Hemp

Uses

Hemp is used for a wide variety of purposes including the manufacture of cordage of varying tensile strength, durable clothing and nutritional products. The bast fibers can be used in 100% hemp products, but are commonly blended with other organic fibers such as flax, cotton or silk, for apparel and furnishings, most commonly at a 55%/45% hemp/cotton blend. The inner two fibers of hemp are more woody and are more often used in non-woven items and other industrial applications, such as mulch, animal bedding and litter. The oil from the fruits (“seeds”) oxidizes (commonly, though inaccurately, called “drying”) to become solid on exposure to air, similar to linseed oil, and is sometimes used in the manufacture of oil-based paints, in creams as a moisturizing agent, for cooking, and in plastics. Hemp seeds have been used in bird seed mix as well.^[4] A survey in 2003 showed that more than 95% of hemp seed sold in the EU was used in animal and bird feed.^[5] Hempseed is also used as a fishing bait.^[6]

Food

Hemp seeds can be eaten raw, ground into a meal, sprouted, made into hemp milk (akin to soy milk), prepared as tea,^[7] and used in baking. The fresh leaves can also be consumed in salads. Products include cereals, frozen waffles, hemp milk ice cream, hemp tofu, and nut butters. A few companies produce value added hemp seed items that include the seed oils, whole hemp grain (which is sterilized by law in the United States, where they import it from China and Canada), dehulled hemp seed (the whole seed without the mineral rich outer shell), hemp flour, hemp cake (a by-product of pressing the seed for oil) and hemp protein powder. ^[8]

Market share

Within the UK, the Department for Environment, Food and Rural Affairs (Defra) has treated hemp as purely a non-food crop. Seed appears on the UK market as a legal food product, and cultivation licenses are available for this purpose. In North America, hemp seed food products are sold, typically in health food stores or through mail order. The United States Department of Agriculture estimates that “the market potential for hemp seed as a food ingredient is unknown. However, it probably will remain a small market, like those for sesame and poppy seeds.”^[9] Since 2007 the commercial success of hemp food products has grown considerably.^[10][11]

Nutrition

Approximately 44% of the weight of hempseed is edible oils, containing about 80% essential fatty acids (EFAs); e.g., linoleic acid, omega-6 (LA, 55%), alpha-linolenic acid, omega-3 (ALA, 22%), in addition to gamma-linolenic acid, omega-6 (GLA, 1–4%) and stearidonic acid, omega-3 (SDA, 0–2%). Proteins (including edestin) are the other major component (33%). Hempseed’s amino acid profile is close to “complete” when compared to more common sources of proteins such as meat, milk, eggs and soy.[13] Hemp protein contains all 21 known amino acids, including the 9 essential ones[14] adult bodies cannot produce. Proteins are considered complete when they contain all the essential amino acids in sufficient quantities and ratios to meet the body’s needs. The proportions of linoleic acid and alpha-linolenic acid in one tablespoon (15 ml) per day of hemp oil easily provides human daily requirements for EFAs.

Fiber

Hemp fiber was widely used throughout history. Items ranging from rope, to fabrics, to industrial materials were made from hemp fiber. Hemp was often used to make sail canvas, and the word canvas derives from cannabis.^[15][16] Today, a modest hemp fabric industry exists, and hemp fibers can be used in clothing.^[17] Pure hemp has a texture similar to linen.^[18]

Building material

Concrete-like blocks made with hemp and lime have been used as an insulating material for construction. Such blocks are not strong enough to be used for structural elements; they must be supported by a brick, wood, or steel frame.^[19] However hemp fibres are extremely strong and durable and have been shown to be used in replacement of wood for many jobs including creating very durable and breathable homes.

