Easy to grow without agrochemicals, hemp is used increasingly in agrotextiles, car panels and fibreboard, and "cottonized" for clothing
Hemp fibre is obtained from the bast of the plant Cannabis sativa L. It grows easily - to a height of 4 m - without agrochemicals and captures large quantities of carbon. Production of hemp is restricted in some countries, where the plant is confused with marijuana. Optimum yield of hemp fibre is more than 2 tonnes per ha, while average yields are around 650 kg.
Long, strong and durable, hemp fibres are about 70% cellulose and contain low levels of lignin (around 8-10%). The fibre diameter ranges from 16 to 50 microns. Hemp 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.
CNR-ISMAC, Biella, Italy
The world's leading producer of hemp is China (above), with smaller production in Europe, Chile and the Democratic People's Republic of Korea. In the European Union hemp is grown on around 15 000 ha of land. Major producers are France, Germany and the UK.
Production and trade
Between 2000 and 2006, world production of hemp fibre grew from 50 000 tonnes to almost 90 000 tonnes, almost half of it produced in China. Production in the EU was 23 000 tonnes. China is the largest exporter of hemp textiles, mainly to Europe and North America, where the market for hemp clothing is growing rapidly. China also exports hemp-based fibreboard.
Uses of hemp
Hemp has been used for centuries to make rope, canvas and paper. Long hemp fibres can be spun and woven to make crisp, linen-like fabric used in clothing, home furnishing textiles and floor coverings.
In China, hemp is de-gummed for processing on flax or cotton machinery. Blending with cotton, linen, silk and wool gives hemp a softer feel, while adding resistance and durability to the product.
In Europe, hemp fibres are used mainly in the special paper industry - thanks to lower lignin content, it can be pulped using fewer chemicals than wood.
Hemp fibres are also used to reinforce moulded thermoplastics in the automobile industry. The short core fibres go into insulation products, fibreboard and erosion control mats, while the fibrous core can be blended with lime to make strong, lightweight concrete.