Discussion on improving the printing process of Jurassic printing
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With the continuous improvement of the cultural quality and economic income of the people, the collection fever continues to heat up, and more and more collectors have shown a strong interest in the reproduction of ancient Chinese paintings. People also have a new understanding of the collection of replicas: replicas also have a certain artistic appreciation value and potential economic value. For the above reasons, and because the keluo printing can maximize the artistic features of the originals and reach the artistic realm that other printing methods are difficult to achieve, it has attracted more and more attention from the industry.
First, the status quo and development trend of the printing
At present, most of the copied calligraphy and painting uses woodblock watermarking and photocopying, and the high-grade replicas are printed in the Jurassic version. In contrast, the woodblock watermarking cost is low, and it can duplicate the well-defined calligraphy and painting works. However, because the wood carving is entirely manual, the operator is required to have higher artistic accomplishment and excellent copying skills, and the original technique and brushstrokes should be fully expressed according to the ink painting method of the paintings and paintings. Generally, two sets of printing are required. The version can be well printed, although it is now possible to use a computer engraving machine to quickly and accurately produce woodblocks, but the application is rare.
Miluo printing is a kind of lithography, which is mostly used for the reproduction of ancient Tibetan paintings, calligraphy, monuments, and seals. The cost of printing with the 珂罗版 is relatively high. Its characteristic is that the level of shading is not based on the depth of the dots or the ink layer, but on the degree of exposure hardening of the stencil film. The degree of ink adhesion is proportional to it, similar to film. The silver salt exposure mechanism, so that the essence of the original paintings can be completely reproduced. In the reproduction of ancient paintings, paintings are embodied in colors and levels. Most of the printing editions use dots to express colors and levels, while the Jurassic printing does not. Its color and level are dependent on the density and the steps of the photosensitive film, that is, the ancient Jurassic copying process. It is irreplaceable by other editions, and its copying effect, appreciation value and commodity value are higher than other printed materials. The calligraphy and painting copied by the Jurassic method has become a highly tasteful art and collection in the people's life.
The Jurassic printing was invented by the German Albert in the 1860s. It was introduced to China from Japan in the early years of the Qing Dynasty. In 1876, Shanghai Zhengshou Bureau hired Japanese experts to successfully test the printing of the Jurassic, and then the Civilized Bookstore began to print. In 1907, the Commercial Press began experimenting with the technology of the Jurassic version. In 1919, it finally succeeded in printing 15 color overprints of rice paper, which was a milestone success. Since then, China's Luolu printing business has developed greatly. In the middle of the twentieth century, newer printing techniques appeared, and the printing of the Jurassic was once weak. Because the popularity of the printing process is not strong, the materials are not easy to buy, and the self-doped chromate photographic liquid is toxic, it is difficult to adapt to the shortcomings of individual investors, which seriously restricts its development. Due to the above reasons, many of China's Jurassic printing manufacturers have been revoked, and the Jurassic printing seems to have been forgotten. However, after all, the technology of the Jurassic version can not be replaced by other printing methods. Since the late 20th century, with the rising demand for high-quality replicas of ancient Chinese paintings, the technology of the Jurassic has been re-accepted by people. The printing process will enter a new development period like “Blood Tree Spring”. From the current cultural and art market in China, the transaction has begun to take shape and has a great growth momentum, as well as the printing industry is constantly appearing in the printing enterprises engaged in the reproduction of art, some printing companies copy the large amount of printed exports, etc. The printing process will be further developed.
Second, the characteristics of the print and the obstacles to its development
The characteristic of the keluo printing is that the gradation of the enamel is not achieved by the depth of the dots or the ink holes, but is achieved by different degrees of exposure hardening and different expansion properties. In the printing, different degrees of expansion of the film are used to absorb the unequal moisture to achieve different degrees of adhesion and repulsion to the ink, thereby reproducing the continuous level. This ancient method shows excellent tone reproducibility, and although the printing durability is low, it is this feature that has preserved the ancient methods to this day. As a copying process of copying Chinese painting, gouache, pencil drawing, copybook and black-and-white photographs, the Jurassic version has its unique place.
The characteristics of the Jurassic printing process are summarized as follows:
1 belongs to direct lithography. Milo printing is a kind of lithographic technology that was invented very early. It is different from the offset printing. There is no intermediate rubber roller to transfer the graphic, but the printing plate and the imprinting mechanism (imprint roller) are in direct contact for ink transfer. ;
2 application of photosensitive film expansion principle;
3 low printing resistance, generally only print 500 to 3000, up to 5000 or so;
4 The copying effect is good, and the level of the original can be faithfully reproduced. Different screens can duplicate the continuous tone image such as photos, and the copying effect far exceeds the lithographic offset printing;
5 The process is difficult and requires a group of staff with advanced technical level;
6 high cost and long printing time;
7 is used narrowly and is mainly used to copy classic manuscripts such as handwriting and painting.
Third, improve the efficiency of the printing process
Through the application of new technologies and the experience of long-term work, the following measures can be taken to improve the efficiency of the printing process:
1. Reasonable choice of film and shooting
The first step in the Milo printing process is photography. In the process of copying, taking pictures by camera is a method commonly used in the printing unit of the Jurassic printing to obtain printed film. This method can make the original layer and color vivid and realistic, and the loss rate of layer and color can be Artificial control is at a minimum. The film used in photography is roughly divided into two types, one is a hard film for writing, such as YZ-600II copy film, and the other is a full color film such as PA or PB film. Color pictures, according to the text, the film is divided into two types: box and roll.
