Retting

{{Short description|Isolating plant fiber by rotting all else}} {{more citations needed|date=November 2011}} thumb|Flax being laid out in a field for dew retting, {{circa|1915-1918}}

'''Retting''' is a textile process for separating the bast fibre in plants from the non-fibrous materials to create fibers that can be spun into yarn.<ref name="linen">{{cite journal | last = Akin | first = Danny E. | title = Linen Most Useful: Perspectives on Structure, Chemistry, and Enzymes for Retting Flax | journal = ISRN Biotechnology | publisher = Hindawi Publishing Corporation | year = 2013 | volume = 2013 | pages = 1–23 | doi = 10.5402/2013/186534 | pmid = 25969769 | pmc = 4403609 | doi-access = free }}</ref><ref name="cellulose">{{cite journal | last1 = Manian | first1 = A. P. | last2 = Cordin | first2 = M. | last3 = Pham | first3 = T. | title = Extraction of cellulose fibers from flax and hemp: a review | journal = Cellulose | volume = 28 | issue = 15 | pages = 8275–8294 | doi = 10.1007/s10570-021-04051-x | url = https://doi.org/10.1007/s10570-021-04051-x | publisher = Springer | date = September 2021 | orig-date = 12 July 2021| doi-access = free }}</ref> The separation is primarily achieved through either a microbial or chemical action degradating the cementing compounds that bind the bast fibres to other plant tissues, allowing the fibers to be isolated.<ref name="linen"></ref><ref name="ramie">{{cite journal | last1 = Angelini | first1 = Luciana G. | last2 = Scalabrelli | first2 = Mattia | last3 = Tavarini | first3 = Silvia | last4 = Cinelli | first4 = Patrizia | last5 = Anguillesi | first5 = Irene | last6 = Lazzeri | first6 = Andrea | title = Ramie fibers in a comparison between chemical and microbiological retting proposed for application in biocomposites | journal = Industrial Crops and Products | volume = 75 | year = 2015 | pages = 178–184 | doi = 10.1016/j.indcrop.2015.05.004 | url = https://doi.org/10.1016/j.indcrop.2015.05.004 |access-date=2025-12-01 | hdl = 11568/755116 | hdl-access = free }}</ref> Retting can be used to create fibers from plants such as flax, hemp, nettles, ramie, bamboo, and jute.<ref name="hemp">{{cite journal | last1 = Lavrieux | first1 = Marlène | last2 = Jacob | first2 = Jérémy | last3 = Disnar | first3 = Jean-Robert | last4 = Bréheret | first4 = Jean-Gabriel | last5 = Le Milbeau | first5 = Claude | last6 = Miras | first6 = Yannick | last7 = Andrieu-Ponel | first7 = Valérie | title = Sedimentary cannabinol tracks the history of hemp retting | journal = Geology | year = 2013 | volume = 41 | issue = 7 | pages = 751–754 | doi = 10.1130/G34073.1 | bibcode = 2013Geo....41..751L | url = https://insu.hal.science/insu-00781644 }}</ref><ref name="bamboo">{{cite journal | last1 = Khan | first1 = Abir | last2 = Sapuan | first2 = S. M. | last3 = Yusuf | first3 = J. | last4 = Siddiqui | first4 = Vasi Uddin | last5 = Zainudin | first5 = E. S. | last6 = Zuhri | first6 = M. Y. M. | last7 = Hang Tuah Baharuddin | first7 = B. T. | last8 = Ansari | first8 = Mubashshir Ahmad | last9 = Rahman | first9 = A. Azim A. | title = An examination of cutting-edge developments in Bamboo-PLA composite research: A comprehensive review | journal = Renewable and Sustainable Energy Reviews | volume = 188 | article-number = 113832 | publisher = Elsevier | date = 5 October 2023 | doi = 10.1016/j.rser.2023.113832 | bibcode = 2023RSERv.18813832K | url = https://doi.org/10.1016/j.rser.2023.113832| url-access = subscription }}</ref><ref name="jute">{{cite journal | last1 = Mushtaq | first1 = Bushra | last2 = Ahmad | first2 = Faheem | last3 = Nawab | first3 = Yasir | last4 = Ahmad | first4 = Sheraz | title = Optimization of the novel jute retting process to enhance the fiber quality for textile applications | journal = Heliyon | volume = 9 | issue = 11 | year = 2023 | article-number= 21513 | doi = 10.1016/j.heliyon.2023.e21513 | publisher = Elsevier | pmid = 37964854 | pmc = 10641231 | bibcode = 2023Heliy...921513M | doi-access = free }}</ref>

