Dyeing is the application of dyes or pigments on textile materials such as fibers, yarns, and fabrics with the goal of achieving color with desired color fastness. Dyeing is normally done in a special solution containing dyes and particular chemical material. Dye molecules are fixed to the fiber by absorption, diffusion, or bonding with temperature and time being key controlling factors. The bond between dye molecule and fiber may be strong or weak, depending on the dye used. Dyeing and printing are different applications; in printing, color is applied to a localized area with desired patterns. In dyeing, it is applied to the entire textile.

Hank dyeing
Dyeing
Pigments for sale at a market in Goa, India
Cotton being dyed manually in contemporary India
Silk dye in pan on stove. Khotan

The primary source of dye, historically, has been nature, with the dyes being extracted from animals or plants. Since the mid-19th century, however, humans have produced artificial dyes to achieve a broader range of colors and to render the dyes more stable to washing and general use. Different classes of dyes are used for different types of fiber and at different stages of the textile production process, from loose fibers through yarn and cloth to complete garments.

Acrylic fibers are dyed with basic dyes, while nylon and protein fibers such as wool and silk are dyed with acid dyes, and polyester yarn is dyed with disperse dyes. Cotton is dyed with a range of dye types, including vat dyes, and modern synthetic reactive and direct dyes.

EtymologyEdit

The word 'dye' comes from the Middle English 'deie', and from the Old English 'dag' and 'dah'.[1] The first known use of the word 'dye' was before the 12th century.[2]

HistoryEdit

 
Dyeing in Fes, Morocco

The earliest dyed flax fibers have been found in a prehistoric cave in the Georgia and dates back to 34,000 BC.[3][4] More evidence of textile dyeing dates back to the Neolithic period at the large Neolithic settlement at Çatalhöyük in southern Anatolia, where traces of red dyes, possibly from ocher, an iron oxide pigment derived from clay, were found.[5] In China, dyeing with plants, barks, and insects has been traced back more than 5,000 years.[6]: 11  Early evidence of dyeing comes from Sindh province in Pakistan, where a piece of cotton dyed with a vegetable dye was recovered from the archaeological site at Mohenjo-daro (3rd millennium BCE).[7] The dye used in this case was madder, which, along with other dyes such as indigo, was introduced to other regions through trade.[7] Natural insect dyes such as Cochineal and kermes and plant-based dyes such as woad, indigo and madder were important elements of the economies of Asia and Europe until the discovery of man-made synthetic dyes in the mid-19th century. The first synthetic dye was William Perkin's mauveine in 1856, derived from coal tar. Alizarin, the red dye present in madder, was the first natural pigment to be duplicated synthetically in 1869,[8] a development which led to the collapse of the market for naturally grown madder.[6]: 65  The development of new, strongly colored synthetic dyes followed quickly, and by the 1870s commercial dyeing with natural dyestuffs was disappearing.

MethodsEdit

Dyeing can be applied at various stages within the textile manufacturing process; for example, fibers may be dyed before being spun into yarns, and yarns may be dyed before being woven into fabrics. Fabrics and sometimes finished garments themselves may also be dyed.[9] The stage at which a product is dyed varies depending on its intended end use, the cost to the manufacturer, its desired appearance, and the resources available, amongst other reasons. There are specific terms to describe these dyeing methods, such as:

  • Dope dyeing: In dope dyeing, pigments are added to the polymer solution itself before extruding the fibers. The process provides the dyed fibers with excellent fastness properties. The dope dyeing applies to synthetic fiber only. This method of dyeing is also known as solution dyeing[10] and 'mass coloration' or 'mass colored'. It has limited color options.[11][12]
  • Fiber dyeing: In fiber dyeing, the dyeing takes place at the fiber stage before they are spun into yarn. It is also called stock dyeing. Examples are melanges and medleys.[13][14]
  • Yarn dyeing: In yarn dyeing, the yarns are dyed first before the fabric manufacturing stage. The yarn dyeing happens in hanks or in package dyeing. Package dyeing is a method where yarns are wound on perforated cones placed in a dye vessel. The dye solution is then alternatively pushed inside out and vice versa. Examples are many stripes, patterned (checks) and jacquard designed fabrics.[9][15]
  • Piece dyeing: In piece dyeing, the dyeing takes place after producing fabrics with undyed yarns. Most of the solid dyed fabrics are dyed with the piece dyeing method, and the materials are also called piece dyed.[9]
  • Garment dyeing: In garment dyeing, the garments are constructed of undyed, but ready-for-dyeing, fabrics.[12]

