The Chinese people's use of indigo grass pigments for dyeing can be traced back to the Spring and Autumn Period and the Warring States Period. Xunzi, a great thinker in the late Warring States Period, witnessed the pigment transformation process of green "blue grass" and the process of dyeing it from yellow to green, from green to blue, and then to blue again, and said "green is taken from blue, and green is derived from blue." This exclamation has become an eternal saying to describe the superiority of future generations over their predecessors: "The youth is better than the blue." Indigo dye developed into the technique of indigo dyeing, and the dyed colors such as indigo and cyan are also the main colors of traditional Chinese clothing.

The "Essential Art of Qi Min: Planting Blue" written by Jia Sixie of the Northern Wei Dynasty specifically describes the method of gathering blue lake from blue grass: "Make a pit in the middle of July, make a hundred bundles, and make wheat straw mud." Make it five inches deep with mud and cover the four walls with thatch. Place the cuttings upside down in the pit, put them into the water, and cover them with wood and stones. Let them stay for one night when it is hot and again when they are cold. Then drain off the water and put the juice in the urn. Take ten stone jars, put a bucket of five liters of lime into it, throw it down with your hands, and let the water drain away after eating. Make a small pit, and store the blue water in the pit until it is like strong porridge. "The lake is ready." This is the earliest record of the blue lake-making process in the world. The dye of blue calico is based on indigo grass. Indigo grass is mainly divided into four types according to the characteristics of its family and growth environment, namely polygonum indigo, mountain indigo, wood indigo and woad. Jiangsu is famous for its abundance of indigo; Zhejiang, Fujian, Yunnan, and Guizhou are suitable for planting indigo; Shandong and Hubei are suitable for planting indigo and woad; Taiwan mainly grows indigo and mountain indigo. At that time, people used indigo to process indigo, mainly for dyeing blue cloth (pure blue cloth), and also for dyeing twisted and clamped valerian.

Ancient anti-slurry printing has a long history. As early as the Northern Dynasties, white floral cloth with a blue background using hollow patterns and dye resists appeared (a fragment of white floral cloth with a blue background was unearthed from the Northern Dynasties ruins of the Yulaike ancient city in Yutianwu, Xinjiang). The pattern was composed of large and small dots, but the dots were different from each other. It is connected, and there is a phenomenon of connecting patterns, and it was originally called wax valerian. After it became popular in the Tang Dynasty, it was collectively called dyeing valerian.

It also includes twisting and clamping. The clamping process is made by carving strands of specific wooden boards. Then the cloth is folded in half and sandwiched between two wooden boards with the same pattern. After bundling, the required color or color is injected. Put it into the dyeing vat for dyeing. After the splint is removed, the blue background and white flower pattern will appear. Because the valerian clamping process is relatively complex, the engraved pattern is time-consuming and easily deformed. In the Southern Song Dynasty, some people improved this method and used it for printing and dyeing blue cloth, also known as "medicated cloth". According to the "Ancient and Modern Books Collection? Zhi Fang Dian" records: "Yaobanbu came out of Jiading and Anting Town. In the middle of Jiading in the Song Dynasty (1208-1224 AD), someone with the surname Gui created it. The cloth was plastered with medicine and dyed. After drying, remove the gray medicine, and it will appear green and white, which can be used as quilt cover and curtain. The pattern is composed of large and small spots. These spots can prevent the cloth from being dyed blue and keep the white color of the gray cloth, so it is called "medicated spot cloth" and commonly known as watering flower cloth.

Huang Daopo, a female textile technology expert from the Yuan Dynasty, was a native of Wuni Town, Songjiang, Jiangsu Province (which was transferred to Shanghai in 1958). She was a child bride when she was a child. Unable to endure the abuse of her feudal family, she fled to Yazhou. After living in Hainan for 30 years, I learned the textile technology of the Li people. After returning to my hometown, I introduced the textile tools of the Li people and improved them to make a complete set of production tools such as weaving, elastic, spinning and weaving. Textile technologies such as flowers have promoted the development of the cotton spinning industry in Songjiang area. After the Yuan and Ming Dynasties, cotton was widely cultivated and "spun into yarn and weaved into cloth". Spinning and weaving in Songjiang and Nantong areas has become "a habit and a permanent industry for every household". In the middle of the Ming Dynasty, it had developed into a distribution center for cotton textiles. The area was close to the river and the sea, and the soil and climate were suitable for cotton cultivation. The cotton produced was not only large in quantity but also of good texture, providing good conditions for the development of the handmade textile industry. Farmers in this area use this as a side job. The cloth they produce not only meets their daily needs, but is also sold to all parts of the country, Japan and Europe.

