What kind of dye is used to color jeans? Is the dye harmful to the body?

Indigo dye is a natural dye, not synthetic. The harm to the body is almost none Authentic jeans are dyed with indigo, which has no coloration or striping on the surface of the fabric. After stone grinding, the color is more vivid and bright, slightly red, and there is no significant staining of the bag cloth. There is also the fact that it is more uniform in color. There is no obvious difference. Genuine jeans have a soft surface and no obvious hard lumps. Indigo, is a kind of reducing dye with a history of more than three thousand years. In the Warring States period, Xun Zi's famous saying "Green, out of blue is better than blue" originated from the dyeing technology at that time. The word "green" here refers to the color cyan, while "blue" refers to the blue grass used to make indigo. Before the Qin and Han dynasties, the use of indigo was already quite common.

China's people have gradually figured out the key technology of indigo making in their long-term practice, thus breaking the seasonal limitation of bluegrass dyeing. Ancient people's indigo-making method is as follows: firstly, mow the blue upside down in the pit, add water to filter, put the filtrate in the urn, add lime according to the proportion, and then use the wooden stick to hit the water dramatically to accelerate the dissolved indigo glycosides in the water and the air contact with the oxygen, so that it will oxidize to become indigo, after the precipitation, will be removed from the water, and so on, the water of the indigo is completely evaporated, then can be sheng into a container, and made of blue indigo. This technique of indigo making and dyeing is identical to the mechanism of modern synthetic indigo dyeing.

Like safflower, bluegrass can be made into a solid dye: first made into mud-like indigo, to be dyed, it is first fermented with lees, and the hydrogen and carbon dioxide produced during the fermentation process can reduce the indigo to indigo white. The white cloth dyed with indigo white, oxidized by air, can show blue color again. This fermentation and reduction technique of indigo was already in use during the Spring and Autumn and Warring States Periods, and the ancient method is still in use today. Around 100 B.C., indigo was made in India, and unlike the Chinese, they used the urine fermentation method to dye blue.