Textile finishing machinery, Red Bridge Mills, Ainsworth, 1983
Textile finishing machinery, Red Bridge Mills, Ainsworth, 1983

In textile manufacturing, finishing refers to the processes that convert the woven or knitted cloth into a usable material and more specifically to any process performed after dyeing the yarn or fabric to improve the look, performance, or "hand" (feel) of the finish textile or clothing.[1][2] The precise meaning depends on context.

Fabric after leaving the loom or knitting machine is not readily useable. Called grey cloth at this stage, it contains natural and added impurities. Sometimes it is also processed at fiber or yarn stages of textile manufacturing. Grey fiber or yarn or fabric goes through a series of processes such as wet processing and finishing. Finishing is a broad range of physical and chemical treatments that complete one stage of textile manufacturing and may prepare for the next step, making the product more receptive to the next stage of manufacturing. Finishing adds value to the product and makes it more attractive, useful, and functional for the end-user. Improving surface feel, aesthetics, and addition of advanced chemical finishes are some examples of textile finishing.[3]

Some finishing techniques such as bleaching and dyeing are applied to yarn before it is woven while others are applied to the grey cloth directly after it is woven or knitted.[4] Some finishing techniques, such as fulling, became outdated with the industrial revolution while others, such as mercerisation, are developments following the Industrial Revolution.

Introduction

In order to impart the required functional properties to the fiber or fabric, it is customary to subject the material to different types of physical and chemical treatments. For example, wash and wear finish for a cotton fabric is necessary to make it crease-free or wrinkle-free. In a similar way, mercerising, singeing, flame retardant, water repellent, waterproof, anti-static and peach finishing achieve various fabric properties desired by consumers.

The use of 100% synthetic textiles has increased considerably since the development of textured yarns made of filaments and the growing production of knit goods. The use of open weave has enabled the production of lighter, breathable, fabrics to ensure better wearing comfort.

The properties of petroleum-based synthetic fibers, most important among them being polyamide, polyester and polyacrylonitrile, are essentially different from those of natural cellulosic and protein-based (wool) fibers. Hence the sequence of finishing operations is likely to be different. While cellulosic fabrics require a resin finishing treatment to impart easy-care properties, synthetic fibers already exhibit these easy-care criteria and require only a heat setting operation.

Finishing of cotton

Purification and preliminary processes

The grey cloth—woven cotton fabric in its loom-state—not only contains impurities, including warp size, but requires further treatment in order to develop its full textile potential. Furthermore, it may receive considerable added value by applying one or more finishing processes.[5][6]

Singeing

Main article: Singeing (textiles)

Singeing is a preparation method of textiles; it is applied more commonly to woven textiles and cotton yarns. Singeing in textiles is a mechanical treatment or finish to obtain a neat surface of the fabric or less hairy yarn. In a singeing machine, the yarns or fabrics are exposed to direct flames to burn the protruding fibers of the textile materials. Hence, also called "gassing".[7][8][9][10]

Desizing

Main article: Desizing

Depending on the size that has been used, the cloth may be steeped in a dilute acid and then rinsed, or enzymes may be used to break down the size.[10]

Scouring

Main article: Scouring (textiles)

Scouring is a chemical washing process carried out on cotton fabric to remove natural wax and non-fibrous impurities (e.g. the remains of seed fragments) from the fibres and any adventitious oil, soiling or dirt. Scouring was used to carry in iron vessels called kiers. The fabric was boiled in an alkali, which forms a soap with free fatty acids (saponification). A kier is usually enclosed, so the solution of sodium hydroxide can be boiled under pressure, excluding oxygen which would degrade the cellulose in the fibre. If the appropriate reagents are used, scouring will also remove size from the fabric although desizing often precedes scouring and is considered to be a separate process known as fabric preparation. Preparation and scouring are prerequisites to most of the other finishing processes. At this stage even the most naturally white cotton fibres are yellowish, and bleaching, the next process, is required.[10]