With the development of cotton spinning handicraft industry, cotton cloth has become quite popular among the people and has become the main daily necessities of farmers. Indigo grass was planted in large quantities, and dyeing workshops increased one after another. People's demands for daily necessities continued to increase. The simple and rough graphics of the original "medicated cloth" could no longer meet the people's aesthetic and life needs. Folk artists boldly absorbed paper-cutting, embroidery, and wood carving. and other traditional artistic patterns, constantly enriching the patterns of medicine patch cloth.

At the same time, with the development of the oil-made umbrella industry, tung oil paper is used to engrave patterns, which saves labor and time. After oiling, the patterns are water-resistant, scratch-resistant, and have a long service life. , its patterns are richer and its craftsmanship is more mature.

The wide application of folk blue printed cloth has promoted the rapid development of the "printing dan" team. "Print dan" are also called "flower dan craftsmen". They only print and paste, but do not dye, and provide farmers with various forms of patterns. This kind of "printing burden" is also called "bald printing" in Jiangnan. They walk through streets and alleys and villages. One end of the burden is loaded with soybeans and lime powder, and the other end is equipped with scraping tools and patterns. Customers can choose Pattern processing, they constantly change patterns in order to achieve a prosperous business. According to the old master, at the end of the Qing Dynasty, there were still nearly a hundred people in the "stamp dan" team in Nantong. This convenient door-to-door printing service is very popular among farmers. Farmers send the scraped gray cloth to nearby dyeing houses, or they make indigo dyeing themselves. Due to the growing demand for blue calico, the popularity of indigo cultivation also promoted the development of the indigo industry. According to Chen Yutian, an old man from Chenggang Village, Renggang Township, Nantong City, his family has made a living growing indigo grass and vegetables for generations, and they start planting indigo (the variety is Polygonum indigo) every February of the lunar calendar.

The first bluegrass is harvested in May, and the second bluegrass is harvested in the hot summer season. During the harvest season, relatives and friends must be asked to help. On the day of cutting bluegrass, everyone gets up at 3 o'clock in the morning, and the harvested bluegrass must be completed before sunrise. , this kind of bluegrass has the highest indigo yield rate. After harvesting, tie the indigo into small bundles, put it head down into a large pit more than 1 meter deep, fill it with water, wait for the indigo to emerge, take out the stems and leaves, and add an appropriate amount of lime water to make the indigo sink. Remove the plug at the entrance of the other pit leading to the large pit of Blue Grass, so that the excess water on the indigo flows into the small pit. After turning the indigo into mud, put it in a pottery jar, keep it for your own use or sell it to others. Dyeing shop nearby. The method of making blue is roughly the same as recorded in history.

The local dyeing raw materials and the convenient process of self-spinning and self-weaving have enabled the dyeing and weaving industry in Jianghai area to develop rapidly and gradually become a well-known specialty area in the country. The craftsmanship of blue calico spread from the south of the Yangtze River to the north of the Yangtze River, and from Suzhou and Nantong to all regions of Jiangsu, forming a major production area centered in Jiangsu. In addition to being supplied locally, the products are also sold well all over the country. The printing technique spread and influenced the whole country. Shandong, Shanxi, Hunan, Hubei, Zhejiang, Anhui, and Northeastern provinces successively opened blue calico workshops; folk artists from various places combined with local customs and sentiments to create works that conformed to local aesthetic tastes. Blue calico patterns, resulting in various patterns of different styles. In the Northeast, blue calico is called "mahua cloth"; because soybeans are used in the raw material, Hubei is called "bean-dyed cloth"; in the blue calico process, patterns need to be carved, and Fujian is called "type dyeing"; while in Shandong In other areas, blue calico is still called "Suyin" (so named because Jiangsu is the birthplace of blue calico).