Textile bleaching

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Early method of bleaching cotton and linen goods on lawns Old method of Bleaching Figure 20 Appleton 1884.tif
Early method of bleaching cotton and linen goods on lawns
A bleach worker Catalyst 2188.jpg
A bleach worker

The textile bleaching (or bleaching of textiles) is one of the steps in the textile manufacturing process. The objective of bleaching is to remove the natural color for the following steps such as dyeing or printing or to achieve full white. [1] All raw textile materials, when they are in natural form, are known as 'greige' material. They have their natural color, odor and impurities that are not suited to clothing materials. Not only the natural impurities will remain in the greige material, but also the add-ons that were made during its cultivation, growth and manufacture in the form of pesticides, fungicides, worm killers, sizes, lubricants, etc. The removal of these natural coloring matters and add-ons during the previous state of manufacturing is called scouring and bleaching. [2] : 193  [3] [4] [5]

Contents

A continuous bleaching range is a set of machines to carry out bleaching action. It consists of several compartments in which fabric moves from one side to another with the help of guide rollers and is treated with chemicals, heated, rinsed, and squeezed. Continuous bleaching is possible for the fabrics in open-width or rope form. [6] [7]

History

Bleaching can be dated back to at least 1000BC from an Egyptian list found in the tomb of Rekh-mi-re at Thebes, which mentioned both bleached and unbleached linen. [8] Mulrooney dates it back as far as 5000BC, [9] while Walton claims it was introduced to Egypt from Asia. [10] It’s plausible that it was discovered independently by different cultures. It’s generally assumed to have developed after noticing that garments are naturally bleached by sunlight and washing. [8] [9] Wood ash (potash, or impure potassium hydroxide) was an early form of soap, known to have been used in bleaching since at least 1AD. [10] [11] This process of washing cloth in a solution of ashes (lye) and left in the sun, known as Grassing, is one of the oldest methods of bleaching textile goods. To bleach linen and cotton-based fabrics, the Grassing method has been used. Linen has long been bleached in Europe with Grassing method. [12] The linens were laid out on the grass for over seven days after boiling with the ''lyes of ashes and rinsing''. [13] Bleachfield was an open area to spread cloth, it was a field near watercourse used by a bleachery. Bleachfields were common in and around the mill towns during the British Industrial Revolution [14]

The Dutch were bleaching by about the 12th century and are credited with soaking the bleached cloth in a bath of soured milk for 5 – 8 days. [9] [11] [15] This softened and neutralised the harsh effects of the caustic lye. [9] By the 17th century the Dutch were renowned for their bleaching skills and much of their trade was for customers abroad. [16] [15] Around 1756 an alternative to soured milk was proposed by the Scottish doctor, Francis Home using a weak solution of sulphuric acid. [17] This was made commercially viable by John Roebuck's manufacture of sulphuric acid and reduced the soaking time to 12 – 24 hours. [15] A final rinse and drying finished the bleaching process.

The English East India Company imported bleached, painted and printed calico from India during the 17th century. [18] This disrupted the English silk and wool trades [19] and an act of parliament, the Encouragement of Manufactures Act 1698 (11 Will. 3. c. 10), was passed that prohibited the wearing of printed calicos manufactured in China, India or Persia. [20] This inadvertently established a calico bleaching and printing industry using unbleached Indian calico. A second law in 1721 prohibited the use and wear of all printed, painted, stained or dyed calicoes [21] which stimulated demand for linen and fustian. The calico acts were repealed in 1774 when cloth was made using imported cotton from America. [22]

Discovery of Chlorine

After discovering Chlorine in the late 18th century, when chemical bleaching came into existence, the chemical bleaching rose above Grassing, as it was quicker and possible in indoors. [12] [14] [13]

The French chemist Claude Louis Berthollet first demonstrated the bleaching properties of chlorine and subsequently developed liquid bleaches around 1789. James Watt is credited with bringing it to Britain, and a fellow Scot, Charles Tennant patented a more practical bleaching powder that made chlorine-based bleaching a commercial success.

Scouring

Scouring is the first process carried out with or without chemicals, at room temperature or at suitable higher temperatures with the addition of suitable wetting agents, alkali and so on. Scouring removes the impurities such as waxes, pectins and makes the textile material hydrophilic or water absorbent. [23] [24] [25] : 78  Scouring is then followed by the bleaching process. [2] : 169  [2] : 193 

Bleaching

The term "bleach" originates from a French word signifying "to whiten." In essence, the process of bleaching involves whitening by removing substances that impart color to the material undergoing the bleaching treatment. [26] Bleaching is the process of decolorizing the material after it has been scoured. [2] : 169  Bleaching textiles can be classified as oxidative bleaching and reductive bleaching which can be carried out with oxidizing and reductive bleaching agents. [27] : 161  Bleaching agents attack the chromophores and alter the color absorbing properties of the objects. [28]

Oxidative bleaching

Generally oxidative bleachings are carried out using sodium hypochlorite, sodium chlorite or sulfuric acid.

