The production process of indigo.

Indigo is the most commonly used dye of Li nationality, and indigo dyeing is a method of dyeing the dyed object with plant dyes obtained from indigo plants. Indigo, commonly known as indigo and bluegrass in Hainan, is the earliest plant dye used in China. The color of fabric dyed with indigo is mainly blue. With the increase of dyeing times, the color gradually deepens to dark blue, and the color is full, firm, washable and not easy to decolorize. It is common for Li people to dye indigo and plant bluegrass. Blue grass is the general name of many kinds of plants that can make indigo, and there are about four or five kinds of blue grass commonly used by Li people. In the investigation, we saw one of them-fake indigo. Fake indigo is ugly and generally does not need special management. In the village where Hongnei Village in Ledong Vocational School and Qijia Village in the Yangtze River overlap, we saw many pieces of fake indigo planted around the house, and the clusters were quite lush. To dye with blue grass, you must first make indigo. Indigo production is to extract indigo from bluegrass. First, pick the tender stems and leaves of bluegrass, put them in a jar, soak them in water, and expose them to the sun. After a few days, bluegrass will rot and ferment. When the soaking solution of bluegrass changes from yellow-green to blue-black, impurities should be removed and a certain amount of lime water should be added. After precipitation, deep blue muddy sediment is left on the bottom layer, and indigo production is completed. Dyeing is called dyeing when the dyed object is immersed in dye solution. Indigo dyeing is a redox reaction at normal temperature and pressure. Generally, it takes several or even a dozen times of repeated impregnation and drying to achieve the ideal effect. Grandma Xing Baizuo from Coincidence Village showed us the process of extracting indigo and dyeing. Grandma first rolled the leaves and stems of picked bluegrass into bundles, put them in a clay pot and soaked them for three days, then took them out to squeeze water, put them in snail ash for about an hour, and then poured out the water, and a precipitate, namely indigo, was formed in the clay pot. Next, add plant ash water and rice wine, let it stand for 2-6 days according to its fermentation degree, soak it in white cotton yarn for 2 hours, then take it out, twist, pat, knead and pull it for half an hour, then put it in a clay pot to fully soak it, take it out after about 2 hours, squeeze out water, air-dry and oxidize it, and repeat dip dyeing and air-dry after half an hour until it reaches the required dark blue. Finally, the dyed yarn is rinsed in the river, and the unsatisfactory yarn is dyed again until it is satisfactory. Shell ash and plant ash contain many metal elements, which act as mordants. Adding wine to the dye can also improve the color to some extent, and wine can also enhance the permeability of the dye, so that cotton yarn has better dyeing effect and fastness.