View source for Stripping (textiles)

{{Short description|Color removal technique in textiles}}
{{Other uses|Strip (disambiguation){{!}}Strip}}
In textile processing, '''stripping''' is a color removal technique employed to partially or eliminate [[Color of clothing|color]] from [[Dyeing|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 [[Reducing agent|stripping agents]] utilized. Additionally, the procedure is recognized by alternative terms, namely '''back stripping''' or '''destructive stripping'''.

== 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.<ref>{{Cite book |last=Kadolph |first=Sara J. |url=http://archive.org/details/textiles0000kado |title=Textiles |date=1998 |location=Upper Saddle River, N.J.  |publisher= Merrill |isbn=978-0-13-494592-7 |pages=370}}</ref>

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.<ref name=":1">{{Cite patent|number=4227881|title=New process of color stripping dyed textile fabric|pubdate=1980-10-14|inventor1-last=Fono|inventor1-first=Andrew|country=US|assign1=Royce Chemical Co.}}</ref><ref>{{Cite journal |last1=Uddin |first1=Mohammad Gias |last2=Islam |first2=Md. Mazedul |last3=Islam |first3=Md. Rashedul |date=2015-06-24 |title=Effects of reductive stripping of reactive dyes on the quality of cotton fabric |journal=Fashion and Textiles |language=en |volume=2 |issue=1 |pages=8 |doi=10.1186/s40691-015-0032-y |issn=2198-0802 |doi-access=free|hdl=10536/DRO/DU:30096333 |hdl-access=free }}</ref>  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.<ref name=":8" /> When it comes to removing dye from fabric, it is important to distinguish between back stripping and destructive stripping.<ref name=":0">{{Cite journal |last1=Uddin |first1=Mohammad Gias |last2=Islam |first2=Md. Mazedul |last3=Islam |first3=Md. Rashedul |date=2015-06-24 |title=Effects of reductive stripping of reactive dyes on the quality of cotton fabric |journal=Fashion and Textiles |language=en |volume=2 |issue=1 |pages=8 |doi=10.1186/s40691-015-0032-y |issn=2198-0802 |s2cid=55576972 |doi-access=free |hdl-access=free |hdl=10536/DRO/DU:30096333}}</ref>

== 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.<ref name=":0" /><ref name=":4">{{Cite journal |last1=Chatha |first1=Shahzad Ali Shahid |last2=Asgher |first2=Muhammad |last3=Ali |first3=Shaukat |last4=Hussain |first4=Abdullah Ijaz |date=2012-01-15 |title=Biological color stripping: A novel technology for removal of dye from cellulose fibers |url=https://www.sciencedirect.com/science/article/pii/S0144861711008241 |journal=Carbohydrate Polymers |volume=87 |issue=2 |pages=1476–1481 |doi=10.1016/j.carbpol.2011.09.041 |issn=0144-8617|url-access=subscription }}</ref> Back stripping primarily relies on the use of appropriate chemicals, solvents, or detergents, often in conjunction with controlled temperature and pH conditions.<ref name=":1" />  The objective is to reverse or weaken the [[chemical bond]]s that hold the dye molecules to the textile fibers, allowing them to be lifted or washed away.<ref name=":0" /> 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.<ref name=":5">{{Cite book |last=Aspland |first=J. Richard |url=https://books.google.com/books?id=5fMBJZ8NPcgC&dq=stripping+reactive+dyes+cotton&pg=PA130 |title=Textile Dyeing and Coloration |date=1997 |publisher=AATCC |isbn=978-0-9613350-1-4 |pages=130 |language=en}}</ref> This process is generally less aggressive and aims to color correction.<ref name=":0" /><ref name=":4" /><ref name=":1" />

=== 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 compound|azo group]] (N=N-) can be chemically reduced to an [[amine]] molecule that is almost colorless by using chemical reducing agents.<ref name=":0" /><ref name=":1" /> The approach to comprehensive chemical stripping can differ based on the specific dyes applied.<ref name=":0" /> 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.<ref name=":5" />

==== Dyes ====
[[Substantive dye|Direct dyes]] are removed by either boiling the fabric in alkaline [[Sodium dithionite|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]].<ref name=":1" />

