Simulation Of Wax-Printing Patterns And Its Application In Inkjet Printing

Wax-printed fabric with a long history has its unique ethnic style. It has been found in China, India, Japan, Southeast Asia and Africa from over 2000 years ago. Its greatest charms and characteristics mainly lie on the crack patterns generated from the process of the natural cracking.With the diversity of textile styles, wax-printed fabric is very popular in the international market. Due to the extremely low productivity of the handmade wax-printing, the industrial imitating wax-printing emerges as the times required. The effect of the imitating wax-printing, to a great extent, is determined by the imitation effect of crack in the wax-printing pattern. The crack of handmade wax-printing is delicate, natural and full of gradation without fixed circulation units, while the imitating wax-printing by roller and screen printing is rigid, repeatedly permutated and has fixed patterns.This paper presents the textile inkjet printing technology as a new technique to imitating wax-printing. The inkjet printing textile is vivid with high definition and fidelity, it can express the particular effects of the hand dyeing. The original file for inkjet printing requires digitalized pattern, one of the difficulties designers might encounter in the process of making digitalized wax-printing pattern is the crack simulation. Therefore, this research focuses on the computer simulation of wax crack and the inkjet printing process with imitating wax-printing pattern.Imitation of wax-printing pattern not only relates to the crack simulation, but also is combined with the digital inkjet printing technology. And design the new wax-printing styles to satisfy the requirements of modern esthetics. Eventually these patterns are able to be applied in clothing and home decoration effectively. For this purpose, this study analyzes the characteristics of handmade wax crack, and abstracts the artistic form into mathematic model. Meanwhile, it presents a simple and efficient new algorithm with advantages of the Distance Transformation and Voronoi diagram. It can generate authentic crack effects comparable with the handmade ones. Through the discussion on the specific process of imitating wax-printing using inkjet printing, it can be well applied for garments and other textile patterns. So the form of wax-printing style will be widely inherited and developed.The main content is as follows:(1) The paper gives a general review on the research status of imitated wax-printing as well as the method of computer simulate wax-printing pattern. Basically, imitated wax-printing pattern has clearly geographic and nationality, which make it full of variety. Subjects in an imitated wax-printing pattern can be various existences in nature or some abstract graphs. The imitated wax-printing pattern requires bright and dark colors to highlight the unique features of minorities. There are a lot of types of imitated wax crack pattern to make distinct designs. Generally, there are two different techniques of imitating wax-printing: direct printing and resist printing. In addition, screen printing is the major technique employed in direct printing which is the most frequently used nowadays. However, only few researches have been focused on simulating wax-printing pattern and most of designers choose to make hand drawn graph with graphic design software.(2) A thorough analysis is made about the characteristics of crack in handmade wax-printing. In the process of making handmade wax-printing, the shape of crack under nature cracking is affected mainly by the elements which are composition of the wax, the thickness of wax layer, fabrics, and dyeing temperature; Due to the difference in production, the thickness as well as the curvature of cracks are not the same and more thick lines often show up in the intersection areas. The form of wax cracking determines if the fabrics are nature cracked, parallel, or in the shape of a square. Besides, the sharp of crack is related to the pattern, the size of waxed area affects the direction of the crack generation. Moreover, the cracking extent and sequence could realize different dyeing and gradation of colors. In addition, there are blur-dyeing parts produced by wax not firmly stick to the fabric, which can be also regarded as one of the important characteristics of handmade wax-printing. By analyzing the crack feature, major shape and visual effect in patterns as well as color gradation, it provides theoretical foundation for computer simulation of wax-printing.