The first example of the use of hempcrete was in 1986 in France with the renovation of the Maison de la Turque in Nogent-sur-Seine by the innovator Charles Rasetti.^[20] In the UK hemp lime was first used in 2000 for the construction of two test dwellings in Haverhill.^[21] Designed by Modece Architects,^[22] who pioneered hemp’s use in UK construction, the hemp houses were monitored in comparison with other standard dwellings by BRE. Completed in 2009, The Renewable House is one of the most technologically advanced made from hemp-based materials.^[23] The first US home made of hemp-based materials was completed in August 2010 in Asheville, North Carolina.^[24]

In 2013, a completely new approach to hemp in construction has been developed by Hemp Architecture,^[25] who are researching the potential use of the whole hemp stalk.
In modern times hemp is used for industrial purposes including paper, textiles, clothing, biodegradable plastics, construction (as with Hempcrete and insulation), body products, health food and bio-fuel.
Hempcrete is a mixture of hemp hurds (shives) and lime (possibly including natural hydraulic lime,[1] sand, pozzolans or cement) used as a material for construction and insulation.[2] It is marketed names like Hemcrete, Canobiote, Canosmose, and Isochanvre.[3] Hempcrete is easier to work with than traditional lime mixes and acts as an insulator and moisture regulator. It lacks the brittleness of concrete and consequently does not need expansion joints.[3]
However, the typical compressive strength is around 1 MPa,[4] around 1/20 that of residential grade concrete. Hempcrete walls must be used together with a frame of another material that supports the vertical load in building construction. Hempcrete’s density is 15% of traditional concrete, as well as carbon negative.[5] Like other plant products, the hemp crop absorbs CO2 gas as it grows, retaining the carbon and releasing the oxygen. 165 kg of carbon can be theoretically absorbed and locked up by 1 m3 of hempcrete wall over many decades.[6]

Plastic and composite materials

A mixture of fibreglass, hemp fiber, kenaf, and flax has been used since 2002 to make composite panels for automobiles.^[10][26] The choice of which bast fiber to use is primarily based on cost and availability. Various car makers are beginning to use hemp in their cars, including Audi, BMW, Ford, GM, Chrysler, Honda, Iveco, Lotus, Mercedes, Mitsubishi, Porsche, Saturn, Volkswagen^[27] and Volvo. For example, the Lotus Eco Elise ^[28] and the Mercedes C-Class both contain hemp (up to 20 kg in each car in the case of the latter).^[29]

Paper

History and development

The first identified coarse paper, made from hemp, dates to the early Western Han Dynasty, two hundred years before the nominal invention of papermaking by Cai Lun, who improved and standardized paper production using a range of inexpensive materials, including hemp ends, approximately 2000 years ago.^[30] Recycled hemp clothing, rags and fishing nets were used as inputs for paper production.

The Saint Petersburg, Russia paper mill of Goznak opened in 1818. It used hemp as its main input material. Paper from the mill was used in the printing of “bank notes, stamped paper, credit bills, postal stamps, bonds, stocks, and other watermarked paper.”^[31]

In 1916, U.S. Department of Agriculture chief scientists Lyster Hoxie Dewey and Jason L. Merrill created paper made from hemp pulp and concluded that paper from hemp hurds was “favorable in comparison with those used with pulp wood.”^[32][33] Modern research has not confirmed the positive finding about hemp hurds. They are only 32% and 38% cellulose.^[34] The actual production of hemp fiber in the U.S continued to decline until 1933 to around 500 tons/year. Between 1934-35, the cultivation of hemp began to increase but still at a very low level and with no significant increase of paper from hemp.^[35][36]

Contemporary

Hemp has never been used for commercial high-volume paper production due to its relatively high processing cost.^[37] Currently there is a small niche market for hemp pulp, for example as cigarette paper.^[38] Hemp fiber is mixed with fiber from other sources than hemp. In 1994 there was no significant production of 100% true hemp paper.^[39] World hemp pulp production was believed to be around 120,000 tons per year in 1991 which was about 0.05% of the world’s annual pulp production volume.^[40] The total world production of hemp fiber had in 2003 declined to about 60 000 from 80 000 tons.^[38] This can be compared to a typical pulp mill for wood fiber, which is never smaller than 250,000 tons per annum.^[39][41] The cost of hemp pulp is approximately six times that of wood pulp,^[40] mostly because of the small size and outdated equipment of the few hemp processing plants in the Western world, and because hemp is harvested once a year (during August)^{[citation needed]} and needs to be stored to feed the mill the whole year through. This storage requires a lot of (mostly manual) handling of the bulky stalk bundles. Another issue is that the entire hemp plant cannot be economically prepared for paper production. While the wood products industry uses nearly 100% of the fiber from harvested trees, only about 25% of the dried hemp stem — the bark, called bast — contains the long, strong fibers desirable for paper production.^[42] All this accounts for a high raw material cost. Hemp pulp is bleached with hydrogen peroxide, a process today also commonly used for wood pulp.