[[Reactive dye]]s constitute a significant category of colorants employed in the dyeing process of cellulosic substances like cotton and viscose.<ref name=":7">{{Citation |last1=Raja |first1=A. S. M. |title=4 - Challenges in dyeing of cellulosics with reactive dyes and practical sustainable feasibilities |date=2021-01-01 |url=https://www.sciencedirect.com/science/article/pii/B9780128204948000046 |work=Chemical Management in Textiles and Fashion |pages=79–98 |editor-last=Muthu |editor-first=Subramanian Senthilkannan |access-date=2023-08-20 |series=The Textile Institute Book Series |publisher=Woodhead Publishing |isbn=978-0-12-820494-8 |last2=Arputharaj |first2=A. |last3=Krishnaprasad |first3=G. |last4=Saxena |first4=Sujata |last5=Patil |first5=P. G.}}</ref> Over 80% of the dyes employed in the dyeing of cellulosic materials are reactive dyes.<ref name=":7" /> 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 bond]]s. Consequently, this chemical reaction imparts excellent fastness properties to the dyed materials.<ref name=":6">{{Cite journal |last1=Dockery |first1=C. R. |last2=Stefan |first2=A. R. |last3=Nieuwland |first3=A. A. |last4=Roberson |first4=S. N. |last5=Baguley |first5=B. M. |last6=Hendrix |first6=J. E. |last7=Morgan |first7=S. L. |date=2009-06-18 |title=Automated extraction of direct, reactive, and vat dyes from cellulosic fibers for forensic analysis by capillary electrophoresis |url=http://dx.doi.org/10.1007/s00216-009-2876-8 |journal=Analytical and Bioanalytical Chemistry |volume=394 |issue=8 |pages=2095–2103 |doi=10.1007/s00216-009-2876-8 |issn=1618-2642 |pmid=19536528 |s2cid=20678951}}</ref><ref name=":7" />

[[Vat dye]]s exhibit resistance to elimination when subjected to reducing chemicals.<ref name=":8">{{Cite journal |last=Stabkie |first=J. |date=1947 |title=The Stripping of Dyed Textiles by the Use of Hydrosulphite Compounds |url=http://dx.doi.org/10.1111/j.1478-4408.1947.tb02435.x |journal=Journal of the Society of Dyers and Colourists |volume=63 |issue=11 |pages=340–343 |doi=10.1111/j.1478-4408.1947.tb02435.x |issn=0037-9859|url-access=subscription }}</ref>

To remove certain azoic combinations, 1 gram of Hydrosulfite and 6 cubic centimeters of caustic soda 77Tw [a 32% solution of Sodium Hydroxide]<ref>https://www.murphyandson.co.uk/wp-content/uploads/2018/09/Caustic-Soda-70TW-TDS-2018.pdf</ref> is recommended.<ref name=":8" />

===== 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.<ref name=":2">{{Cite book |url=http://archive.org/details/sim_american-dyestuff-reporter_1953-03-30_42_7 |title=American Dyestuff Reporter 1953-03-30: Vol 42 Iss 7 |date=1953-03-30 |publisher=American Association of Textile Chemists and Colorists |pages=190 |language=English}}</ref> 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.<ref name=":2" />

== Stripping agents ==
There are various hydrosulfite compounds that can be used for stripping purposes.<ref name=":8" />

The main ones, excluding sodium hydrosulfite, are:<ref name=":8" />

* Zinc Formosul (Br) or Decroline (TG) is an insoluble basic zinc sulphoxylate-formaldehyde.
* Formosul (Br) or Rongalite C (IG) is a water-soluble sodium sulphoxylate-formaldehyde.
* Redusol Z (Br) or Decroline Soluble Conc. (IG) is a water-soluble neutral zinc sulphoxylate-formaldehyde.<ref name=":8" />

=== Ozone ===
Stripping reactive dyes with ozone is an alternative technique that replaces traditional chemicals, offering a more ecologically sound approach.<ref name=":3">{{Cite journal |last1=Arooj |first1=Fariha |last2=Ahmed |first2=Nasir |last3=Shaikh |first3=Irfan Ahmed |date=2020-07-03 |title=Application of Ozone in Stripping of Cotton Fabric Dyed with Reactive Dyes |url=https://www.tandfonline.com/doi/full/10.1080/01919512.2019.1667750 |journal=Ozone: Science & Engineering |language=en |volume=42 |issue=4 |pages=319–330 |doi=10.1080/01919512.2019.1667750 |s2cid=204137290 |issn=0191-9512|url-access=subscription }}</ref> 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.<ref name=":3" /> 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.<ref name=":3" />