Vegetable fibres, animal fibers, and mineral fibres are the three major types of natural fibers. Natural fibers such as cotton, ramie, jute, wool, and regenerated fibers such as bamboo are all generally bleached with oxidative methods. [29]

Oxygen bleaching action

It is the conjugated double bonds of the substrate that makes the substrate capable of absorbing visible light. Hence, it looks yellower and need bleaching. When bleaching action carries out with oxygen, it removes the chromophoric sites and makes the cloths whiter. Oxygen is a degrading bleaching agent. Its bleaching action is based on ''destroying the phenolic groups and the carbon–carbon double bonds.''. [30] The major source of chemical bleaching is Hydrogen peroxide H
2O
2 that contains a single bond, (–O–O–). When this breaks down it gives rise to very reactive oxygen specie, which is the active agent of the bleach. Around sixty percent of the world Hydrogen peroxide is used in chemical bleaching of textiles and wood pulp. [31]

Reductive bleaching

Reductive bleaching is done with sodium hydrosulphite, a powerful reducing agent. Fibres like polyamides, polyacrylics and polyacetates can be bleached using reductive bleaching technology. [29]

Textile whitening

Bleaching of textiles may include an additional application of optical brighteners (OBAs). Optical brightening agents are chemical compounds that absorb light in the ultraviolet and violet region (usually 340-370 nm) of the electromagnetic spectrum, and re-emit light in the blue region (typically 420-470 nm) by fluorescence. After scouring and bleaching, optical brightening agents are applied to make the textile material appear a more brilliant white. These OBAs are available in different tints such as blue, violet and red. [32]

Whiteness

Pope Francis at the Vatican. Popes have traditionally worn white since 1566. Canonization 2014-The Canonization of Saint John XXIII and Saint John Paul II (14036966125).jpg
Pope Francis at the Vatican. Popes have traditionally worn white since 1566.

Whiteness in colorimetry is the degree to which a surface is white. [33] The term "whiteness" refers to the degree to which a surface resembles the properties of a perfect reflecting diffuser, i.e. an ideal reflecting surface that neither absorbs nor transmits light, but instead reflects it evenly in all directions. [34]

CIE Whiteness

CIE Whiteness is a formula that measures the degree of whiteness. [34] The CIE Whiteness Index is a measure or methodology developed by the Commission on illumination. [35]

See also

Related Research Articles

<span class="mw-page-title-main">Calico</span> Type of textile

Calico is a heavy plain-woven textile made from unbleached, and often not fully processed, cotton. It may also contain unseparated husk parts. The fabric is far coarser than muslin, but less coarse and thick than canvas or denim. However, it is still very cheap owing to its unfinished and undyed appearance.

<span class="mw-page-title-main">Textile</span> Various fiber-based materials

Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not the only manufacturing method, and many other methods were later developed to form textile structures based on their intended use. Knitting and non-woven are other popular types of fabric manufacturing. In the contemporary world, textiles satisfy the material needs for versatile applications, from simple daily clothing to bulletproof jackets, spacesuits, and doctor's gowns.

<span class="mw-page-title-main">Tie-dye</span> Technique of resist dyeing

Tie-dye is a term used to describe a number of resist dyeing techniques and the resulting dyed products of these processes. The process of tie-dye typically consists of folding, twisting, pleating, or crumpling fabric or a garment, before binding with string or rubber bands, followed by the application of dye or dyes. The manipulations of the fabric before the application of dye are called resists, as they partially or completely prevent ('resist') the applied dye from coloring the fabric. More sophisticated tie-dye may involve additional steps, including an initial application of dye before the resist, multiple sequential dyeing and resist steps, and the use of other types of resists and discharge.

<span class="mw-page-title-main">Dyeing</span> Process of adding color to textile products

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 the 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.

<span class="mw-page-title-main">Cambric</span> Soft, plain-woven cotton or linen fabric with a lustrous finish

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<span class="mw-page-title-main">Textile manufacturing</span> The industry which produces textiles

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<span class="mw-page-title-main">Textile printing</span> Method for applying patterns to cloth using printing techniques

Textile printing is the process of applying color to fabric in definite patterns or designs. In properly printed fabrics the colour is bonded with the fibre, so as to resist washing and friction. Textile printing is related to dyeing but in dyeing properly the whole fabric is uniformly covered with one colour, whereas in printing one or more colours are applied to it in certain parts only, and in sharply defined patterns.

