Too coarse for clothing and upholstery, sisal is replacing glass fibres in composite materials used to make cars and furniture
Sisal fibre is obtained from Agave sisalana, a native of Mexico. The hardy plant grows well in a variety of hot climates, including dry areas unsuitable for other crops. After harvest, its leaves are cut and crushed in order to separate the pulp from the fibres. The average yield of dried fibres is about 1 tonnes per hectare, although yields in East Africa reach 2.5 tonnes.
Lustrous and creamy white, sisal fibre measures up to 1 m in length, with a diameter of 200 to 400 microns. It is a coarse, hard fibre unsuitable for textiles or fabrics. But it is strong, durable and stretchable, does not absorb moisture easily, resists saltwater deterioration, and has a fine surface texture that accepts a wide range of dyes.
CNR-ISMAC, Biella, Italy
Sisal is cultivated for fibre in Brazil, China, Cuba, Kenya, Haiti, Madagascar, and Mexico. Production patterns differ between counties. In Tanzania and Kenya sisal is predominantly a plantation crop, while production in Brazil is largely small-scale.
Production and trade
World production of sisal and a similar agave fibre, henequen, is estimated at around 300 000 tonnes, valued at $75 million. The major producers are Brazil (120 000 tonnes), Tanzania (30 000) and Kenya (25 000). Brazil exports around 100 000 tonnes of raw fibre and manufactured goods, particularly rope to the USA. Kenya exports around 20 000 tonnes and Tanzania 15 000 tonnes.
Uses of sisal
Sisal is used in twine and ropes, but competition from polypropylene has weakened demand.
But other markets are emerging - today, sisal can be found in speciality paper, filters, geotextiles, mattresses, carpets and wall coverings.
It is used as reinforcement in plastic composite materials, particularly in automotive components, but also in furniture. Another promising use is as a substitute for asbestos in brake pads. (It is also the best material for making dartboards.)
By-products from sisal extraction can be used for making bio-gas, pharmaceutical ingredients and building material.