Hemp, cannabis sativa, as opposed to it’s medicinal cousin cannabis sativa indica, is a cellulosic bast fibre that was once heavily relied upon as the sturdiest of textile fibres. It may not necessarily need to be said, but hemp has become somewhat of a political plant over the years! It should also be said that hemp is different from cannabis and contains very low psychoactive agents, those of which that are deeply desired from cannabis. The use of hemp is entirely functional and given to textile, food and industrial applications, a hugely practical plant. Not to mention a beautiful plant with a strong history. Hemp can be anywhere from a few feet to 12 feet tall with mass quantities of leaves, multi pointed and the greenest of green. A hemp field: tall hemp plants sway in the zephyr, leaves rustling, the plants chattering, telling and understanding old secrets and stories, sharing magic among themselves. If you’ve ever stood silent in a corn field and been taken over, try a hemp field.
At one time, hemp was respected so much as to be used as currency, individuals could even pay their tax dues with it. Hemp seeds were given to early settlers to sow on their ‘allotted homestead’ and the new colonial U.S government mandated the growth of hemp in the early colonial era. A short film titled Hemp for Victory written by Brittain B. Robinson and produced by the U.S. Department of Agriculture in 1942 encourages farmers to grow ‘as much hemp as possible’ while explaining the vast uses of the fibre… although the USDA later denied the existence of said film. Hemp was confusing and polarizing! At once highly useful, a food source, multi purpose and serving so many needs and at the same time, cannabis was looked down upon as ‘devils weed’. Unfortunately, although hemp is a different plant with different offerings, the fibre stuff was judged right along with cannabis in the steep decline of reputation.
The cultivation and sale of hemp was regulated and taxed in the USA by the ‘Marihuana Tax Act of 1937’ although it was made then a de facto illegal crop. The act was, however, once lifted during World War Two in order to produce hemp for rope to be used by the U.S. Navy. In 1801, before Canada was Canada as we now know it, the Lieutenant Governor of Upper Canada gave hemp seeds to new-to-this-land farmers for cultivation. There was a lot of hemp being tended to in Canada in those days, indeed, by 1823 there were 7 hemp mills on the prairies in Canada. By 1938 Canada followed suit of the U.S. and prohibited production of cannabis as well as hemp under the Opium and Narcotics Act and cultivation was prohibited until 1998. Now, in 2018 the legalization of cannabis is here and will, no doubt and in time, increase the growth and processing of hemp.
A back-and-forth relationship to be sure.
Interestingly and on the other side of the globe, China has never banned the growth and use of Cannabis sativa. However, at this time there are only two provinces in the country that grow hemp, one in the south and one in the north. There are speculations however, that with the population growth of China hemp growth may increase. Much of Chinas arable land is occupied with cotton, which, if you read the article about linen, yields far less fibre per acre than hemp. So, in order for the nation to meet food needs, some of that cotton space may have to be sacrificed. A plant that can take up the slack and the decline in fibre resource and meet some clothing needs for said rising population? Hemp.
Hemp is said to have evolved in central Asia and was being cultivated for textile use in China since 2800 bc; hemp reached Turtle Island by 1600 ad. Hemp may be the oldest known cultivated fibre plant and if that is true, it’s a little wonder due to the fibres favourable characteristics.
Hemp’s textile characteristics are similar to flax and likewise, it’s applications are quite varied. As mentioned earlier, hemp can be used for textiles, food and drink as well as for industrial purposes. Peoples and livestock can eat the seeds and oil, the plant can be used medicinally (not the subject of my current researches), the fibre can be used to produce home textiles and elegant as well as heavy duty clothing, twine, paper, marine supplies such as rope, sails and canvas are highly valued. In industrial use, hemp can be utilized for medium density fibreboard and biocomposites, building blocks and ‘hempcrete’. One of the sturdiest, longest lasting and majorly useful fabrics - canvas, the word actually derives from the word cannabis. Items as varied as homes, hard shell briefcases, vehicles and furniture have been produced with hemp. Further uses for the plant are being researched at the present time and hemp has for surely proven itself as a competitive product to wood and petroleum based industrial products.
As a field crop, hemp does not necessarily require regular irrigation (it’s actually tolerant of droughts) or as previously mentioned, chemical applications. The plant also contributes to overall soil health and decreases soil erosion. Hemp can destroy resident nematodes in the soil thereby improving the land and viability of future crops. As if hemp wasn’t already a superstar, it can also be used in phytoremediation practices removing heavy metals and even radioactive elements from the earth without always transferring these materials into it’s own tissues (it has been shown to transfer copper into its seeds). There have even been trial crops planted in New South Whales, Australia in areas devastated by acid rains and sewage plants with positive results - the plants restored the pH balance of the soil.
Maybe we should all be planting hemp seedlings as well as tree seedlings…
In the interest of clarity and realism and in spite of hemps ability to grow strong and well without the application of chemicals (pesticide, fungicide and herbicide), in order to decrease the amount of chaff, dust and waste found on the processing room floor and thereby attaining a higher dollar for their crop, some hemp growers do choose to use chemicals to eliminate weeds from the field. This is the nature of commercial scale production but also, for me, the reason to seek out GOTS certified yarns and fabrics.