ObjectiveEdit

The primary objective of dyeing is to apply uniform color to the substrate (fiber, yarn, or fabric) with required color fastness. Tie-dye and printing are the methods where the color is applied in a localized manner.[16]

ApplicationEdit

 
Exhaust dyeing vessel

Exhaust methodEdit

In the exhaust method, the dye is transported to the substrate by the dye liquor's motion. The dye is adsorbed onto the fibre surface and ideally diffuses into the whole of the fibre. Water consumption in exhaust application is higher than the continuous dyeing method.[16] There are three corresponding ways of dyeing with the exhaust method.

  1. Liqour circulating: loose stock, sliver, tow, yarn or fabric, is packed into canisters, wound onto cones or perforated beams and placed inside the dyeing vessel. In this way the liqour is pumped and revolves through the material which is stationary.
  2. Material circulating: Fabric winch dyeing and jiggers are the few forms in which material remains in motion and liqour stationary. In this the material moves through the stationary liqour.
  3. Liqour and material both in motion: Jet dyeing and softflow dyeing application methods where material and liqour both remain in motion.

Continuous methodEdit

In continuous method dye is transported to the substrate by passing it through the different stages but continuously.[16] The continuous method is an innovative method where many discrete dyeing stages are combined, such as applying color, fixation and, washing off of unfixed dyes.[17][18] Types of continuous dyeing are as follows

Waterless dyeing methodEdit

Waterless dyeing, also known as dry dyeing, is the newly developed and more sustainable dyeing method in which the dyes are applied to the substrate with the help of carbon dioxide or solutions that need less or no water compared to their counterparts.[19][20][21]

Selection of dyesEdit

The selection of the appropriate dyes is most important because any given dye does not apply to every type of fiber. Dyes are classified according to many parameters, such as chemical structure, affinity, application method, desired colour fastness i.e. resistance to washing, rubbing, and light.[16] The properties may vary with different dyes. The selection of dye depends on the objective in dyeing and affinity (to which material is to be dyed). Fastness of color largely depends upon the molecular size of the dyes and the sloubility. Larger molecular size serves better washing fastness results.[22]

Indigo dyes have a poor wash and rubbing fastness on denim (cotton), so they are used to produce washed-down effects on fabrics. In contrast, vat or reactive dyes are applied to cotton to achieve excellent washing fastness.

The next important criterion for selecting dyes is the assessment of hazards to human health and the environment. There are many dyes especially disperse dyes that may cause allergic reactions to some individuals,[23] and the negative impact on the environment.[24] There are national and international standards and regulations which need to comply.

Direct applicationEdit

 
Chemical structure of Vat Green 1, a type of vat dye

The term "direct dye application" stems from some dyestuff having to be either fermented as in the case of some natural dye or chemically reduced as in the case of synthetic vat and sulfur dyes before being applied. This renders the dye soluble so that it can be absorbed by the fiber since the insoluble dye has very little substantivity to the fiber. Direct dyes, a class of dyes largely for dyeing cotton, are water-soluble and can be applied directly to the fiber from an aqueous solution. Most other classes of synthetic dye, other than vat and surface dyes, are also applied in this way.

The term may also be applied to dyeing without the use of mordants to fix the dye once it is applied. Mordants were often required to alter the hue and intensity of natural dyes and improve color fastness. Chromium salts were until recently extensively used in dyeing wool with synthetic mordant dyes. These were used for economical high color fastness dark shades such as black and navy. Environmental concerns have now restricted their use, and they have been replaced with reactive and metal complex dyes that do not require mordant.

