Hemp

Hemp fibre is obtained from the bast of the plant Cannabis sativaL. It grows easily – to a height of 4 m – without agrochemicals and captures large quanties of carbon. Optimum yield of hemp fibre is more than 2 tonnes per ha, while average yields are around 650 kg. Hemp fibres are about 70% cellulose and contain low levels of lignin (around 8-10%). The fibre diameter ranges from 16 to 50 microns. They are long strong and durable in nature. The fibre conducts heat, dyes well, resists mildew, blocks ultraviolet light and has natural anti-bacterial properties. Shorter, woody core fibres (“tow”) contain higher levels of lignin. The world’s leading producer of hemp is China, with smaller production in Europe, Chile and the Democratic People’s Republic of Korea, France, Germany and the UK.

Hemp is used for many varieties of products 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. In modern times hemp is used for industrial purposes including paper, textiles, clothing, biodegradable plastics, construction (as with Hemp Crete and insulation), body products, health food and bio-fuel. Long hemp fibres can be spun and woven to make crisp, linen-like fabric used in clothing, home furnishing textiles and floor coverings. Hemp fibres are also used to reinforce moulded thermoplastics in the automobile industry. The short core fibres go into insulation products, fibre board and erosion control mats, while the fibrous core can be blended with lime to make strong, lightweight concrete.

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