What color is indigo?

Indigo, a dark blue organic dye, is called "indigo". Also known as "indigo" and "indigo", it is a mixed color of blue and purple. Indigo pigment is one of the oldest pigments known to mankind, which is widely used in food, medicine and printing and dyeing industries. The application of indigo as a fabric dye can be traced back to at least 2500 BC.

Some clothes worn by ancient Egyptian mummies and blue linen fabrics unearthed in Mawangdui, China, are all dyed with indigo. Blue Indian Yao, a branch of Yao nationality in China, is named after its unique technology of making and using indigo dyed cloth. In the food industry, indigo is used as food pigment in the form of its sodium sulfonate or its aluminized form, which is called "Bright Blue" and brilliant blue aluminum lake in China and "Indigo" in the form of its sodium sulfonate in the United States.

Method for produce indigo

In the long-term practice, our people have gradually explored the key technology of making indigo, thus breaking the seasonal restriction of blue grass dyeing. In ancient times, the method of making indigo was to put the cut indigo upside down in a pit, filter it with water, put the filtrate into an urn, add lime in proportion, and then bang on the water surface with a wooden stick to speed up the contact between indigo glycoside dissolved in water and air oxygen.

It is oxidized into indigo, and after precipitation, the water is removed. After the water of indigo is completely evaporated, it can be put into a container to make indigo. This indigo manufacturing and dyeing technology is completely consistent with the dyeing mechanism of modern synthetic indigo. Indigo was made in India around 100 BC. Unlike China people, they are dyed by urine fermentation.