Yarn dyeingEdit

 
Dyed wool reels (CSIRO)

There are many forms of yarn dyeing. Common forms are the package form and the hanks form. Cotton yarns are mostly dyed at package form, and acrylic or wool yarn are dyed at hank form. In the continuous filament industry, polyester or polyamide yarns are always dyed at package form, while viscose rayon yarns are partly dyed at hank form because of technology.[25]

The common dyeing process of cotton yarn with reactive dyes at package form is as follows:

  1. The raw yarn is wound on a spring tube to achieve a package suitable for dye penetration.
  2. These softened packages are loaded on a dyeing carrier's spindle one on another.
  3. The packages are pressed up to a desired height to achieve suitable density of packing.
  4. The carrier is loaded on the dyeing machine and the yarn is dyed.
  5. After dyeing, the packages are unloaded from the carrier into a trolley.
  6. Now the trolley is taken to hydro extractor where water is removed.
  7. The packages are hydro extracted to remove the maximum amount of water leaving the desired color into raw yarn.
  8. The packages are then dried to achieve the final dyed package.

After this process, the dyed yarn packages are packed and delivered.

Space dyeingEdit

 
Space dyed yarn

Space dyeing is a technique of localized color application that produces a unique multicolored effect.[26][27]

History of garment dyeingEdit

Garment dyeing is the process of dyeing fully fashioned garments subsequent to manufacturing, as opposed to the conventional method of manufacturing garments from pre-dyed fabrics.

Up until the mid-1970s the method was rarely used for commercial clothing production. It was used domestically, to overdye old, worn and faded clothes, and also by resellers of used or surplus military clothing. The first notable industrial use of the technique was made by Benetton, which garment dyed its Shetland wool knitwear.

Complex garment dyeingEdit

In the mid-1970s the Bologna clothing designer Massimo Osti began experimenting with the garment dyeing technique. His experimentation over the next decade, led to the pioneering of not just the industrial use of traditional garment dyeing (dyeing simple cotton or wool garments) but, more importantly, the technique of “complex garment dyeing” which involved dyeing fully fashioned garments which had been constructed from multiple fabric or fiber types (e.g. a jacket made from both nylon and cotton, or linen, nylon and polyurethane coated cotton) in the same bath.

Up until its development by Massimo Osti (for his clothing brand C.P. Company), this technique had never been successfully industrially applied in any context. The complexity lay in developing both a practical and chemical understanding of how each fabric responded differently to the dye, how much it would shrink, how much color it would absorb, developing entirely new forms of quality control to verify possible defects in fabric before dyeing etc.

Beyond the industrial advantages of the technique (purchasing fabric in one color, white or natural, you may produce as many colors as you wish etc.), the artistic advantages of the technique were considerable and in many ways paved the way for the creation of the clothing style today known as Italian Sportswear. These advantages included

  • the way in which different fibers absorbed the dye's color allowed for the creation of incredibly nuanced differences in color tones and a harmony that is impossible to achieve any other way
  • the garment dyeing process naturally gave the fabric a “worn-in” hand allowing for the development of the casual and relaxed version of the classic menswear look which characterizes Italian sportswear
  • the fact that each fabric and fiber type responds differently to the dye also produces a “deconstructed” effect, whereby the consumer's attention is drawn to the construction techniques of the jacket. For example: a more densely woven fabric absorbs the color less intensely than a more open weave, the polyester stitching used for a cotton garment does not absorb any dye color, producing a contrast color stitch etc.

The disadvantages included:

  • a relatively high failure rate for garments (between 5–10%)
  • the difficulty in achieving a very tailored look due to difficulties in precisely calculating shrinkage rates
  • high research and prototyping costs in order to understand how fabrics will behave in production

Today, whilst garment dyeing is a diffusely employed as an industrial technique around the globe, predominantly in the production of vintage style cotton garments and by fast fashion suppliers, complex garment dyeing is still practiced almost exclusively in Italy, by a handful of premium brands and suppliers who remain committed to the art.

Removal of dyesEdit

 
The dyer of the fountain "Weberbrunnen" in Monschau (Germany).

If things go wrong in the dyeing process, the dyer may be forced to remove the dye already applied by a process called "stripping" or discharging. This normally means destroying the dye with powerful reducing agents such as sodium hydrosulfite or oxidizing agents such as hydrogen peroxide or sodium hypochlorite. The process often risks damaging the substrate (fiber). Where possible, it is often less risky to dye the material a darker shade, with black often being the easiest or last option.