Market share

Around the year 2000, the production quantity of flax and hemp pulp total 25000-30000 tons per year, having been produced from approximately 37000-45000 tonnes fibers. Up to 80% of the produced pulp is used for specialty papers (including 95% of cigarette paper). Only about 20% hemp fiber input goes into the standard pulp area and are here mostly in lower quality (untreated oakum high shive content added) wood pulps. With hemp pulp alone, the proportion of specialty papers probably at about 99%. The market is considered saturated with little or no growth in this area.^[43][44]

Jewelry

Hemp jewelry is the product of knotting hemp twine through the practice of macramé. Hemp jewelry includes bracelets, necklaces, anklets, rings, watches and other adornments. Some jewelry features beads made from glass, stone, wood and bones. The hemp twine varies in thickness and comes in a variety of colors. There are many different stitches used to create hemp jewelry, however, the half knot and full knot stitches are most common.

Cordage

Hemp rope was used in the age of sailing ships, though the rope had to be protected by tarring, since hemp rope has a propensity for breaking from rot, as the capillary effect of the rope-woven fibers tended to hold liquid at the interior, while seeming dry from the outside.^[45] Tarring was a labor-intensive process, and earned sailors the nickname “Jack Tar“. Hemp rope was phased out when Manila, which does not require tarring, became widely available. Manila is sometimes referred to as Manila hemp, but is not related to hemp; it is abacá, a species of banana.

Animal bedding

Hemp shives are the core of the stem, hemp hurds are broken parts of the core. In the EU, they are used for animal bedding (horses, for instance), or for horticultural mulch.^[46] Industrial hemp is much more profitable if both fibers and shives (or even seeds) can be used.

Water and soil purification

Hemp can be used as a “mop crop” to clear impurities out of wastewater, such as sewage effluent, excessive phosphorus from chicken litter, or other unwanted substances or chemicals. Eco-technologist Dr. Keith Bolton from Southern Cross University in Lismore, New South Wales, Australia, is a leading researcher in this area. Hemp is being used to clean contaminants at the Chernobyl nuclear disaster site. This is known as phytoremediation – the process by the cleaning radiation as well as a variety of other toxins from the soil, water, and air.^[47]

Weed control

Hemp, because of its height, dense foliage and its high planting density as a crop, is a very effective and long used method of killing tough weeds in farming by minimizing the pool of weed seeds of the soil.^[48] Using hemp this way can help farmers avoid the use of herbicides, to help gain organic certification and to gain the benefits of crop rotation per se. Due to its rapid, dense growth characteristics, in some jurisdictions hemp is considered a prohibited noxious weed, much like Scotch Broom. It has been used extensively to kill weeds in agriculture.

Fuel

Biofuels, such as biodiesel and alcohol fuel, can be made from the oils in hemp seeds and stalks, and the fermentation of the plant as a whole, respectively. Biodiesel produced from hemp is sometimes known as “hempoline”.^[49]

Filtered hemp oil can be used directly to power diesel engines. In 1892, Rudolf Diesel invented the diesel engine, which he intended to fuel “by a variety of fuels, especially vegetable and seed oils, which earlier were used for oil lamps, i.e. the Argand lamp.”^[50][51][52]

Production of vehicle fuel from hemp is very small. Commercial biodiesel and biogas is typically produced from cereals, coconuts, palmseeds and cheaper raw materials like garbage, wastewater, dead plant and animal material, animal feces and kitchen waste.^[53]

Cultivation

Hemp is usually planted between March and May in the northern hemisphere, between September and November in the southern hemisphere.^[54] It matures in about three to four months.

Millennia of selective breeding have resulted in varieties that look quite different. Also, breeding since circa 1930 has focused quite specifically on producing strains which would perform very poorly as sources of drug material. Hemp grown for fiber is planted closely, resulting in tall, slender plants with long fibers.^[55] Ideally, according to Britain’s Department for Environment, Food and Rural Affairs, the herb should be harvested before it flowers. This early cropping is done because fiber quality declines if flowering is allowed and, incidentally, this cropping also pre-empts the herb’s maturity as a potential source of drug material.^{[citation needed]} However, in these strains of industrial hemp the tetrahydrocannabinol (THC) content would have been very low, regardless.