Bleaching

Main article: Textile bleaching

Bleaching improves whiteness by removing natural coloration and remaining trace impurities from the cotton; the degree of bleaching necessary is determined by the required whiteness and absorbency. Cotton being a vegetable fibre will be bleached using an oxidizing agent, such as dilute sodium hypochlorite or dilute hydrogen peroxide. If the fabric is to be dyed a deep shade, then lower levels of bleaching are acceptable, for example. However, for white bed sheetings and medical applications, the highest levels of whiteness and absorbency are essential.[11]

Mercerising

Main article: Mercerized cotton

A further possibility is mercerizing, during which the fabric is treated with a caustic soda solution to cause swelling of the fibres. This results in improved luster, strength, and dye affinity. Cotton is mercerized under tension, and all alkali must be washed out before the tension is released or shrinkage will take place. Mercerizing can take place directly on grey cloth, or after bleaching.[12]

Coloration

Color is a sensation caused when white light from a source such as the sun is reflected off a pigment on the surface. The pigment selectively reflects certain wavelengths of light while absorbing others. A dye can be considered as a substance that can be fixed to a material that has these properties. The colour it reflects is defined by the structure of the molecule, and particularly the parts of the chromogen molecule called the chromophore group. [13] There are two processes used to apply colour:

Dyeing

Main article: Dyeing

Cotton is an absorbent fibre which responds readily to colouration processes. Dyeing is commonly carried out with an anionic direct dye by completely immersing the fabric (or yarn) in an aqueous dyebath according to a prescribed procedure. For improved fastness to washing, rubbing, and light, other dyes such as vats and reactives are commonly used. These require more complex chemistry during processing and are thus more expensive to apply.[14]

Printing

Main article: Textile printing

Printing is the application of colour in the form of a paste or ink to the surface of a fabric, in a predetermined pattern. It may be considered as localised dyeing. Printing designs on to already dyed fabric is also possible. The common processes are block printing, roller printing and screen printing

Finishing

Mechanical finishing

Mechanical finish refers to machine finishes such as embossing, heat setting, sanforizing, sheering, various, luster imparting, surface finishes, and glaze finishes.[15][16]

Mechanical Finishes[16]
Raised surface finishes Luster imparting Glaze and design
Gigging Calendering Embossing
Napping Beetling Moire
 Sueding
Flocking
Raising

Main article: Gig-mill

Another finishing process is raising. During raising, the fabric surface is treated with sharp teeth to lift the surface fibres, thereby imparting hairiness, softness, and warmth, as in flannelette.

Shearing

Main article: Shearing (textiles)

Shearing is a kind of mechanical finish in which the appearance of the fabric is enhanced by cutting the loops or raised surface to a uniform and even height. The machine may have a spiral blade similar to a grass cutting machine.[17][18] A Shearing machine can cut the loop or the pile to a desired level.[19]

Peaching

Peaching is also a mechanical finish comparable to raising but very gentle. The peach effect on fabrics is obtained by sanding the fabrics slightly; it imparts a protruded surface and soft feel. The peaching finish is also possible with certain chemicals or laundry abrasion.[20]

Calendering

Main article: Calendering

Calendering is the third important mechanical process, in which the fabric is passed between heated rollers to generate smooth, polished or embossed effects depending on roller surface properties and relative speeds.[21]

Chemical finishing

Many other chemical treatments may be applied to cotton fabrics to produce low flammability, crease resist and other special effects.

Shrinking

Main article: Sanforization

Main article: Dimensional stability (fabric)

Mechanical shrinking (sometimes referred to as sanforizing), whereby the fabric is forced to shrink width and/or lengthwise, creates a fabric in which any residual tendency to shrink after subsequent laundering is minimal. [22] Fibers to fabric conversion lead to many mechanical tensions and forces during manufacturing, which includes following steps for fibre to yarn conversion with spinning then fabric with weaving, and knitting. When the products are immersed in water, the water acts as a relaxing medium and all stresses and strains get relaxed and try to come back to its original relaxed state. Even after finishing with sophisticated finishing machines, some residual shrinkage remains, which is carried forward to the garment stage. This residual shrinkage may cause deformity or de-shaping of the products after domestic laundry. There are certain acceptance limits of shrinkage levels for every product. Abnormal shrinkage levels are considered a non-conformity to quality standards.

