The sisal plant has a 7-10 year life-span (longer in Mexico where growth is slower) and is usually cut first after 2-3 years and then at 6-12 month intervals. A typical plant will produce 200-250 commercially usable leaves in its life-time (hybrid varieties up to 400-450 leaves) and each leaf contains an average of around 1000 fibres.
The fibre element, which accounts for only about 4% of the plant by weight, is extracted by a process known as decortication.
In East Africa, where sisal is produced on an estate basis, the leaves are in the main transported to a central decortication plant after which the fibre is dried, brushed and baled – for export or for use in the domestic mills. In Brazil it is mainly grown by small-holders and the fibre is extracted by teams using portable raspadors.
East African sisal, being washed and decorticated, is considered to be superior in quality to Brazilian sisal (although the latter is more than adequate for the manufacture of agricultural twines and general cordage and is used domestically in craft paper production) and, in normal times, commands a significant price premium on the world market.
Sisal is the coarsest vegetable “hard” fibre. There are many varieties of the plant spread throughout the tropical and sub-tropical world, especially in Central America, but the most important on a commercial basis are AGAVE SISALANA (and its hybrids, the most common of which is known as 11648) and AGAVE FOURCROYDES (better known as henequen).
The East African sisal plant originated in the Yucatan, Mexico (and received its common name from the first port of export) and arrived in what is now Tanzania via Hamburg in 1893. A little later sisal bulbils sent from Kew Gardens were planted in Kenya.
After a difficult start sisal production in East Africa prospered and by the 1960’s Tanzania production alone totalled some 230,000 tons. Production in East Africa has contracted materially over the past three decades in response to the continuing movement in end products away from the low value agricultural twine market into considerably higher value more specialised end products, such as carpets, wire rope cores, dartboards, speciality pulps, plaster reinforcement and handicrafts.
Production is now approximately 20,000 tons per annum in Tanzania, 20,000 tons in Kenya and 12,000 tons in Madagascar. There is also production in Southern China of around 40,000 tons (very largely for domestic consumption) and smaller quantities in South Africa, Mozambique, Haiti, Venezuela and Cuba.
In Mexico henequen production (largely in the Yucatan peninsular) has fallen from a peak of about 160,000 tons in the 1960’s to about 15,000 tons today, all of which is converted into product locally.
The first commercial plantings in Brazil were not made until the late 1930’s and the first sisal fibre exports from there were made in 1948. It was not, however, until the 1960’s that Brazilian production really accelerated and the first of many spinning mills, largely devoted to the manufacture of agricultural twines, were established. Today Brazil is the major world producer of sisal at some 125,000 tons.
Traditionally sisal was the leading material for agricultural twine (“binder” and “baler” twine) but the importance of this is now tending to diminish (with competition from polypropylene and other techniques) although there is still a major business between Brazil and the United States.
Apart from ropes, twines and general cordage sisal is used in both low-cost and speciality paper, dartboards, buffing cloth, filters, geotextiles, mattresses, carpets and wall coverings, handicrafts, wire rope cores and macramé.
In recent years sisal has been utilised as a strengthening agent to replace asbestos and fibreglass and is increasingly a component used in the automobile industry, where its “naturalness” and environmentally friendly characteristics are greatly appreciated.
Sisal for export has for long been “graded” for length, decortication characteristics and colour. The main specifications are:-
No 1
No 2
No 3L
No 3
UG
Tow 1
Type 2
Type 3
Refugo
Bucha
Detailed specifications may be obtained by reference to the Company.