文章目录
Product Overview
Indigo is one of the oldest known pigments, widely used in the food, pharmaceutical, and textile dyeing industries. Its use as a fabric dye dates back to at least 2500 BC. Indigo-dyed fabrics have been found in ancient Egyptian mummies and in blue hemp textiles from China’s Mawangdui tomb. The Yao people of China are named “Lan Dian Yao” for their unique indigo dyeing techniques. In the food industry, indigo is used as a food colorant in the form of its sodium sulfonate or its aluminum lake, known as “Brilliant Blue” in China and “Indigotine” in the United States.
Indigo Production Process
Chemical synthesis.
(1) Indigo preparation: Edible indigo is actually disodium indigo disulfonate, produced by sulfonating indigo with concentrated sulfuric acid. After sulfonation, the mixture is diluted with water, neutralized with soda ash, salted out with sodium chloride, filtered, washed, and dried to obtain the final product. Each ton of product consumes 210 kg of indigo powder (100%).
(2) Preparation of indigo aluminum lake: Aluminum hydroxide is prepared from aluminum chloride or aluminum sulfate and sodium carbonate, then added to a solution of indigo carmine to precipitate the product.
Benefits and Uses of Indigo
Indigo is primarily used as a colorant.
Applications of Indigo
Indigo is mainly used for dyeing cotton yarn, cotton fabric, wool, or silk. It is an important vat dye, known for its excellent lightfastness, weather resistance, and thermal stability, providing a blue hue. It can be used to prepare liquid dispersions and is mainly applied in the coloration of viscose fiber pulp and dyeing. It is also used in biochemical reagents and indicators, as well as for dyeing cotton yarn, cotton fabric, wool, or silk. As a food colorant, it is approved for use in colored strands of red and green, with a maximum dosage of 0.02g/kg; in juice drinks, carbonated beverages, compound wines, candies, cakes, decorated and dyed cherries (for decoration), and green plums, the maximum dosage is 0.10g/kg; in pickled vegetables, the maximum dosage is 0.01g/kg.
Packaging and Storage of Indigo
Storage Conditions: This product should be sealed, protected from light, stored in a dry, cool, and well-ventilated place.
Packaging: Bulk 25kg/paper drum, samples 1kg/aluminum foil bag, or customized packaging upon request.
Transportation: By express or logistics, domestic express delivery within three days, logistics within five days. Quotes generally include domestic shipping costs.
Shelf Life: Two years
Plant Sources
Organic deep blue dye is made by fermenting leaves of indigo plants, such as Polygonum tinctorium, Isatis tinctoria, Indigofera tinctoria, and others containing indican. It is also synthesized artificially (as described in ancient texts: "All types of indigo plants can produce indigo dye" – Song Yingxing, *Tiangong Kaiwu*). The dyed fabric color is long-lasting. Commonly known as "Indigo," in some regions, it is referred to as "Indigo Blue."
Indigo is a vat dye with over three thousand years of history. The famous quote from Xunzi during the Warring States period, "Green is extracted from blue but surpasses blue," refers to the dyeing technique of the time. Here, "green" refers to cyan, and "blue" refers to the indigo-producing plant. Indigo was already widely used before the Qin and Han Dynasties.