(3) A method is presented to simulate wax crack pattern based on improved Distance Transformation algorithm. This improved algorithm is comprised of two parts: crack simulation and dyeing simulation. Firstly, the initial point positions are determined after executing distance transform on the original pattern, they will be distributed on the areas which have the largest distance values; and then the spreading direction is determined according to the gradient of distance transform. However, gradient direction is not the only one reference and the practical case also takes the dithering into consideration. In the form of Gaussian random noise, the dithering makes the crack more realistic as it adds a little angular deflection to crack. In addition,"age"is another factor which is created to show the thickness differentiation of new and old cracks. The property of hyperbola is taken use to achieve different boldness effect based on the analysis of cracks' intersection areas. The density and distribution character of crack are accomplished by adjusting the number of cracks and the random distributed function. In order to make the dyeing more flexible, the dyeing of crack is simulated by using Multiplicative Color Model.The advantage of improved Distance Transformation algorithm is that it can bring a controllable direction of crack generation. By ensuring that the crack spreads toward the edge of the waxed area, the simulated wax-printing pattern could be more realistic. However, the algorithm has limitations, such as unnatural line shape in certain condition. Additionally, for those cases that distance information is not necessary or crack is unrelated to the pattern, this method is not appropriate.(4) Based on the improved Distance Transformation algorithm, a new algorithm which employs the Voronoi diagram is proposed, so as to improve those issues which can not be solved when using Distance Transformation algorithm alone. Voronoi diagram provides a structure with a relatively symmetrical network which matches the crack properties in natural cracking, but it is difficult to control the distribution and spreading direction of cracks. This new algorithm combines the advantages of Voronoi diagram and Distance Transformation algorithm, it not only ensures that the simulated crack perpendicularly spread to the pattern edge, but also is consistent, flexible and able to simulate a variety of characteristics of cracks.Firstly, distance transform is made in digital wax-printing pattern and the Voronoi sites are required to be distributed randomly at places where the points have the largest distance values in the pattern; then, the original Voronoi diagram is obtained by Delaunay triangulation. Select the Voronoi boundaries in the pattern; Gaussian noise is added to the spreading directions of the new generated boundaries. Finally, the blur-dyeing effect is simulated in the non crack areas by using Perlin noise and the dyeing model is used to crack rendering to obtain the ultimate simulated cracks. The experiment results show that the new algorithm can imitate authentic wax cracks, even with some unique crack patterns, and the rendering image effects can be varied by parameter modification. For simulation of multi-color wax-printing pattern, it can render cracks to the pattern just like the procedure of handmade wax-printing.(5) The production design and application of digital wax-printing patterns are discussed by using advanced computer simulation technology. The design process of wax-printing pattern has been improved by combing science with arts, modern design with tradition. And through designing for specific applications in upholstery fabrics, garments and accessories, it can demonstrate the computer simulation effect of wax-printed product design. Additionally, such a new type of wax-printing pattern can be helpful to expanding the expression technique and application area. In the mean time, as well as create a new aesthetic style, it can add crack shapes, colors, lines to make up for the limitations of hand dyeing method, which would give an outstanding performance in modern textile design.(6) According to the existing problems of imitated wax-printing, a discussion is made on imitating the digital wax-printing pattern with inkjet printing technology. By pretreatment with applying quaternary ammonium salt based cationic modification agent on cotton fabric, inkjet printing is carried out with six kinds of pigment-based ink in 8 pass, 720 dpi to print color pieces, lines, and digital wax-printing patterns, and analyze the wax-printing pattern properties such as color yield, sharpness and color fastness.The results indicate that the inkjet printing effects of imiation wax-printing patterns on modified cotton fabrics have obviously improved compared with the untreated ones. It proves that the pretreatment of cationic modification agent enhances the dyeing performance of pigment ink on cotton fabric with a better depth and more sharpness. The pigment ink used in this experiment offers a washing fastness to Grade 4, but slightly lower rubbing fastness. Comparing the inkjet imitated wax-printed patterns with the handmade samples, the results show that the imitated wax patterns have an authentic effect as compared with the handmade ones, which exhibits an industrial prospect using inkjet printing to produce simulated wax-printing pattern, and it offers better crack effect and hand dyeing style. Based on the computer simulation and digital inkjet printing, it can be flexible to achieve a variety of requirements in wax-printing style, and it is closer to the art spirit of handmade wax-printed fabric.Using computer simulation and inkjet printing technology, it will substantially increase the efficiency of wax-printing pattern design and the imitating production, which makes it possible for massive customized costumes. Therefore, this marks the tendency of commercialization of imitated wax-printing products.