Stripping (textiles)

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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.

Contents

Right first time

Right-first-time production in textiles entails achieving correctness on the initial dyeing attempt, resulting in a reduced need for stripping, rework, or redyeing. [1]

Stripping is a method of reprocessing employed in the textile industry, wherein the removal of color from fabric becomes essential during the dyeing process. This approach can be employed to rectify any complications encountered during the dyeing process or to alter the color of surplus fabric for subsequent utilization. [2] [3] The stripping process is as complicated as dyeing and requires the greatest care of multiple factors such as dye type, material, reducing agent, cost, etc. [4] When it comes to removing dye from fabric, it is important to distinguish between back stripping and destructive stripping. [5]

Types

Back stripping

Back stripping is a technique employed in the textile industry for the purpose of partial dye removal from fabrics. This method entails the selective extraction or displacement of dye molecules from the textile substrate without causing significant damage to the fabric itself. Back stripping only affects the depth of color. [5] [6] Back stripping primarily relies on the use of appropriate chemicals, solvents, or detergents, often in conjunction with controlled temperature and pH conditions. [2] The objective is to reverse or weaken the chemical bonds that hold the dye molecules to the textile fibers, allowing them to be lifted or washed away. [5] For an example by applying salt and alkali treatment at a temperature of 95 degrees Celsius, a reduction in dye of 20–40% can be achieved in reactive dyed materials. This occurs due to the hydrolysis of the dye fiber bond. [7] This process is generally less aggressive and aims to color correction. [5] [6] [2]

Destructive stripping

Destructive stripping, on the other hand, represents a more aggressive approach to dye removal from fabrics. This method involves the use of harsh chemicals, strong acids. The primary objective of destructive stripping is to completely eliminate the dye molecules. This technique may be employed when the complete removal of the dye takes precedence. Destructive stripping is commonly used where the fabric is to be completely re-dyed. In case of destructive stripping, for example, dyes with an azo group (N=N-) can be chemically reduced to an amine molecule that is almost colorless by using chemical reducing agents. [5] [2] The approach to comprehensive chemical stripping can differ based on the specific dyes applied. [5] There are several methods for carrying out destructive stripping, which can involve reduction alone, oxidation alone, or a combination of both. Another option is to carry out reduction followed by oxidation or oxidation followed by reduction treatment. [7]

Dyes

Direct dyes are removed by either boiling the fabric in alkaline sodium hydrosulfite, bleaching the fabric with sodium hypochlorite, or boiling the fabric with 1–2% sodium chlorite adjusted to a pH of 3 to 4 using formic or acetic acid. [2]

Reactive dyes constitute a significant category of colorants employed in the dyeing process of cellulosic substances like cotton and viscose. [8] Over 80% of the dyes employed in the dyeing of cellulosic materials are reactive dyes. [8] These dyes, as suggested by their name, possess an inherent capacity to chemically react with the hydroxyl groups present in cellulosic materials, resulting in the formation of covalent bonds. Consequently, this chemical reaction imparts excellent fastness properties to the dyed materials. [9] [8]

Vat dyes exhibit resistance to elimination when subjected to reducing chemicals. [4]

To remove certain azoic combinations, 1 gram of Hydrosulfite and 6 cubic centimeters of caustic soda 77Tw [a 32% solution of Sodium Hydroxide] [10] is recommended. [4]

Other factors

Color removal from hydrophilic fibers, which interact well with water, is usually uncomplicated and relies on dyestuff chemistry. Water-soluble agents that react in water often perform the color removal, making the process easy. [11] Dealing with hydrophobic fibers that repel water is more difficult for dyers. They encounter challenges in getting the stripping agent and dyestuff to react in the same environment and must navigate chemical intricacies. [11]

Stripping agents

There are various hydrosulfite compounds that can be used for stripping purposes. [4]

The main ones, excluding sodium hydrosulfite, are: [4]

Ozone

Stripping reactive dyes with ozone is an alternative technique that replaces traditional chemicals, offering a more ecologically sound approach. [12] The resulting wastewater from the ozone stripping process demonstrates a significantly diminished chemical oxygen demand—approximately 97% lower than the effluent produced by conventional stripping methods. [12] The findings of the research study titled 'Application of Ozone in Stripping of Cotton Fabric Dyed with Reactive Dyes' suggest that optimal conditions for color stripping through the ozone method for reactive dyes involve an ozone dose of 10 g/h, an exposure time of 45 minutes, and maintaining a pH level of 5. [12]