The seeds are sown from mid April to mid May with grain drills to 4–6 cm sowing depth. Hemp needs less fertilizer than corn does. A total of 60–150 kg of nitrogen, 40–140 kg phosphorus (P₂O₅) and 75–200 kg of potassium [5] per acre for hemp fiber made before sowing and again later, maybe three to four weeks. When practiced, especially in France double use of fiber and seed fertilization with nitrogen doses up to 100 kg / ha rather low. Organic fertilizers such as manure can utilize industrial hemp well. Neither weeds nor crop protection measures are necessary.^{[citation needed]}

Cultivars

A total of 41 varieties of hemp with low levels of tetrahydrocannabinol (THC) are certified by the European Union (EU).^[56] They have, unlike other types, a very high fiber content of 30-40%. In contrast to cannabis for medical use, varieties grown for fiber and seed have less than 0.2% THC and they are unsuitable for producing hashish and marijuana.^[57] The most important cannabinoid in industrial hemp is cannabidiol (CBD) with a proportion of 1 to 5%.

The variety of appearances for cannabis. Only C. sativa (left) is suited for industrial hemp, but it also has medicinal varieties.

Cannabis sativa L. subsp. sativa var. sativa is the variety grown for industrial use, while C. sativa subsp. indica generally has poor fiber quality and is primarily used for recreational and medicinal purposes. The major difference between the two types of plants is the appearance and the amount of Δ⁹-tetrahydrocannabinol (THC) secreted in a resinous mixture by epidermal hairs called glandular trichomes, although they can also be distinguished genetically.^[58] Oilseed and fiber varieties of Cannabis approved for industrial hemp production produce only minute amounts of this psychoactive drug, not enough for any physical or psychological effects. Typically, hemp contains below 0.3% THC, while cultivars of Cannabis grown for recreational use can contain anywhere from 2% to over 20%.^[59]

Harvesting

The cut hemp is laid in swathes to dry for up to four days. This was traditionally followed by retting, either water retting (the bundled hemp floats in water) or dew retting (the hemp remains on the ground and is affected by the moisture in dew, and by molds and bacterial action). Modern processes use steam and machinery to separate the fiber, a process known as thermomechanical pulping.

Environmental impact

Hemp is considered by a 1998 study in Environmental Economics to be environmentally friendly due to a decrease of land use and other environmental impacts, indicating a possible decrease of ecological footprint in a US context compared to typical benchmarks.^[60] A 2010 study, however, that compared the production of paper specifically from hemp and eucalyptus concluded that “industrial hemp presents higher environmental impacts than eucalyptus paper”; however, the article also highlights that “there is scope for improving industrial hemp paper production”.^[61] Hemp is also claimed to require few pesticides and no herbicides, and it has been called a carbon negative raw material.^[62][63] Results indicate that high yield of hemp may require high total nutrient levels (field plus fertilizer nutrients) similar to a high yielding wheat crop.^[64]

Producers

The world-leading producer of hemp is China, with smaller production in Europe, Chile and North Korea. Over thirty countries produce industrial hemp, including Australia, Austria, Canada, Chile, China, Denmark, Egypt, Finland, France, Germany, Great Britain, Hungary, India, Italy, Japan, Korea, Netherlands, New Zealand, Poland, Portugal, Romania, Russia, Slovenia, Spain, Sweden, Switzerland, Thailand, Turkey and Ukraine.^[65][66]

The United Kingdom, and Germany all resumed commercial production in the 1990s. British production is mostly used as bedding for horses; other uses are under development. Companies in Canada, the UK, the United States and Germany, among many others, process hemp seed into a growing range of food products and cosmetics; many traditional growing countries still continue to produce textile-grade fibre.

FAO argue that an optimum yield of hemp fiber is more than 2 tonnes per ha, while average yields are around 650 kg/ha.^[69]

The post Hemp appeared first on The View from the Grassy Knoll.