Hemp or industrial hemp typically found in the northern hemisphere, is a variety of the Cannabis sativa plant species that is grown specifically for the industrial uses. It is one of the fastest growing plants and was one of the first plants to be spun into usable fiber 10,000 years ago. It can be refined into a variety of commercial items including paper, textiles, clothing, biodegradable plastics, paint, insulation, biofuel, food, and animal feed.
Although cannabis as a drug and industrial hemp are both members of the species Cannabis sativa and contain the psychoactive component tetrahydrocannabinol (THC), they are distinct strains with unique biochemical compositions and uses. Hemp has lower concentrations of THC and higher concentrations of cannabidiol (CBD), which decreases or eliminates its psychoactive effects. The legality of industrial hemp varies widely between countries. Some governments regulate the concentration of THC.
Hemp is used to make a variety of commercial and industrial products including rope, clothes, food, paper, textiles, plastics, insulation and biofuel. The bast fibers can be used to make textiles that are 100% hemp, but they are commonly blended with other organic fibers such as flax, cotton or silk, to make woven fabrics for apparel and furnishings. The inner two fibers of the plant are more woody and typically have industrial applications, such as mulch, animal bedding and litter. When oxidized (commonly referred to as "drying"), hemp oil from the seeds becomes solid and can be 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 feed mix as well.
Hemp seeds can be eaten raw, ground into a meal, sprouted, or made into dried sprout powder. The leaves of the hemp plant can be consumed raw in salads. Hemp can also be made into a liquid and used for baking or for beverages such as hemp milk, hemp juice, and tea. Hempseed oil is cold-pressed from the seed and is high in unsaturated fatty acids. In 2011, the U.S. imported $11.5 million worth of hemp products, mostly driven by growth in demand for hemp seed and hemp oil for use as ingredients in foods such as granola.
In the UK, the Department for Environment, Food and Rural Affairs treats hemp as a purely non-food crop, but with proper licensing and proof of less than 0.3% THC concentration, hemp seeds can be imported for sowing or for sale as a food or food ingredient. In the U.S., imported hemp can be used legally in food products and as of 2000, was typically sold in health food stores or through mail order.
Hemp fiber has been used extensively throughout history, with production climaxing soon after being introduced to the New World. 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. Today, a modest hemp fabric industry exists, and hemp fibers can be used in clothing. Pure hemp has a texture similar to linen.
Traditionally the hemp stalks would be water-retted first before the fibers were beaten off the inner hurd by hand; a process known as scrutching. As mechanical technology evolved, separating the fiber from the core was accomplished by crushing rollers and brush rollers that would produce a nearly clean fiber. After the Marijuana Tax Act was implemented in 1937, the technology for separating the fibers from the core remained "frozen in time".
Only in 1997, starting with Ireland, did the Commonwealth countries and then other countries begin to legally grow industrial hemp again. Reiterations of the 1930's "decorticator" have been met with limited success, along with steam explosion and chemical processing known as thermomechanical pulping.
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. However hemp fibres are extremely strong and durable, and have been shown to be usable as a replacement for 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. In the UK hemp lime was first used in 2000 for the construction of two test dwellings in Haverhill. Designed by Modece Architects, 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. The first US home made of hemp-based materials was completed in August 2010 in Asheville, North Carolina.
A panellized system of hemp-lime panels for use in building construction is currently under test in a European Union funded research collaboration led by the University of Bath. The panels are being designed to assure high quality construction, rapid on-site erection, optimal hygrothermal performance from day one and energy and resource efficient buildings. The 36-month-long work program aims to refine product and manufacturing protocols, produce data for certification and marketing, warranty, insurance cover and availability of finance. It also includes the development of markets in Britain, France and Spain.
Hemp is used as an internal plaster and is a mixture of hemp hurd (shive) mixed with larger proportions of a lime-based binder. Hemp plaster has insulation qualities.
A mixture of fiberglass, hemp fiber, kenaf, and flax has been used since 2002 to make composite panels for automobiles. 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 and Volvo. For example, the Lotus Eco Elise and the Mercedes C-Class both contain hemp up to 20 kg in each car.
Ancient Sanskrit on Hemp based Paper. Hemp Fiber was commonly used in the production of paper from 200
Before the industrialisation of the paper production the most common fibre source was recycled fibres from used textiles, called rags. The rags were from hemp, linen and cotton. A process for removing printing inks from recycled paper was invented by German jurist Justus Claproth in 1774. Today this method is called deinking. It was not until the introduction of wood pulp in 1843 that paper production was not dependent on recycled materials from ragpickers.
History and development
Wrapping paper with hemp fiber excavated from the Han Tomb of Wu Di (140-87 BC) at Baqiao, Xi'An.
The first identified coarse paper, made from hemp, dates to the early Western Han Dynasty, two hundred years before the nominal invention of paper making by Cai Lun, who improved and standardized paper production using a range of inexpensive materials, including hemp ends, approximately 2000 years ago. 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."