Biochemicals

The stripping of certain reactive dyes, such as Black B, can be achieved using five indigenous strains of white rot fungi (WRF), particularly Ganoderma lucidum, in Kirk’s basal salts medium. [13]

Advantages

Textile manufacturers frequently grapple with the challenge of uneven and inadequate dye distribution, which adversely affects the final quality of fabrics. This issue arises from a multitude of underlying factors. [14] Stripping can serve as a reprocessing method aimed at rectifying flawed dyeing. [2]

Color removal is utilized to recover and efficiently utilize discarded materials. [11] The process of stripping color from textile materials serves multiple purposes. It is used to correct uneven and unsuitable dyeing of fibers, yarns, and fabrics. [2] [11] Additionally, it is employed to change the color of dyed textiles to a more desired shade, thereby increasing their marketability. [11]

Textile recycling

The fashion industry exerts a substantial environmental footprint, primarily attributed to the heightened production of textile waste stemming from the proliferation of fast fashion business models. [15] The textile industry, faced with its ever-expanding environmental footprint, is urgently seeking sustainable technologies. It is actively pursuing chemical-based recycling solutions tailored for all primary fiber types, including cellulosic materials like cotton, as well as synthetics such as polyester and nylon. [16]

Completely removing color is a crucial step in the chemical-based recycling process of dyed textile waste. [17] In the realm of textile color removal, two primary methods prevail: dye-destruction and dye-extraction. [17] Yet, both approaches have struggled to achieve sustainable and thorough color removal while preserving the integrity of the polymers involved. Processes like oxidation and photodegradation, which fall under dye-destruction, often result in polymer damage and can lead to changes in the dyeability of regenerated fibers. [17] While dye-extraction is a frequently employed technique in forensic science, it falls short of achieving complete color removal from textiles. [17]

Disadvantages

Stripping is a technique that can potentially lead to a reduction in the strength of the treated materials. Moreover, it exerts a notable influence on production expenses and gives rise to certain environmental and health considerations. [11] [18]

Related Research Articles

<span class="mw-page-title-main">Dye</span> Soluble chemical substance or natural material which can impart color to other materials

A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and may require a mordant to improve the fastness of the dye on the fiber.

<span class="mw-page-title-main">Cellulose acetate</span> Organic compounds which are acetate esters of cellulose

In biochemistry, cellulose acetate refers to any acetate ester of cellulose, usually cellulose diacetate. It was first prepared in 1865. A bioplastic, cellulose acetate is used as a film base in photography, as a component in some coatings, and as a frame material for eyeglasses; it is also used as a synthetic fiber in the manufacture of cigarette filters and playing cards. In photographic film, cellulose acetate film replaced nitrate film in the 1950s, being far less flammable and cheaper to produce.

<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 like fibers, yarns, and fabrics

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.

Desizing is the process of removing the size material from warp yarns after a textile fabric is woven.

In a reactive dye, a chromophore contains a substituent that reacts with the substrate. Reactive dyes have good fastness properties owing to the covalent bonding that occurs during dyeing. Reactive dyeing is the most important method for coloring cellulose fibers. Reactive dyes can also be applied on wool and nylon; in the latter case they are applied under weakly acidic conditions. Reactive dyes have a low utilization degree compared to other types of dyestuff, since the functional group also bonds to water, creating hydrolysis.

Vat dyes are a class of dyes that are classified as such because of the method by which they are applied. Vat dyeing is a process that refers to dyeing that takes place in a bucket or vat. The original vat dye is indigo, once obtained only from plants but now often produced synthetically.

<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.

<span class="mw-page-title-main">Textile bleaching</span> Textile wet process that improves whiteness by removing natural color

The textile bleaching 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. 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.

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

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. The precise meaning depends on context.

<span class="mw-page-title-main">Lightfastness</span> Ability of a colorant or material to withstand change due to light exposure

Lightfastness is a property of a colourant such as dye or pigment that describes its resistance to fading when exposed to light. Dyes and pigments are used for example for dyeing of fabrics, plastics or other materials and manufacturing paints or printing inks.

<span class="mw-page-title-main">Natural dye</span> Dye extracted from plant or animal sources

Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources—roots, berries, bark, leaves, and wood—and other biological sources such as fungi.

