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Coir
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What is coir?
Coir is a coarse fibre obtained from the tissues surrounding the seed of the coconut palm, Cocos nucifera. The intact fruit has a smooth leathery skin above the thick fibrous layer. This surrounds the stony dark brown shell, which is actually part of the fruit rather than the seed. Inside the shell are the papery brown outer layer of the seed surrounding the nutritious white flesh and the embryo.
The fibrous layer forms a strong, shock-absorbing mesh which protects the seed from mechanical damage and is water-resistant. The individual fibre cells are narrow and hollow, with thick walls made of cellulose. They are pale when immature but later they become hardened and yellowed when a layer of lignin, a complex woody chemical, is deposited on their walls. Mature brown coir fibres contain more lignin and less cellulose than fibres such as flax and cotton and so are stronger but less flexible. White fibre is smoother and finer than the harder brown fibre but is also weaker. The coir fibre is relatively water-proof and is the only natural fibre resistant to damage by salt water.
What does the coconut palm look like?
The coconut palm has a smooth, light grey, unbranched trunk (up to 25 m in height), rising from a swollen base, topped by a crown of long, feather-like leaves. Coconut palms produce inflorescences in the leaf axils (the angle between the base of the leaf-stalk and the trunk) which bear both male and female flowers. The fruits, which grow from fertilised female flowers, take a year to develop.
Where is the coconut palm grown?
They are grown throughout the Indo-Malaysian region, on the Ivory Coast, Dahomey and Togo, West Africa and in Mozambique, Kenya, Tanzania and Central and South America. Coconut palms are among the most useful plants grown by people, providing valuable commodities in the form of copra (dried coconut flesh) and oil, as well as building material, thatch, food, drink and ornament.
Total world coir fibre production is 250,000 tonnes. The coir fibre industry is particularly important in some areas of the developing world. India, mainly the coastal region of Kerala State, produces 60% of the total world supply of white coir fibre. Sri Lanka produces 36% of the total world brown fibre output. Over 50% of the coir fibre produced annually throughout the world is consumed in the countries of origin, mainly India.
How is the coconut palm grown?
Coconut palms require conditions of high humidity and plenty of sunlight. They will grow on a wide variety of well-drained soils but a constant supply of fresh water is essential. These conditions are often available on sea shores.
Harvesting fruits from tall palms can be so difficult that in some coconut-growing areas in Indonesia and Thailand the pig-tailed macaque monkey (Pithecus memestrinus) has been trained to climb the trees to collect the nuts. The monkeys are well-treated and prized for their skill. Coconuts are harvested every two months throughout the year.
How is coir processed?
Green coconuts, harvested after about twelve months on the plant, contain pliable white fibres. Brown fibre is obtained by harvesting fully mature coconuts when the nutritious layer surrounding the seed is ready to be processed into copra and desiccated coconut. The fibrous layer of the fruit is separated from the hard shell by driving the fruit down onto a spike to split it (de-husking).
Brown fibre processing
The fibrous husks are soaked in pits or in nets in a slow moving body of water to swell and soften the fibres. The long bristle fibres are separated from the shorter mattress fibres underneath the skin of the nut, a process known as 'wet-milling'.
The mattress fibres are sifted to remove dirt and other rubbish, dried and packed into bales. Some mattress fibre is allowed to retain more moisture so that it retains its elasticity for 'twisted' fibre production. The coir fibre is elastic enough to twist without breaking and it holds a curl as though permanently waved. Twisting is done by simply making a rope of the hank of fibre and twisting it using a machine or by hand.
The longer bristle fibre is washed in clean water and then dried before being tied into bundles or hunks. Although bristle fibre may be sold without further processing, it may be cleaned and 'hackled' by steel combs to straighten the fibres and remove any shorter fibre pieces. Coir bristle fibre may also be bleached and dyed to provide buyers with hanks of different colours.
White fibre processing
To separate the white fibres, the immature husks are suspended in a river or water-filled pit for up to ten months. During this time micro-organisms break down the plant tissues surrounding the fibres to loosen them - a process known as retting. Segments of the husk are then beaten by hand to separate out the long fibres which are subsequently dried and cleaned. Cleaned fibre is ready for spinning into yarn in the home using a simple one-handed system or a spinning wheel. The final operation is grading before sale and shipping.
How is coir used?
Brown coir is used in brushes, doormats, mattresses and sacking. A small amount is also made into twine, used in this country as hop strings. Pads of curled brown coir fibre, made by 'needle-felting' (a machine technique that mats the fibres together) are shaped and cut to fill mattresses and for use in erosion control on river banks and hillsides. A major proportion of brown coir pads are sprayed with rubber latex which bonds the fibres together to be used as upholstery padding for the automobile industry in Europe. The material is also used for insulation and packaging.
The major use of white coir is in rope manufacture. Mats of woven coir fibre are made from the finer grades of bristle and white fibre using hand or mechanical looms.
History
The coconut palm may have originated in the lands around the western Pacific; from there it was probably distributed east- and west-wards by early peoples. It was also dispersed by ocean currents, with the seeds protected by the fibrous fruit. Germinating coconuts were found washed up on the shores of the newly-born volcanic island, Anak Krakatoa, in the 1930s.
Coconut palms have been known and used in India for 3,000 years. A letter written by an Arab trader of the eleventh century noted that the fibre from the palm was resistant to sea water. The Arab traders also taught the population of the Sinhalese and Malabar coast how to prepare the fibre from the nut, since by this time the palm was widespread along the Indo-Malaysian coast. When Marco Polo visited China in the fourteenth century, he was told that coir fibre from the 'Indian Nut' had been used by the Chinese for 500 years. In the mid-sixteenth century the palm was introduced into Spain and Portugal, Brazil and Puerto Rico by sea-faring traders. The name 'coconut' may have been coined by Spanish sailors to describe the monkey-faced appearance of the coconut.
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