See alsoEdit

ReferencesEdit

  1. ^ "Dyeing". The Free Dictionary By Farlex. Retrieved 2012-05-25.
  2. ^ "Dye". Merriam-Webster. Retrieved 2012-05-25.
  3. ^ Balter, M. (2009). "Clothes Make the (Hu) Man". Science. 325 (5946): 1329. doi:10.1126/science.325_1329a. PMID 19745126.
  4. ^ Kvavadze, E; Bar-Yosef, O; Belfer-Cohen, A; Boaretto, E; Jakeli, N; Matskevich, Z; Meshveliani, T (2009). "30,000-year-old wild flax fibers" (PDF). Science. 325 (5946): 1359. Bibcode:2009Sci...325.1359K. doi:10.1126/science.1175404. PMID 19745144. S2CID 206520793. Supporting Material
  5. ^ Barber (1991), pp. 223-225.[full citation needed]
  6. ^ a b Goodwin, Jill (1982). A Dyer's Manual. Pelham. ISBN 978-0-7207-1327-5.
  7. ^ a b Bhardwaj, H.C. & Jain, K.K., "Indian Dyes and Industry During 18th-19th Century", Indian Journal of History of Science 17 (11): 70-81, New Delhi: Indian National Science Academy.
  8. ^ Hans-Samuel Bien, Josef Stawitz, Klaus Wunderlich "Anthraquinone Dyes and Intermediates" in Ullmann’s Encyclopedia of Industrial Chemistry, 2005, Weinheim: 2005. doi:10.1002/14356007.a02 355.
  9. ^ a b c EPA Office of Compliance Sector Notebook Project: Profile of the textile industry. Office of Compliance, Office of Enforcement and Compliance Assurance, U.S. Environmental Protection Agency. 1997. p. 32. ISBN 978-0-16-049401-7.
  10. ^ Wingate, Isabel Barnum (1979). Fairchild's dictionary of textiles. Internet Archive. New York : Fairchild Publications. p. 571. ISBN 978-0-87005-198-2.
  11. ^ MATHEWS, KOLANJIKOMBIL (2017). Encyclopaedic Dictionary of Textile Terms: Four Volume Set. Woodhead Publishing India PVT. Limited. p. 464. ISBN 978-93-85059-66-7.
  12. ^ a b Mahapatra, N. N. (2019-01-31). Textile Dyeing. Woodhead Publishing India PVT. Limited. p. 159. ISBN 978-93-85059-91-9.
  13. ^ Weinhold, Virginia Beamer (1988). Interior Finish Materials for Health Care Facilities: A Reference Source for All Installations where Durable Surfaces are Needed. Thomas. p. 36. ISBN 978-0-398-05397-0.
  14. ^ Needles, Howard L. (1981). Handbook of Textile Fibers, Dyes, and Finishes. Garland STPM Press. ISBN 978-0-8240-7046-5.
  15. ^ Wingate, Isabel Barnum (1979). Fairchild's dictionary of textiles. Internet Archive. New York : Fairchild Publications. pp. 431, 432. ISBN 978-0-87005-198-2.
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  17. ^ The U.S. Textile and Apparel Industry: A Revolution in Progress : Special Report. Congress of the U.S., Office of Technology Assessment. 1987. p. 54.
  18. ^ a b c d Purushothama, B. (2019-01-31). Handbook of Value Addition Processes for Fabrics. Woodhead Publishing India PVT. Limited. pp. 83, 95. ISBN 978-93-85059-92-6.
  19. ^ Nayak, Rajkishore (October 2019). Sustainable Technologies for Fashion and Textiles. Elsevier. p. 243. ISBN 978-0-08-102867-4.
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  22. ^ Chakraborty, J. N.; Chakraborty, J. N. (2015-05-05). Fundamentals and Practices in Colouration of Textiles. CRC Press. p. 23. ISBN 978-93-80308-47-0.
  23. ^ https://www.hse.gov.uk/textiles/dyes-dyeing.htm
  24. ^ You, Sauwai; Cheng, Stephen; Yan, Hong (2009). "The impact of textile industry on China's environment". International Journal of Fashion Design, Technology and Education. 2: 33–43. doi:10.1080/17543260903055141. S2CID 111141147.
  25. ^ Farer Thread
  26. ^ Choudhury, A. K. Roy (2006-01-09). Textile Preparation and Dyeing. Science Publishers. ISBN 978-1-57808-404-3.
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