The manufacture of textiles is one of the oldest of human technologies. To make textiles, the first requirement is a source of fiber from which a yarn can be made, primarily by spinning. The yarn is processed by knitting or weaving, which turns yarn into cloth. The machine used for weaving is the loom. For decoration, the process of colouring yarn or the finished material is dyeing. For more information of the various steps, see textile manufacturing.

<span class="mw-page-title-main">Bleachfield</span> Field near watercourse used by a bleachery

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<span class="mw-page-title-main">Finishing (textiles)</span> Manufacturing process

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<span class="mw-page-title-main">Kier (industrial)</span> Rotating boiler or vat used in bleaching or scouring cotton fabric

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Wet Processing Engineering is one of the major streams in Textile Engineering or Textile manufacturing which refers to the engineering of textile chemical processes and associated applied science. The other three streams in textile engineering are yarn engineering, fabric engineering, and apparel engineering. The processes of this stream are involved or carried out in an aqueous stage. Hence, it is called a wet process which usually covers pre-treatment, dyeing, printing, and finishing.

<span class="mw-page-title-main">Greige goods</span> Woven or knitted fabrics which are not yet dyed or finished.

Greige goods are loom state woven fabrics, or unprocessed knitted fabrics. Greige goods undergo many subsequent processes, for instance, dyeing, printing, bleaching, and finishing, prior to further converting to finished goods such as clothing, or other textile products. "Grey fabrics" is another term to refer to unfinished woven or knitted fabrics.

<span class="mw-page-title-main">Grassing (textiles)</span> Old method of bleaching

Grassing is one of the oldest methods of bleaching textile goods. The grassing method has been long been used in Europe to bleach linen and cotton based fabrics.

<span class="mw-page-title-main">Scouring (textiles)</span> Chemical washing process

Scouring is a preparatory treatment of certain textile materials. Scouring removes soluble and insoluble impurities found in textiles as natural, added and adventitious impurities, for example, oils, waxes, fats, vegetable matter, as well as dirt. Removing these contaminants through scouring prepares the textiles for subsequent processes such as bleaching and dyeing. Though a general term, "scouring" is most often used for wool. In cotton, it is synonymously called "boiling out," and in silk, and "boiling off."

Dunging was a process used in textile manufacturing to finish printed textiles, particularly those printed with aluminium or iron mordants. It was a process of exposing mordanted products into a solution of cow dung and hot water. Dunging was used to fix mordants as well as remove unfixed mordants and thickening agents from the fabric.

Cold pad batch (CPB) is a method of dyeing textiles, typically cellulosic fibers such as cotton, in which the textile is impregnated with dye in a cold state, rather than being heated. High dye fixation and no thermal energy are the advantages of the CPB process. CPB-dyed fabrics are less expensive, have a softer hand feel, and have a cleaner surface than exhaust dyed materials. The process may take up to 12 hours in the batching process, depending on the depth of the shade. The disadvantage is that batching is a time-consuming and lengthy process. The process was developed in 1960.

<span class="mw-page-title-main">Discharge printing</span> Textile printing technique

Discharge printing is a textile printing technique that involves the application of a discharging agent to strip dye from already-dyed cloth in order to produce a printed pattern, which can be either white or colored. It is a method to imprint a design onto dyed fabric. The print pattern is achieved by applying a substance capable of removing the color, such as chlorine or hydrosulfite, to create a white or light pattern on a darker-hued dyed background. A dischargeable dye is employed for dischargeable printing.

In textile processing, stripping is a color removal technique employed to partially or eliminate color from dyed textile materials. Textile dyeing industries often face challenges like uneven or flawed dyeing and the appearance of color patches on the fabric's surface during the dyeing process and subsequent textile material processing stages. Stripping is one of the reprocessing methods used to correct undesirable colors and flaws in dyed materials. The efficacy of this process relies on factors such as the dye type, fiber material, and the stripping agents utilized. Additionally, the procedure is recognized by alternative terms, namely back stripping or destructive stripping.

