Another preindustrial method, used in Japan, was to dissolve the indigo in a heated vat in which a culture of thermophilic , anaerobic bacteria was maintained. Some species of such bacteria generate hydrogen as a metabolic product, which can convert insoluble indigo into soluble indigo white.
Cloth dyed in such a vat was decorated with the techniques of shibori tie-dye , kasuri, katazome, and tsutsugaki. Examples of clothing and banners dyed with these techniques can be seen in the works of Hokusai and other artists.
Two different methods for the direct application of indigo were developed in England in the eighteenth century and remained in use well into the nineteenth century.
The first method, known as pencil blue because it was most often applied by pencil or brush, could be used to achieve dark hues. Arsenic trisulfide and a thickener were added to the indigo vat. The arsenic compound delayed the oxidation of the indigo long enough to paint the dye onto fabrics.
The second method was known as china blue due to its resemblance to Chinese blue-and-white porcelain. Instead of using an indigo solution directly, the process involved printing the insoluble form of indigo onto the fabric. The indigo was then reduced in a sequence of baths of iron II sulfate, with air-oxidation between each immersion. The china blue process could make sharp designs, but it could not produce the dark hues possible with the pencil blue method.
Around the glucose process was developed. It finally enabled the direct printing of indigo onto fabric and could produce inexpensive dark indigo prints unattainable with the china blue method. It is insoluble in water, alcohol , or ether but soluble in chloroform , nitrobenzene , or concentrated sulfuric acid. The chemical structure of indigo corresponds to the formula C 16 H 10 N 2 O 2. The naturally occurring substance is indican, which is colorless and soluble in water.
Mild oxidation , such as by exposure to air, converts indoxyl to indigo. The manufacturing process developed in the late s is still in use throughout the world. In this process, indoxyl is synthesized by the fusion of sodium phenylglycinate in a mixture of sodium hydroxide and sodamide. Several simpler compounds can be produced by decomposing indigo; these compounds include aniline and picric acid. The only chemical reaction of practical importance is its reduction by urea to indigo white.
The indigo white is reoxidized to indigo after it has been applied to the fabric. Indigo treated with sulfuric acid produces a blue-green color. It became available in the mids. Sulfonated indigo is also referred to as Saxon blue or indigo carmine. Tyrian purple was a valuable purple dye in antiquity. It was made from excretions of a common Mediterranean Sea snail. It has never been produced synthetically on a commercial basis.
Indigo may be synthetically manufactured in a number of different ways. This produces indoxylcarboxylic acid, a material that readily decarboxylates and oxidises in air to form indigo.
The modern synthesis of indigo is slightly different from that route originally used and its discovery is credited to Pfleger in In this process, N-phenylglycine is treated with an alkaline melt of sodium and potassium hydroxides containing sodamide.
This produces indoxyl , which is subsequently oxidised in air to form indigo. Categories: Natural dyes Nitrogen heterocycles. Read what you need to know about our industry portal chemeurope. My watch list my. My watch list My saved searches My saved topics My newsletter Register free of charge.
Keep logged in. Eventually, the demand for indigo outstripped supply and a synthetic alternative was developed such is the way, unfortunately with many things in the industrialized and modern world and the cheaper alternative caused a massive decline in natural indigo production.
Indigo is derived from plants. There are many native plants that can produce indigo — some things you would never suspect like rhubarb and cabbage can provide the blue hue! The most popular plant used in production comes from the leaves of Indigofera tinctoria, which thrives in hot humid places and is commercially grown in India and El Salvador.
As with coffee beans and cacao, the blue dye is unique to the region it has come from and the temperature and soil it is grown in, giving variations in pigment for the more discerning of artisans and those who appreciate finer details. This is in stark contrast to synthetic indigo, which is derived from petrochemicals oil and its production produces toxic waste.
Natural indigo is mostly cultivated in rural communities in developing nations and its origins are usually very easy to trace, in this way it provides employment to farmers and communities in need of an economic boost. It has a high level of impurities, which provide a wide range of color variations for the artist to play with.
Indigo can dye lots of materials and is especially good for cotton indigo was the first dye used to color the original blue jeans but also perfect for linens, silk, wool, leather and feathers and even materials like cane, wicker, shells and buttons.
I had to include a little bit here on what some modern pieces of fashion look like using the delicate process of indigo dying using the indigo dye plant and one of my favorites are the pieces created by Lookout and Wonderland. Efficient reaction process is achieved through it. After completion of the chemical reaction processes, the finished dye has to be washed to remove impurities and then dried. Indigo blue is the primary color of blue jeans in the west, its importance as result is increased in present time.
In the United States indigo is primarily used to dye cotton clothes and blue jeans. Over one billion pairs of jeans around the world are dyed blue with indigo. Deep navy blue colors on wool are produced by indigo dye. The Romans in earlier times, used indigo as a pigment for painting and for medicinal and cosmetic purposes. It was a luxury item for Arabs which was imported to the Mediterranean from India by Arab merchants.
Indigotinesulfonate is used as a dye in renal function testing and as a reagent for the detection of nitrates and chlorates. It is also used in the testing of milk. It was the original dye of the "Levi's" blue jeans, a trademark color for durability.
It is the only natural blue dye that is permanent in nature. On many instances from Europe to the Arab world, historical use of blue to stain skin for war, religious and social rites were found. Indigo in combination with resist techniques create decorative wooden items. In certain cultures indigo dye is also used for craft purpose such as on paper, leather and on silk. The Future Scientists all over the world are carrying out research programmes on inventing a method of producing indigo dye which is less hazardous to health.
Using biocatalysts in the dye reaction process might work out for producing environment friendly dye. By making through a biological route, indigo dye would become one of the first high-volume chemicals by the biological route.
Genencor International, of Rochester New York, is experimenting on a process to produce indigo using biotechnology. However, at this stage the technology is expensive and production costs might be prohibitive. The natural dye comes from several species of plant, but nearly all indigo produced today is synthetic in nature.
Reference: www. The information provided on this website is for educational or information purposes only.
Anyone using the information on Fibre2fashion. The views and opinions of the authors who have submitted articles to Fibre2fashion. If you wish to reuse this content on web, print or any other form, please seek for an official permission by writing to us on editorial fibre2fashion. We use cookies for better user experience. By continuing to browse this site you agree to its Cookie Policy or can decide to change your browser settings anytime.
Got it. Toggle navigation Fibre2Fashion. Make to Order. ShanghaiTex Tue, November 23rd, Featured Fairs. Get your copy. By: Fibre2Fashion. Disclaimer Responsibility: Fibre2fashion. No Endorsement: Fibre2fashion. Submit your Request If you wish to reuse this content on web, print or any other form, please seek for an official permission by writing to us on editorial fibre2fashion.
Fibre2Fashion Monthly Newsletter. F2F Weekly Insights. Technical Textiles eNews Weekly. Please refer our Privacy Policy before submitting your information.
0コメント