February 4 is National Hemp Day. Since there exist many misconceptions regarding hemp, in general, this post’s aim is to increase the awareness and knowledge of hemp as a fiber for textiles. Recently, the textile industry re-introduced hemp and flax to decrease the environmental impacts of fashion. Read to be informed about hemp and its thermal and physiological properties for thermal comfort in fashion.
- History of Hemp Use
- Growing Conditions for Hemp
- Material Properties of Hemp as a Fiber for Textiles
- Moisture management of woven and knitted hemp fabrics
- The Use of Hemp in Denim
- Chemical Treatment of Hemp Fibers for Improved Moisture Management
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History of Hemp Use
According to archeological data, hemp (Cannabis sativa L.) was cultivated since 5000 to 6000 years. The Er Ya, the earliest Chinese dictionary, written about 2200 years ago, shows that the Chinese recognized the sex of the plants: “Male hemp is called xi ma, female hemp is called ju ma.” It also documents the use of the thin, soft male hemp for clothing.
Archaeological finds of hemp pollen and seeds provide evidence for hemp cultivation in northern Scandinavia between 350 BC and 450 AD. However, these finds fail to prove textile use of flax and hemp because the seeds can also provide oil and food. In Japan, wearing hemp kimonos dates back to at least 300 AD. A tapestry in a Norwegian ship dated as 800 AD showed besides wool remains of hemp and flax. Examinations of textile finds from the Middle Ages suggest that the Vikings used hemp and flax not only for ropes and sail cloths, but also in blended and fine household textiles.
Historically, the word linen was used for any plant-based woven fabric . At the end of the 18th Century, hemp las a fiber for textiles lost its importance because American laws favored the growth and trade of cotton. About 100 years ago, big companies pushed for the use of synthetics. Nowadays, the word linen refers to cloth from cotton.
Growing Conditions for Hemp
Hemp grows well on soils suitable for crops. However, hemp also grows on muddy soils and soils with high pH and muddy soils like they are common in Scandinavia, Siberia, and Alaska. In these regions, mountains, coniferous forest, swamps, marshes, and around lakes prevail. Today a lot of hemp is grown in Alaska.
Material Properties of Hemp as a Fiber for Textiles
Hemp has several advantages over other fabrics. It is the most durable and strongest of all natural textile fibers. It becomes softer with each time in the laundry without fiber degradation. Hemp is resistant to mildew, mold, rot, and UV radiation. It has a high absorptivity, for which it takes up dye easily. Regarding the wearing comfort, hemp is breathable and anti-microbial. Because of its biodegradability, the fashion industry labels hemp as eco-friendly.
From an aesthetic point of view the main disadvantages of hemp are that it wrinkles easily and doesn’t drape nicely. Hemp fabrics can feel harsh.
Moisture Management of Woven and Knitted Hemp Fabrics
Moisture management of fabrics is important for thermal and physiological comfort of the wearer. The term moisture management refers to the controlled movement of water vapor and liquid water (aka sweat from perspiration) from the skin to the ambient air thru the fabric. It depends among other things on the yarn twist, weave, or knit density. The latter two are often expressed as yarn count. In general, the overall moisture management capacity of woven hemp fabrics increases as the yarn number increase. As a result, hemp fabric is a great clothing material for hot climates.
The Use of Hemp in Denim
Recently, the textile industry started using flax/hemp blends for denim fabrics instead of cotton, for instance Levi’s. According to research, the moisture comfort properties and thermal resistance of blended denim is better than that of cotton denim. Production washing treatments like rinse, stone, or bleach washes improve the comfort properties of all the denim fabrics in nearly the same way.
Using cotton/flax and cotton/hemp blended fabrics with 2/1 twill and 3/1 twill weaves improves the thermo-physiological comfort and softness of denim fabrics. The blended denim has higher air permeability and water absorbency along with quick-drying behavior as compared to pure cotton denim.
Chemical Treatment of Hemp Fibers for Improved Moisture Management
In the textile industry, chemical treatment of fibers or yarns is common to change the appearance, or to improve the thermal and/or physiological comfort. The so-called liquid ammonium treatment, for instance, changes the crystal structure of hemp fiber from cellulose I into a mix of cellulose III and cellulose I. This treatment decreases the crystallinity from 66.1% to 57.4%. As a result, L/A-treated hemp woven fabrics show improved liquid moisture management properties as compared to untreated ones.
Hemp as a Fiber for Textiles in a Nutshell
Clothing made from hemp or hemp blended fabrics are naturally moisture wicking, and antimicrobial, which means less stank. They also offer great breathability. Fabric from 100% hemp with or without L/A treatment is bio-degradable. Because hemp is sustainable and considered environmentally friendly, various high end brands, for instance, Max Mara, Jil Sander, have hemp items in their collections. Both high-end stores like net-a-porter, Nordstrom, and low end stores like Walmart recently offer hemp or hemp blended clothing as part of the sustainability and eco-friendly fashion trend.
Get your first hemp garment.
Lu, X., and Clarke, R.C.. The cultivation and use of hemp in ancient China
Okur, N., 2021. Thermo-physiological and Handle-related Comfort Properties of Hemp and Flax Blended Denim Fabrics, Journal of Natural Fibers, doi: 10.1080/15440478.2021.1993488
Saricam C., 2021. The comfort properties of hemp and flax blended denim fabrics with common industrial washing treatments. Textile Research Journal. doi:10.1177/00405175211054216
Skoglund, G., Nockert, M. & Holst, B., 2013. Viking and Early Middle Ages Northern Scandinavian Textiles Proven to be made with Hemp. Sci Rep 3, 2686, https://doi.org/10.1038/srep02686
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