When shooting various paintings with spot colors as the main color, its reflection of the hue and level directly affects the overall visual effect. A more concentrated spot color painting, if the tone is longer, you can take 3 prints to complete, that is, light gray, medium gray, black. Light gray can be taken with a PC film, which makes the overall tone longer and the particles of the basic tone are fine. The medium gray is shot with a neutral PB film, which has a certain sensibility of the photosensitive sheet and a clear color tone. The black version uses a PA film, which makes the dark parts of the painting rich in layers and suitable in tone. In the filming of Mr. Xu Beihong's works, "Jiangjiang Chunyu", "Running Horse" (Fig. 1) and Mr. Wu Zuoren's "Camel", Mr. Qi Baishi's "Shrimp", Mr. Huang Wei's "驴" is a monotone-based level. This method has been adopted for a wealth of works, and its effect has been very successful.
2. Correctly apply the combined solution and the photosensitive liquid
The bonding solution should be poured on the frosted surface of the glass. When pouring, pay attention to the first solution. Pour the bonding solution on the A end of the glass, then lift the A end of the glass with the left hand, and hold a bow in the right hand. Combine the liquid and let it flow to the B end one by one, as shown in Figure 2. When the entire glass surface is covered with the binding liquid, put it on the bracket, free your hands, and then lift the glass off the bracket from the two side ends of C and D, then shake the front, back, left and right to make the combination. The liquid is evenly spread over the frosted surface of the glass. After drying, a layer of photosensitive liquid is applied to the binding solution by the same method (Fig. 3). When the coating is uniform, the shaking is stopped, and then the glass plate is placed on the drying rack to be naturally dried.
3. Improve the printing process
We know that the principle of all photohardening is as follows: a kind of organic substance dissolved in water and swellable, treated with dichromate to make it photosensitive, and then dried, exposed and developed, the unexposed part is The unhardened portion and the exposed portion are hardened portions. In order to make the hardened portion stronger, a light return process is required. In the subsequent printing process, the hardened portion, that is, the image portion is inked, and the unhardened portion is not inked, thus highlighting the graphic portion. When printing the plate, first place the photosensitive glass on the platform of the printing machine, the photosensitive adhesive surface is facing up, and then put the modified bottom plate, so that the graphic part is exposed, and the surrounding is covered with black paper to prevent the non-graphic part of the layout. Exposure, otherwise it will be inked when printing, causing pollution of the picture. The exposure time can be adjusted at any time depending on the picture. Another point to keep in mind is the orientation of the bottom plate. Since the bottom plate is a negative film, the bottom plate should be placed on the photosensitive plate in the opposite direction to the original, that is, the text or graphics on the left side of the original should be placed on the right side on the photosensitive plate. Only then will it be restored from the right to the left after printing on paper. After each version is finished, the "back light" is taken, that is, the bottom plate is removed, and the photosensitive plate is turned over, with the back side facing up, the photosensitive surface facing down, and then exposed. The purpose of this is to make the graphic part solidify more firmly. After the positive and negative exposures are completed, the photosensitive plate is placed in the sink for washing.
4. Reasonably adjust printing pressure
Due to the flat printing technology, the printing of the keluo has always had the disadvantage of insufficient printing pressure. In recent years, this situation has been improved. People have introduced the proofing machine into the Jurassic printing. Through a series of debugging and modification, the proofing machine has become a large-format Jurassic printing machine, which solves the problem of large-size printed matter. Needs, but also overcome the shortcomings of manual operation pressure is sometimes not enough, it can be said that it is two birds with one stone.
The proofing machine is very convenient for printing. When the button is pressed, the machine automatically moves forward. When the cylinder is pressed, the pressure is transmitted, and the ink on the printing plate is transferred to the substrate. However, the size of the pressure is critical. If the pressure is too high, the plate glass will be crushed. If the pressure is small, the ink cannot be completely transferred to the substrate. Therefore, it is extremely important to adjust the pressure. The usual method is to add some hard cardboard to the substrate (such as rice paper), add a layer first, try it, if not enough, add another layer until it is suitable. At the same time, it is emphasized that the width of the hard cardboard is preferably the same as the width of the printing plate. If it is narrow, it is easy to cause damage to the printing plate.
Fourth, the problems and solutions for the printing of the keluo
1. The color is not allowed
Color registration is not affected by the temperature and humidity of the paper, resulting in shrinkage or expansion, conditional printing units, to strictly control the indoor temperature and humidity, temperature control at 18 ~ 22 ° C, humidity control at 70% is good.
2. The plate is dirty
The reason for this is that the printing plate is made with a plate with a relatively high humidity. The overprinting is too long and the photographic adhesive is not well filtered. The granules are too thick. The plate used on the same day can be soaked in water and then covered with a glass plate. Stay in the printing plate and use it after 12 hours. If it is dirty, you can take the decontamination water diluted 1:2 to get dirty. If the effect is still not good, you can use pure ammonia water to get dirty.
3. Xuan paper adhesion problem
The causes are: the film is not enough, the film is soft, the rinse time is short when the plate is made, and the film is still not in the photosensitive part. The solution is to overcome it with a light film or a formalin.