Mass settles to the bottom of the vat and is then extracted. Indigo mass is then boiled, filtered and pressed to be dry as much as possible. Final product is a dry mass cut into cubes. The first synthetic indigo dye was made by German chemist Adolf von Baeyer in but synthesis of indigo those first tries was impractical. Experimenting continued and first commercially practical synthetic indigo was made in Home Jeans History History of Indigo.
History of Indigo - Blue of Blue Jeans Indigo is a type of blue dye that is generally used for coloring of cotton yarn that is used for production of denim cloth for blue jeans. Reference Collections. Asian Textiles. Dye Analysis. Fiber Reference Image Library. Forbes Pigments. Uemura Dye Archive. Additional Resources. Within 14 years their work resulted in the first commercial production of the synthetic dye.
In Baeyer was awarded the Nobel Prize for his discovery. In recent years, the synthetic process used to produce indigo has come under scrutiny because of the harsh chemicals involved.
New, more environmentally responsible methods are being sought by manufacturers. The raw materials used in the natural production of indigo are leaves from a variety of plant species including indigo, woad, and polygonum. Only the leaves are used since they contain the greatest concentration of dye molecules.
In the synthetic process, a number of chemicals are employed as described below. Here, the indoxyl-rich mixture is stirred with paddles to mix it with air. This allows the air to oxidize the indoxyl to indigotin, which settles to the bottom of the tank. The upper layer of liquid is siphoned away and the settled pigment is transferred to a third tank where it is heated to stop the fermentation process.
The resultant mixture is filtered to remove impurities and dried to form a thick paste. Historically, the Japanese have used another method which involves extracting indigo from the polygonum plant.
In this process the plant is mixed with wheat husk powder, limestone powder, lye ash, and sake. The mixture is allowed to ferment for about one week to form the dye pigment which is called sukumo. The chemical symbol for indican, the compound found in the leaves of the indigo plant that is used to make indigo dye. During indigo manufacture, the reaction process is continuously monitored to ensure the chemicals are combined in the proper ratios.
If any of these variables deviate from specifications, the resulting reaction product can be affected. Typically, poor quality control results in lower yield of the dye, which increases costs for the manufacturer. To ensure that manufacturers can consistently purchase the same shade of dye, indigo is assigned a Color Index number that defines its shade. Indigo production produces a variety of waste products which must be handled carefully. In addition to the reactants described above, there are other reaction side products that are produced along with the indigo.
Overview History of use Making the pigment Technical details. Today, indigo is also produced by the bacterium E. To make painting pigments, the dye is "fixed" to a ground white material, in a processed called "laking. The ground pigment: Pile of ground Indigo.
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