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."The chemical composition of hemp hurds is similar to that of wood, making hemp a good choice as a raw material for manufacturing paper. Modern research has not confirmed the positive finding about hemp hurds from 1916. A later book about hemp and other fibers by the same L.H. Dewey(1943) have no words about hemp as a raw material for production of paper. Dried hemp has about 57% cellulose (the principal ingredient in paper), compared to about 40-50% in wood. Hemp also has the advantage of a lower lignin content: hemp contains only 5-24% lignin against the 20-35% found in wood. This lignin must be removed chemically and wood requires more use of chemicals in the process. 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.
Currently there is a small niche market for hemp pulp, for example as cigarette paper. Hemp fiber is mixed with fiber from other sources than hemp. In 1994 there was no significant production of 100% true hemp paper. 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. The total world production of hemp fiber had in 2003 declined to about 60,000 from 80,000 tons. This can be compared to a typical pulp mill for wood fiber, which is never smaller than 250,000 tons per annum. The cost of hemp pulp is approximately six times that of wood pulp, 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) 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. 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.
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.
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.
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. 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.
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. 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. Additionally Hemp is being used to clean contaminants at the Chernobyl nuclear disaster site. By way of a process, which is known as phytoremediation - the process of clearing radioisotopes as well as a variety of other toxins from the soil, water, and air.
The dense growth of hemp helps kill weeds, even thistle. 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. 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. Due to its rapid, dense growth characteristics, in some jurisdictions hemp is considered a prohibited noxious weed, much like Scotch Broom.
Biodiesel can be made from the oils in hemp seeds and stalks and alcohol fuel (ethanol or, less commonly, methanol) from the fermentation of the whole plant. Biodiesel produced from hemp is sometimes known as "hempoline".
Filtered hemp oil can be used directly to power diesel engines. In 1892, Rudolf Diesel invented the diesel engine, which he intended to power "by a variety of fuels, especially vegetable and seed oils, which earlier were used for oil lamps, i.e. the Argand lamp."
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.
Hemp is usually planted between March and May in the northern hemisphere, between September and November in the southern hemisphere. 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. "Until the early 1900s industrial hemp was a valuable crop used all over the world for its strong fibers and oil seeds. Today, however, the common perception of the industrial hemp plant is generally negative and associated with the drug marijuana. This perception is the legacy of a century of powerful influences construing hemp as a dangerous drug, even though it is not a drug and it has the potential to be a profitable alternative crop. In the United States, the public's perception of hemp as marijuana has blocked hemp from becoming a useful crop and product," in spite of its vital importance prior to World War II. Ideally, according to Britain's Department for Environment, Food and Rural Affairs, the herb should be desiccated and harvested towards the end of flowering. This early cropping reduces the seed yield but improves the fiber yield and quality. In these strains of industrial hemp the tetrahydrocannabinol (THC) content would have been very low.
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  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.
A total of 26 varieties of hemp with low levels of tetrahydrocannabinol (THC) are certified by the European Union (EU). 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. The most important cannabinoid in industrial hemp is cannabidiol (CBD) with a proportion of 1 to 5%.
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 female buds from this variety are primarily used for recreational and medicinal purposes. The major differences between the two types of plants are 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. 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 medicinal or recreational use can contain anywhere from 2% to over 20%.
Smallholder plots are usually harvested by hand. The plants are cut at 2 to 3 cm above the soil and left on the ground to dry. Mechanical harvesting is now common, using specially adapted cutter-binders or simpler cutters.
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).
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. 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". Hemp is also claimed to require few pesticides and no herbicides, and it has been called a carbon negative raw material. Results indicate that high yield of hemp may require high total nutrient levels (field plus fertilizer nutrients) similar to a high yielding wheat crop.
Hemp was made illegal to grow without a permit in the U.S. under the Controlled Substances Act passed in 1970 because of its relation to marijuana, and any imported hemp products must meet a zero tolerance level. Some states have made the cultivation of industrial hemp legal, but farmers in many states have not yet begun to grow it because of resistance from the federal Drug Enforcement Administration. In 2013, after the legalization of cannabis in the state, several farmers in Colorado planted and harvested several acres of hemp, bringing in the first hemp crop in the United States in over half a century. Colorado, Vermont, California, and North Dakota have passed laws enabling hemp licensure. All four states are waiting for permission to grow hemp from the DEA. Currently, Oregon has licensed industrial hemp as of August 2009. Congress included a provision in the Agricultural Act of 2014 that allowed colleges and state agencies to grow and conduct research on hemp in states where it is legal. Hemp production in Kentucky, formerly the United States' leading producer, resumed in 2014.
As of 2015 the hemp industry estimated that annual sales of hemp products were around US$580 million annually; hemp seeds have been the major force driving this growth.
Yet, even with this progress, hemp businesses seem to face difficulty expanding in the US as they face challenges in traditional marketing and sales approaches. According to the case study done by Forbes, hemp businesses and startups, such as Ministry of Hemp, have had difficulty marketing and selling non-psychoactive hemp products, as social media and financial institutions refuse to distinguish between hemp and marijuana.