Color glaze printing technology

Second, ceramic decal paper printing process

Since the color development of the ceramic color frit is different from that of the ordinary color printing, the printing ink can only print one hue. Therefore, manuscripts such as landscape flowers and figure characters on the ceramic are rarely used. The natural color continuously adjusts the photo, but the painter draws the original by hand. The pattern is mostly lines and color blocks, and the contours and edges are clearly “braked”. Since lines and color patches do not have continuous changes in color and gradation, they are generally not used in the process of plate making. When faced with an individual place that needs to show changes in the depth of color, the method of drawing by hand is used. Dark spots are spotted more densely, and lighter spots are painted sparsely. This is also the difference between ceramic decal printing and ordinary color printing.

1. Gravure decals Gravure decals are a printing technique that is older than lithographs. Earlier underglazes used gravure decals. There are fewer types of coloring material under the glaze, mainly cobalt oxide cobalt, and other color materials are properly deployed, showing a blue tone, mostly for monochrome printing.

The pigment is made into water-based ink with the binder, printed on a thin cotton paper with a gravure, and the printing ink surface of the tissue paper is pasted on the unglazed porcelain blank, and the water is applied from the back of the tissue paper, so that the ink is transferred and absorbed. The porcelain blank is then glazed and baked into the kiln. After firing at 1250-1300°C, the cotton paper is completely carbonized and burned, and becomes gas. The pigment is integrated with the ceramic and shows a blue-blue pattern. This is the underglaze color blue and white porcelain. Although this kind of gravure decal paper is monotonous in color, the pigment does not contain lead and it is harmless under the glaze. Therefore, underglazed blue and white porcelain has always been loved by people.

2. Lithographic decals Before the 1960s, there were few Chinese typographical machines. In lithographic printing, lithographs also accounted for a certain amount. Therefore, decals printing has always been based on lithographs. Why use lithographs? Compared to gravure, lithographs have the following two advantages: First, they are hand-painted on the lithographs and multi-color printing is more convenient than the gravure multi-color printing; the second is lithographic printing. The cost of printing is lower than gravure.

The stencil layout is first polished and cleaned, and the color pattern patterns are drawn manually on the lithograph according to the characteristics of the ceramic pigments after baking. The substrate is a layer of 30 gm paper on a 180 gm thick paper base. A layer of glue is applied to the thin paper, and the pattern is printed on the thin paper after the glue has dried. Due to the coarse and specific gravity of the ceramic pigments, it is difficult to roll the ink into lithographic inks. Therefore, the lithographic ink is actually a binder free from ceramic pigments. After printing all the water, after imprinting, dry the paint immediately and spread the pigment powder on the blot so that the pigment particles stick to the pattern prints, commonly known as powder. After the first color printing ink is completely dried, the second color printing is performed, and the like is repeated until the multi-color overprinting is completed.

Although lithographs have progressed compared with gravure printing, lithographic printing machinery has in fact been unwieldy, labor-intensive, and inefficient. A lithographic printing machine produces about 1,000 cigarettes a day, which is not as good as the output of typographers for an hour. Since the 1960s, with the development of plain printing, decal paper printing has gradually shifted from lithographic printing to plain printing.

3. Indirect plain printing decals Lithography and plain printing are both lithographic. The principle of printing is the same, but lithographic printing is semi-manual semi-mechanical and direct printing; plain printing is mechanized indirect printing.

In the early days of lithograph printing and plain printing, the production process of first printing and standing water was still used. Postpress tincture is not only inefficient but even more serious is the health of workers. From the 1970s onwards, in order to reduce the powder, dark-colored powders were used and light-colored inks were printed. As already mentioned, the ceramic pigments are all metal oxides, with coarse particles, a hard texture, and a large specific gravity. Printing by offset printing is based on the principle of incompatibility between oil and water. Although these metal oxides are mixed in the ink as a pigment, the printability is poor. Once water is encountered, the pigment is easily hydrated and destroyed. The balance of oil and water in the printing process. Therefore, in the process of printing on ceramics, whether it is the first printing of nitriding water, or the mixing of pigments with regular water, it is not an ideal solution.

For the problem of offset printing decals, improvement was made on the link material. The linking material for early printing inks has been refined from vegetable oil (ie, linseed oil). With the development of the ink industry, the amount of synthetic resin binders used to replace vegetable oils with synthetic resins is increasing. At the end of the 1970s, flat-printing decal resin inks that were rolled with ceramic pigments and resins were developed. The ink binder has obvious improvement on the pigment adhesion performance, less ash residue during roasting, stable color burning performance, bright glaze, and further improvement of the decorative effect of the ceramic. What's more important is that the resin ink does not need to add dry oil to reduce the lead content in the ink and is beneficial to human health.

Due to the widespread use of plain-printing ceramic pigmented resin inks, plain-printing ceramic decals printing has gradually eliminated the backward process of silicon powder, which not only improves the production efficiency but also improves the working conditions of workers.

4. Screen Printing Decal Paper In the 1950s and 1960s, foreign countries had used screen printing decals. Jingdezhen ceramic decal paper printing factory also tried screen printing decals at that time, but because the screen printing technology was still low at that time, Out of the pattern is too rough, so screen printing has not been widely adopted.

However, screen printing has certain advantages over plain printing and gravure printing. First, screen printing has lower requirements for printing inks, and there is no need to worry about the problem of ink hydration in the printing process. Second, the screen printing ink layer Thick, help to improve the decorative effect of glaze.

Since the 1970s, with the advancement of screen printing technology, the supply of screen printing equipment has improved, and the ratio of screen printing production of ceramic decals has gradually increased, while the ratio of plain printing production has gradually decreased. After entering the 1990s, major domestic ceramic decal paper printing plants have also gradually shifted to screen printing.

The key factor determining the fineness of screen printing products is the height of the screen mesh. In the past, people thought that screen printing products were rough, mainly because of the low mesh screen size (100 to 200 mesh). Since the 1980s, the fully automatic roller screen printers and 250-400 mesh screens have improved the physical conditions of screen printing. Ordinary products use 250-350 mesh inch mesh, fine products can use 300-400 mesh inch fine mesh. In the past, decal paper printing was mostly lines, text, or color blocks. There was little application of net technology. After fine mesh materials were used, 100-inch dot screen printing was also available on the screen, as long as the number of screens and wires was satisfied. The ratio of the number of meshes is 1:3. That is, when the number of meshes of the screen is 300 meshes, using this screen mesh for screen printing, the number of lines crossing the screen may be 100 lines/inch.