<span class="mw-page-title-main">Glossary of dyeing terms</span>

Dyeing is the craft of imparting colors to textiles in loose fiber, yarn, cloth or garment form by treatment with a dye. Archaeologists have found evidence of textile dyeing with natural dyes dating back to the Neolithic period. In China, dyeing with plants, barks and insects has been traced back more than 5,000 years. Natural insect dyes such as Tyrian purple 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. Synthetic dyes quickly superseded natural dyes for the large-scale commercial textile production enabled by the industrial revolution, but natural dyes remained in use by traditional cultures around the world.

Colour fastness is a term—used in the dyeing of textile materials—that characterizes a material's colour's resistance to fading or running. Colour fastness is the property of dyes and it is directly proportional to the binding force between photochromic dye and the fibre. The colour fastness may also be affected by processing techniques and choice of chemicals and auxiliaries.

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.

Green textiles are fabrics or fibres produced to replace environmentally harmful textiles and minimise the ecological impact. Green textiles are part of the sustainable fashion and eco-friendly trends, providing alternatives to the otherwise pollution-heavy products of conventional textile industry, which is deemed the most ecologically damaging industry.

<span class="mw-page-title-main">Textile stabilization</span> A conservation method

Textile stabilization is a conservation method for fiber and yarn-based cloth intended to mitigate damage, prevent degradation and preserve structural integrity. Stabilization is part of a broad set of techniques in the field of conservation and restoration of textiles typically undertaken by a specialist or textile conservator. Appropriate treatment is determined through risk assessment and close examination of a textile's characteristics and the nature of the damage. Organic and synthetic fibers become weak due to age, handling, and environmental exposure and display physical deterioration such as fraying, planar distortion, loss, and change in surface character. Treatment involves reinforcing tensile strength and reintegration of parts for aesthetic, functional, and historic preservation. Methods can include stitching, darning, reweaving, and the attachment of supports through overlays and underlays. Hand-sewing follows the mantra of “gently does it” using fine needles, supple yarns, and a light touch. Heavily damaged and fragile fabrics often require stabilization through adhesive consolidation, though this is less common. It is essential that conservators consider physical and chemical compatibility along with future treatability in choosing a stabilization technique.

Cationization of cotton is an electro kinetic phenomena for surface charge of cotton. The cotton surface is charged with positive ions. Cationization alters the characterization of the surface of the cotton which allows salt free dyeing and improves the dye ability of cotton. The process involves the chemical reaction of cationic reactive agents with cellulose.

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.

