Indigo is so safe for living things that is has long been used to color medical sutures of polyester, which is required because undyed-white sutures appear much like nerves and when the surgeon removes the sutures, the color prevents a nerve from being mistakenly cut. Indigo has also been long in use to produce the blue color in fireworks !.ĭenim Sewing Threads – Garment Stitching Recommendations And Guide Is Indigo Safe For Living Things? The highly-pure Food Blue 1 is used for coloring beverages, toothpaste, candy, mouthwash – in short, anything edible that is blue will use this form of Indigo, as well as use as a hair dye. Acid Blue 74 and when insolubilized with aluminum salts becomes C.I. Food Blue 1 is produced by sulfonating Vat Blue 1 in order to produce 5,5′ indigotin disulphonic acid. Vat Brown 42 are simply mixtures of blue Indigo and thioindigo. One way to test the dye in order to assure that it is thioindigo, is to disperse it in chloroform in which the color shifts from a violet to a yellowish-red. Thioindigo possesses the unusual characteristic of photochromism, changing color on exposure to light. This is a very versatile vat red in that it can be blended with blue Indigo in alkaline sodium hydrosulfite as in normal Indigo dyeing, be applied like a sulfur dye with sodium polysulfide in continuous or batch opertions as well as garment dyeing. Vat Red 41, a bright red thioindigo which can be produced with thiosalicylic acid. denim company, Avondale, used this dye on a small 12-rope range to produce a fabric that was wildly popular in the fashion denim business. Vat Blue 5 produced by brominating Vat Blue 1 in nitrobenzene. Pigment Blue 66, when it is applied in printing. In the 19 th century natural Indigo was commonly used for printing and many of these new colorants were used for printing, especially of calico fabrics. The COLOUR INDEX, published by the Society of Dyers and Colourists in the 1924 edition, lists 54 colorants that were variants of Indigo !. Once the technology for production of synthetic vat dyes was developed, a wide range of new colorants based on Indigo were available by the 1920’s. In 1897, the BASF company began marketing synthetic Indigo which greatly increased the supply of Indigo-dyed fabrics. This dye is chemically different from the plant-derived Indigo only by the presence of bromine in the structure. There was another natural Indigo that was produced by shellfish at the eastern end of the Mediterranean Sea, known as Tyrian Purple, famous for producing the “royal purple” shade in antiquity. ![]() Indigo was employed as a blue dye for wool primarily, until the 20 th century, in fact, Indigo is a better dye for wool than cotton, being much easier to apply. Indigo has throughout history been the colorant most in demand and current production levels are reported to be around 17,000 tons per year. Indigo cultivation was introduced in the Americas in the 18 th century, first in the West Indies and then in South Carolina. Luckily, with a lot of the factories we are working with, this water is recycled and therefore reused multiple times.Indigo has been in use as a blue colorant for thousands of years as a natural dye, which was produced from the Indigopheraplant in India and China and with woad in Europe. ![]() The average post-washing process uses about 11 L per kg of yarn to rinse. In this step, all the excess indigo pigment and chemicals are washed off the fabric with large amounts of water. The last step in the dyeing process is the post-washing stage. The more dyebaths are used, the deeper the indigo colour will be. In between baths they’re exposed to air, so that the oxygen can make a reaction with the dye and turn it blue. With every dye bath the yarns change in color from yellow, to green, to eventually blue. The yarns are ready for some colour! The yarns go through several – 2 to 9 – dyeing baths, containing a combination of water, indigo pigment and chemicals. The chemicals open up the yarns, so the dye can settle in. A bunch of water is combined with several chemicals to rinse the yarns one last time. In the pre-washing stage, the yarns are prepared for dyeing. It has 3 major steps: pre-washing, dyeing and post-washing. The indigo dyeing process is rather complex, but we’ll take you by the hand.
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