Standard finishes

Quality-oriented

Design-oriented

Handle-oriented

Special finishes for natural fibers

Special finishes for synthetic fibers

See also

References

  1. ^ Collier 1970, p. 154.
  2. ^ Kadolph 2007, pp. 330–341.
  3. ^ Principles of Textile Finishing. Woodhead. 29 April 2017. pp. 1–10. ISBN 9780081006610.
  4. ^ Collier 1970, p. 246.
  5. ^ "Finishing", Spinning the Web, Manchester City Council: Libraries, retrieved 2009-01-29
  6. ^ GREENHALGH, DAVID (2005), Cotton finishing, retrieved 2009-02-12
  7. ^ Kadolph 2007, p. 334.
  8. ^ Tortora, Phyllis G.; Johnson, Ingrid (2013-09-17). The Fairchild Books Dictionary of Textiles. A&C Black. p. 564. ISBN 978-1-60901-535-0.
  9. ^ Adanur, Sabit (1995-10-06). Wellington Sears Handbook of Industrial Textiles. CRC Press. p. 162. ISBN 978-1-56676-340-0.
  10. ^ a b c Collier 1970, p. 155
  11. ^ Collier 1970, p. 157
  12. ^ Collier 1970, p. 159
  13. ^ Collier 1970, p. 160
  14. ^ Collier 1970, p. 161
  15. ^ Schindler, W. D.; Hauser, P. J. (2004-08-10). Chemical Finishing of Textiles. Elsevier. pp. 1, 2. ISBN 978-1-84569-037-3.
  16. ^ a b Joseph, Marjory L. (1992). Joseph's introductory textile science. Internet Archive. Fort Worth : Harcourt Brace Jovanovich College Publishers. pp. 337, 338, 339, 340. ISBN 978-0-03-050723-6.
  17. ^ Elsasser, Virginia Hencken (2005). Textiles : concepts and principles. Internet Archive. New York, NY : Fairchild Publications. p. 197. ISBN 978-1-56367-300-9.
  18. ^ Joseph, Marjory L. (1992). Joseph's introductory textile science. Internet Archive. Fort Worth : Harcourt Brace Jovanovich College Publishers. p. 392. ISBN 978-0-03-050723-6.
  19. ^ Purushothama, B. (2019-01-31). Handbook of Value Addition Processes for Fabrics. Woodhead Publishing India PVT. Limited. p. 243. ISBN 978-93-85059-92-6.
  20. ^ "Product Guides - Glossary". web.archive.org. 2012-05-10. Retrieved 2020-10-27.
  21. ^ Collier 1970, p. 172
  22. ^ Collier 1970, p. 175
  23. ^ Roy Choudhury, Asim Kumar (2017). Principles of textile finishing. Elsevier Science. p. 55. ISBN 9780081006610.
  24. ^ Iyigundogdu, Zeynep Ustaoglu; Demir, Okan; Asutay, Ayla Burcin; Sahin, Fikrettin (2017). "Developing Novel Antimicrobial and Antiviral Textile Products". Applied Biochemistry and Biotechnology. 181 (3): 1155–1166. doi:10.1007/s12010-016-2275-5. PMC 7091037. PMID 27734286.
  25. ^ Wu, Deyong; Long, Mingce (2011-12-28). "Realizing Visible-Light-Induced Self-Cleaning Property of Cotton through Coating N-TiO2 Film and Loading AgI Particles". ACS Applied Materials & Interfaces. 3 (12): 4770–4774. doi:10.1021/am201251d. ISSN 1944-8244. PMID 22066707.
  26. ^ "Self-cleaning cotton nanoparticle coating invented". BBC News. 2012-03-08. Retrieved 2020-10-05.

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