Beyond it’s technical applications, hemp could be a boon to old growth forests. The fibre yield per acre from a crop of hemp is moreso than the other natural fibres and according to one study - one acre can yield 121- 445 pounds of conventional cotton, 80 - 102 pounds of organic cotton, 323 - 465 pounds of flax and 485 - 809 pounds of hemp. (Sourced: UK Government funded project; U of London; 1999; Kate Fletcher; demi.org.uk) Since hemp by-products of textile manufacturing can be used for similar end products as wood and pulp and since it grows much faster than soft and hard wood trees and if hemp is chosen over wood, mature trees can then be left to reach old growth thereby increasing local biodiversity, overall forest and global health which maybe, hopefully and potentially will decrease the practice of clear cut, old growth forest harvesting.
Hemp contains less lignin than other cellulosic fibres possibly making it a little easier on machinery to process. Hemp is structurally composed of 70% cellulose, 22% hemicellulose (which provides the cellular link between cellulose and lignin) and 6% lignin (the ‘plant glue’ or strengthening material found between cellulose microfibrils).
The production of hemp textiles begins in the field where the seed is sown and the plant cultivated. Usually, when hemp is dedicated for textile use, the plants are grown in a somewhat crowded manner encouraging less branch development and tall, strong main stalks, as linen is. There is even a variety of fibre hemp bred by InnoTech, Alberta that reaches 12 feet in height! The plant is typically harvested by specialized machinery either before or during the flowering stage and then let to ret in the field; field retting hemp only takes a few weeks. After retting is through, the fibre is baled and transported to go through the decortication process. Decortication is the process whereby the outer fibrous material and the woody core, called the hurd, are separated. It is interesting to note that from 3 - 4 tonnes of good quality, dry retted hemp straw can produce about 1 tonne of bast material and 2 - 3 tonnes of hurd. Like any natural product manufactured from the land, yields are dependant on the variety of plant, growing conditions, harvest practice and processing equipment. The outer fibrous material is what we textile artists come to use in our work, the hurd is utilized in industrial and building materials. Prior to decortication, the fibre is cut and hammered before the final cleaning and separation process’. Finally, the bast fibre and hurd go out to their final manufacturing fates. Even hemp leaves can be fully utilized as feed.
Hemp sourced industrial and building materials are gaining popularity. Because hemp is so quick to grow, low maintenance and so very multi purpose it is also gaining popularity among commercial as well as small scale farms. In 2014, hemp field cultivation reached 44 000 hectares in Canada. Canadian hemp expert, Jan Slaski, predicts that this number will grow immensely in the near future ballooning the national industry into one with a $1 billion value.
Hemp has a low environmental impact and the products derived from hemp have a long life, meaning that the articles made from hemp can withstand the lifetime of its synthetic counterparts. There is also some concern about synthetic building materials and ‘off gassing’; hemp, in contrast, is non toxic and does not emit harmful gases. Due to the quick growth rate of hemp, it can be see as a ‘carbon sink’. The growth and accumulation of organic matter, or biomass, produced over the lifecycle of hemp plants photosynthesizes up to 22 tonnes of atmospheric carbon dioxide per hectare. Hemp will collect and permanently store carbon.
In terms of textile use hemp, like linen, is a worker. In fact, it may last even longer than linen! Hemp produces a light cloth with bright lustre, it is highly resistant to heat and is even UV resistant (window coverings?). The fibre length can be up to 12 feet (some say more) long making the final yarns and fabric very strong. The natural colour of hemp is blonde grey to a deep brown and the fibre won’t necessarily bleach to white - this speaks to me of the strength of the fibre! Because hemp will maintain some of it’s natural colour, it isn’t commercially dyed as often as other natural fibres. Although, in my experience, it does take natural dyes beautifully although a hard scour benefits the strike rate and uptake of pigment. It is a thirsty fibre absorbing 20% of it’s weight in water and dries quickly - comfortable to wear in the summer. Its hand is similar to linen, crisp, soft and fairly smooth.
Hemp has very poor elastic recovery, even less so than linen. Because of this, it will crease and wrinkle, which some people, myself included, see as part of the charm of these plant fibres! Hemp will biodegrade at the end of it’s functional life however it is known to be anti-bacterial and will not allow mildew to grow within it’s structure. Because of these characteristics, hemp destined for textile use is employed in everything from rugged outdoor products such as canvas, rope and sails to fine fabrics for clothing and home goods. Hemp does become softer with use and age making those wearables even more enjoyable over time. But even a decades old rope, heavily used, soaked with salty ocean water, graded against mooring and rigging will prove reliable for lifetimes.
Jan Slaski - InnoTech Alberta
The Role of Industrial Hemp in Carbon Farming; Vosper, James; GoodEarth Resources PTY Ltd (ABN 79 124 022 859)