==Water retting== The two main methods of microbial retting are water retting and dew (field) retting.<ref name="linen"></ref> In water retting, plant stems (e.g., flax) are harvested and submerged in natural bodies of water.<ref name="linen"></ref> While underwater, anaerobic bacteria degrade the cementing compounds, typically pectin, allowing the bast fibres to separate from the woody tissues, called shive, in the stem.<ref name="linen"></ref> The stems are then removed from the water and dried by the sun before being cleaned to remove the shive.<ref name="linen"></ref> As the bacterial process was somewhat understood at the time of water retting's greatest popularity, practitioners were able to develop improvements to the process, including controlling the temperature of the water by submerging the stalks in contained tanks or pits, selecting for better microbial variety, and aerating the containers to reduce the smell and pollution generated by the bacterial action.<ref name="linen"></ref>

Water retted fibers are high quality, though the process produces more pollution than dew retting, has higher production costs, and the smell from anaerobic digestion lingers in the fibers.<ref name="linen"></ref><ref name="danish"></ref> It is also possible to over- and under-rett: over-retting results from cellulase weakening the cellulose bast fibers; under-retting results in poor separation of the fibers and shive, requiring more labor to remove the shive.<ref name="linen"></ref><ref name="danish">{{cite journal | last1 = Andresen | first1 = Stina Troldtoft | last2 = Karg | first2 = Sabine | title = Retting pits for textile fibre plants at Danish prehistoric sites dated between 800 B.C. and A.D. 1050 | journal = Vegetation History and Archaeobotany | volume = 20 | issue = 6 | year = 2011 | pages = 517–526 | publisher = Springer | doi = 10.1007/s00334-011-0324-0 | url = https://www.jstor.org/stable/23885223 | jstor = 23885223 | bibcode = 2011VegHA..20..517A }}</ref>

==Dew retting== [[File:Flax field Fecamp 01.JPG|thumb|Dew retting of flax in Normandy (2009)]] Dew retting has largely replaced water retting due to its lower production costs, higher fiber yields, and the absence of odor from the anaerobic process; however, it produces a lower and inconsistent quality fiber than water retting and takes longer (2-5 weeks compared to days for water retting).<ref name="linen"></ref><ref name="danish"></ref>

In dew retting, plant stalks are harvested and then laid out in rows to be colonized by fungi.<ref name="linen"></ref> This process requires an appropriate moisture level and temperature conducive to bacterial colonization; areas that were previously known for linen production by water retting, like England, Ireland, and Scandinavia, have declined with the increase in dew retting, as the climate is not favorable to the process.<ref name="linen"></ref> Dew retting monopolizes large tracts of land while the stems are retting.<ref name="linen"></ref> The fibers are also typically dirtied with soil and fungi from lying on the ground.<ref name="linen"></ref> Since the process is less controlled than water retting, dew retting is impacted by climate extremes, which affect fungal growth.<ref name="linen"></ref> Dew retting is common in areas with limited water resources.<ref>{{cite book |title=Industrial Applications of Natural Fibres: Structure, Properties and Technical Applications |editor1-last=Müssig |editor1-first=Jörg |publisher=John Wiley & Sons, Ltd. |year=2010 |isbn=978-0-470-66032-4 |page=96 |url=https://books.google.com/books?id=rX8S2PE71HkC&pg=PA96}}</ref>

==References== {{Reflist}}

==External links== {{Commons category}} *[https://www.youtube.com/watch?v=1pWt3PYUrQQ Video footage of the Low House retting pond]

Category:Textile arts Category:Hemp