References

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  2. 1 2 3 4 Hall, A. J. (Archibald John) (1969). The standard handbook of textiles. Internet Archive. New York, Chemical Pub. Co.
  3. ↑ Clark, M. (2011-10-25). Handbook of Textile and Industrial Dyeing: Principles, Processes and Types of Dyes. Elsevier. pp. 65, 66. ISBN   978-0-85709-397-4.
  4. ↑ The Cotton Year Book and Diary. Marsden and Company, Limited. 1919. p. 470.
  5. ↑ "Impurity - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2021-07-31.
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  8. 1 2 Nicholson, Paul T.; Shaw, Ian (2000-03-23). Ancient Egyptian Materials and Technology. citing N Davies "The Tomb of Rekh-mi-re at Thebes" 1943, p.47. Cambridge University Press. p. 280. ISBN   978-0-521-45257-1.
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  10. 1 2 Walton, Perry (1912). The story of textiles. University of California Libraries. Boston, Mass., J. S. Lawrence. pp. 111–115.
  11. 1 2 Crops in peace and war - The yearbook of agriculture 1950 - 1951. U.S. Government Printing Office. 1950. p. 410.
  12. 1 2 Nystrom, Paul Henry (1916). Textiles. D. Appleton. p. 266. Grassing . — The oldest bleaching method is that of "grassing", still used to a certain extent in Europe for bleaching linens . The linen fabrics are laid on the grass or ground for weeks . The oxygen of the air and that given off by green plants
  13. 1 2 Sansone, Antonio (1888). Dyeing: Comprising the Dyeing and Bleaching of Wool, Silk, Cotton, Flax, Hemp, China Grass &c. A. Heywood & son. p. 109.
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  15. 1 2 3 The Encyclopaedia Britannica: A Dictionary of Arts, Sciences, and General Literature: Bleaching. Maxwell Sommerville. 1894. p. 704.
  16. ↑ Davids, Karel (2008-08-31). The Rise and Decline of Dutch Technological Leadership: Technology, Economy and Culture in the Netherlands, 1350-1800. Vol. 1. BRILL. p. 134. ISBN   978-90-474-4332-2.
  17. ↑ Page, Frederick G (2002). "Francis Home and Joseph Black: the Chemistry and Testing of Alkaline Salts in the Early Bleaching and Alkali Trade". Bulletin for the History of Chemistry. 27 (2): 107–113 – via docslib.org.
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  21. ↑ Pickering, Danby (1765). The Statutes at Large 5 - 9 Geo 1 (1718 - 1721). Vol. 14. Cambridge: Joseph Bentham. pp. 318–321.
  22. ↑ Pickering, Danby (1762). Statutes at large 13 - 14 Geo 3 (1773 - 1774). Vol. 30. University of Michigan. Cambridge [London]: Charles Bathurst. p. 437.
  23. ↑ Faculty Of Engineering. p. 18.
  24. ↑ Horrocks, A. Richard; Anand, Subhash C. (2015-12-01). Handbook of Technical Textiles: Technical Textile Processes. Woodhead Publishing. p. 191. ISBN   978-1-78242-481-9.
  25. ↑ Trotman, E. R. (Edward Russell) (1968). Textile scouring and bleaching. Internet Archive. London, Griffin. ISBN   978-0-85264-067-8.
  26. ↑ O'Neill, Charles; Fesquet, A. A. (1869). A dictionary of dyeing and calico printing : containing a brief account of dyeing and printing textile fabrics. University of California Libraries. Philadelphia : H.C. Baird.
  27. ↑ Karmakar, S. R. (1999-11-02). Chemical Technology in the Pre-Treatment Processes of Textiles. Elsevier. ISBN   978-0-08-053947-8.
  28. ↑ "Bleaching Agent - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2021-08-01.
  29. 1 2 The Indian Textile Journal. Indian Textile Journal Limited. 2012. p. 113.
  30. ↑ "Bleaching Agent - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2021-07-27.
  31. ↑ Hage, Ronald; Lienke, Achim (2006). "Applications of Transition-Metal Catalysts to Textile and Wood-Pulp Bleaching". Angewandte Chemie International Edition. 45 (2): 206–222. doi:10.1002/anie.200500525. ISSN   1521-3773. PMID   16342123.
  32. ↑ Smulders, Eduard; Rybinski, Wolfgang von; Sung, Eric; Rähse, Wilfried; Steber, Josef; Wiebel, Frederike; Nordskog, Anette (2007), "Laundry Detergents", Ullmann's Encyclopedia of Industrial Chemistry, American Cancer Society, doi:10.1002/14356007.a08_315.pub2, ISBN   978-3-527-30673-2 , retrieved 2021-08-01
  33. ↑ Colorimetry : understanding the CIE system. János Schanda, International Commission on Illumination. [Vienna, Austria]: CIE/Commission internationale de l'eclairage. 2007. ISBN   978-0-470-17563-7. OCLC   181346337.{{cite book}}: CS1 maint: others (link)
  34. 1 2 Westland, Stephen (2014), "CIE Whiteness", in Luo, Ronnier (ed.), Encyclopedia of Color Science and Technology, Berlin, Heidelberg: Springer, pp. 1–5, doi:10.1007/978-3-642-27851-8_5-1, ISBN   978-3-642-27851-8 , retrieved 2021-08-01
  35. ↑ Amutha, K. (2016-04-05). A Practical Guide to Textile Testing. CRC Press. p. 105. ISBN   978-93-85059-62-9.
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