water-based pigments need to be mixed with glue or paste. Silk paint, which was commonly used commercially in the past for printing thick paint, can also be used to print prints and has a sense of thickness.

In order to ensure that each print is printed in the center of the drawing paper, you can use cardboard to make positioning marks on the table below the screen.

The color registration method is the same as other plate types, but the plate alignment method can use transparent polyester sheets to adjust the position, which is accurate and simple. The method is: place the polyester piece under the net, with one side fixed to the platen with tape, and then scrape and print the master plate on the polyester piece. When overprinting, just place the printing paper under the polyester sheet and align it with the main pattern, then lift the polyester sheet aside to remove the screen frame for scraping printing. In addition, cross marks, corner marks, etc. can be used.

If the printed screen needs to be retained, the mesh covered by the paint should be washed with water or kerosene to prepare for printing next time. After printing with oily pigments, you can use kerosene (or gasoline) to clean it. When scrubbing, some old newspapers must be placed under the net to absorb the ink washed off the net. Water-based paints can be rinsed with water. If the post-printing screen is not retained, you can use industrial bleaching powder to make a paste and apply it on the screen. After half an hour, scrub it with a steel brush, and then rinse it with water. Another method is to use caustic soda solution (50 grams of sodium hydroxide, dissolved in 300 ml of hot water), wear acid-proof and alkali-proof rubber gloves, use stainless steel clamps to hold cotton dipped in the caustic soda solution to scrub the entire network. After about half an hour, that is Rinse clean with water.