References

  1. ↑ Kadolph, Sara J. (1998). Textiles. Internet Archive. Upper Saddle River, N.J. : Merrill. p. 370. ISBN   978-0-13-494592-7.
  2. 1 2 3 4 5 6 7 US 4227881,Fono, Andrew,"New process of color stripping dyed textile fabric",published 1980-10-14, assigned to Royce Chemical Co.
  3. ↑ Uddin, Mohammad Gias; Islam, Md. Mazedul; Islam, Md. Rashedul (2015-06-24). "Effects of reductive stripping of reactive dyes on the quality of cotton fabric". Fashion and Textiles. 2 (1): 8. doi: 10.1186/s40691-015-0032-y . hdl: 10536/DRO/DU:30096333 . ISSN   2198-0802.
  4. 1 2 3 4 5 6 Stabkie, J. (1947). "The Stripping of Dyed Textiles by the Use of Hydrosulphite Compounds" . Journal of the Society of Dyers and Colourists. 63 (11): 340–343. doi:10.1111/j.1478-4408.1947.tb02435.x. ISSN   0037-9859.
  5. 1 2 3 4 5 6 Uddin, Mohammad Gias; Islam, Md. Mazedul; Islam, Md. Rashedul (2015-06-24). "Effects of reductive stripping of reactive dyes on the quality of cotton fabric". Fashion and Textiles. 2 (1): 8. doi: 10.1186/s40691-015-0032-y . hdl: 10536/DRO/DU:30096333 . ISSN   2198-0802. S2CID   55576972.
  6. 1 2 Chatha, Shahzad Ali Shahid; Asgher, Muhammad; Ali, Shaukat; Hussain, Abdullah Ijaz (2012-01-15). "Biological color stripping: A novel technology for removal of dye from cellulose fibers" . Carbohydrate Polymers. 87 (2): 1476–1481. doi:10.1016/j.carbpol.2011.09.041. ISSN   0144-8617.
  7. 1 2 Aspland, J. Richard (1997). Textile Dyeing and Coloration. AATCC. p. 130. ISBN   978-0-9613350-1-4.
  8. 1 2 3 Raja, A. S. M.; Arputharaj, A.; Krishnaprasad, G.; Saxena, Sujata; Patil, P. G. (2021-01-01), Muthu, Subramanian Senthilkannan (ed.), "4 - Challenges in dyeing of cellulosics with reactive dyes and practical sustainable feasibilities", Chemical Management in Textiles and Fashion, The Textile Institute Book Series, Woodhead Publishing, pp. 79–98, ISBN   978-0-12-820494-8 , retrieved 2023-08-20
  9. ↑ Dockery, C. R.; Stefan, A. R.; Nieuwland, A. A.; Roberson, S. N.; Baguley, B. M.; Hendrix, J. E.; Morgan, S. L. (2009-06-18). "Automated extraction of direct, reactive, and vat dyes from cellulosic fibers for forensic analysis by capillary electrophoresis". Analytical and Bioanalytical Chemistry. 394 (8): 2095–2103. doi:10.1007/s00216-009-2876-8. ISSN   1618-2642. PMID   19536528. S2CID   20678951.
  10. ↑ https://www.murphyandson.co.uk/wp-content/uploads/2018/09/Caustic-Soda-70TW-TDS-2018.pdf
  11. 1 2 3 4 5 6 American Dyestuff Reporter 1953-03-30: Vol 42 Iss 7. Internet Archive. American Association of Textile Chemists and Colorists. 1953-03-30. p. 190.{{cite book}}: CS1 maint: others (link)
  12. 1 2 3 Arooj, Fariha; Ahmed, Nasir; Shaikh, Irfan Ahmed (2020-07-03). "Application of Ozone in Stripping of Cotton Fabric Dyed with Reactive Dyes" . Ozone: Science & Engineering. 42 (4): 319–330. doi:10.1080/01919512.2019.1667750. ISSN   0191-9512. S2CID   204137290.
  13. ↑ Chatha, Shahzad AS; Ali, Shoukat; Asgher, Muhammad; Haq Nawaz Bhatti (2011). "Investigation of the potential of microbial stripping of dyed cotton fabric using white rot fungi" . Textile Research Journal. 81 (17): 1762–1771. doi:10.1177/0040517511411973. ISSN   0040-5175. S2CID   101738296.
  14. ↑ Latif, Zainab; Shafique, Javeria; Summuna, Baby; Lone, Bashir; ur Rehman, Munib; El-Sheikh, Mohamed A.; Hashim, Maha J.; Vladulescu, Carmen; Shafique, Tahira (2021). "Development of efficient strain of Ganoderma lucidum for biological stripping of cotton fabric dyed Reactive Blue 21". Saudi Journal of Biological Sciences. 28 (12): 7550–7560. doi:10.1016/j.sjbs.2021.09.038. PMC   8626342 . PMID   34867059.
  15. ↑ Sanchis-Sebastiá, Miguel; Ruuth, Edvin; Stigsson, Lars; Galbe, Mats; Wallberg, Ola (2021-02-15). "Novel sustainable alternatives for the fashion industry: A method of chemically recycling waste textiles via acid hydrolysis". Waste Management. 121: 248–254. Bibcode:2021WaMan.121..248S. doi: 10.1016/j.wasman.2020.12.024 . ISSN   0956-053X. PMID   33388647. S2CID   230487189.
  16. ↑ Alex Scott (2022-03-28). "Transforming textiles". C&EN Global Enterprise. 100 (11): 22–28. doi:10.1021/cen-10011-cover. ISSN   2474-7408.
  17. 1 2 3 4 Mu, Bingnan; Yang, Yiqi (2022-01-01). "Complete separation of colorants from polymeric materials for cost-effective recycling of waste textiles". Chemical Engineering Journal. 427: 131570. doi: 10.1016/j.cej.2021.131570 . ISSN   1385-8947.
  18. ↑ Tayyaba, Noor; Younas, Touseef; Ali, Shaukat (2021). "Chemical Color Stripping of Cellulose Fabric dyed with Reactive dyes" (PDF). International Journal of Science and Innovative Research. 2 (5): 416. ISSN   2724-3338.
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