=== 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.<ref>{{Cite journal |last1=Chatha |first1=Shahzad AS |last2=Ali |first2=Shoukat |last3=Asgher |first3=Muhammad |last4=Haq Nawaz Bhatti |date=2011 |title=Investigation of the potential of microbial stripping of dyed cotton fabric using white rot fungi |url=http://journals.sagepub.com/doi/10.1177/0040517511411973 |journal=Textile Research Journal |language=en |volume=81 |issue=17 |pages=1762–1771 |doi=10.1177/0040517511411973 |s2cid=101738296 |issn=0040-5175|url-access=subscription }}</ref>

== 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.<ref>{{Cite journal |last1=Latif |first1=Zainab |last2=Shafique |first2=Javeria |last3=Summuna |first3=Baby |last4=Lone |first4=Bashir |last5=ur Rehman |first5=Munib |last6=El-Sheikh |first6=Mohamed A. |last7=Hashim |first7=Maha J. |last8=Vladulescu |first8=Carmen |last9=Shafique |first9=Tahira |date=2021 |title=Development of efficient strain of Ganoderma lucidum for biological stripping of cotton fabric dyed Reactive Blue 21 |journal=Saudi Journal of Biological Sciences |language=en |volume=28 |issue=12 |pages=7550–7560 |doi=10.1016/j.sjbs.2021.09.038|pmid=34867059 |pmc=8626342 }}</ref> Stripping can serve as a reprocessing method aimed at rectifying flawed dyeing.<ref name=":1" />

Color removal is utilized to recover and efficiently utilize discarded materials.<ref name=":2" /> 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.<ref name=":1" /><ref name=":2" /> Additionally, it is employed to change the color of dyed textiles to a more desired shade, thereby increasing their marketability.<ref name=":2" />

=== 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.<ref>{{Cite journal |last1=Sanchis-Sebastiá |first1=Miguel |last2=Ruuth |first2=Edvin |last3=Stigsson |first3=Lars |last4=Galbe |first4=Mats |last5=Wallberg |first5=Ola |date=2021-02-15 |title=Novel sustainable alternatives for the fashion industry: A method of chemically recycling waste textiles via acid hydrolysis |journal=Waste Management |volume=121 |pages=248–254 |doi=10.1016/j.wasman.2020.12.024 |pmid=33388647 |bibcode=2021WaMan.121..248S |s2cid=230487189 |issn=0956-053X|doi-access=free }}</ref> The textile industry, faced with its ever-expanding environmental footprint, is urgently seeking sustainable technologies. It is actively pursuing [[Textile recycling|chemical-based recycling]] solutions tailored for all primary fiber types, including cellulosic materials like cotton, as well as synthetics such as polyester and nylon.<ref>{{Cite journal |last=Alex Scott |date=2022-03-28 |title=Transforming textiles |url=https://pubs.acs.org/doi/10.1021/cen-10011-cover |journal=C&EN Global Enterprise |language=en |volume=100 |issue=11 |pages=22–28 |doi=10.1021/cen-10011-cover |issn=2474-7408|doi-access=free }}</ref>

Completely removing color is a crucial step in the chemical-based recycling process of dyed textile waste.<ref name=":9">{{Cite journal |last1=Mu |first1=Bingnan |last2=Yang |first2=Yiqi |date=2022-01-01 |title=Complete separation of colorants from polymeric materials for cost-effective recycling of waste textiles |journal=Chemical Engineering Journal |volume=427 |pages=131570 |doi=10.1016/j.cej.2021.131570 |issn=1385-8947|doi-access=free }}</ref> In the realm of textile color removal, two primary methods prevail: dye-destruction and dye-extraction.<ref name=":9" /> 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.<ref name=":9" /> While dye-extraction is a frequently employed technique in forensic science, it falls short of achieving complete color removal from textiles.<ref name=":9" />

=== 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.<ref name=":2" /><ref>{{cite journal |last1=Tayyaba |first1=Noor |last2=Younas |first2=Touseef |last3=Ali |first3=Shaukat |title=Chemical Color Stripping of Cellulose Fabric dyed with Reactive dyes |journal=International Journal of Science and Innovative Research |date=2021 |volume=2 |issue=5 |pages=416 |issn=2724-3338|url=https://ijesir.org/wp-content/uploads/2021/ppp0100044IJESIR.pdf}}</ref>

== References ==
{{Reflist}}
{{Dyeing}}
{{Textile arts}}
{{Fabric}}

[[Category:Textile arts]]
[[Category:Textile techniques]]
[[Category:Textile treatments]]