Sisal is a relatively recent natural fibre; it was first used towards the end of the 19th Century and flourished in the early 20th Century. Despite a decline in its use, it still constitutes one of the most important natural fibres on a worldwide scale. Sisal plants are preferably cultivated in tropical and subtropical climate zones, which tend to have a consistently hot climate all year round.
Fibres from the leaves of certain agaves are referred to as sisal, particularly those from the sisal agave (Agave sisalana). The plant is originally a native of Mexico - nowadays the main producing countries are Brazil, Kenya, Tanzania, China, Madagascar and Mozambique. In East Africa and Madagascar, the proportion of hybrid plants predominates. Only the original plant - Agave sisalana - is cultivated in Brazil. These fibres are characterised by their very high tensile strength.
The fibre separation (separation of the fibre from the leaf tissue), takes place mechanically (either with the help of stationary or mobile machines). The use of water to extract the fibres from the leaf is an essential factor for the quality and ultimately also for the intended use of the fibres.
The proportion of dry fibres in the total weight of the fresh leaves is only about 2 to 5%.
Dr Hindorf introduced the first sisal agaves to German East Africa from their region of origin Yucatán (with the harbour village Sisal). These became the mother plants for the large-scale sisal industry in East Africa. Sisal fibres were still being cultivated in Indonesia until the mid 1960’s and in Angola until the mid 1970’s.
In 1908, the CORONA machines (Krupp-Grusonwerk, Magdeburg) were first used for extracting sisal fibres in what is now Tanzania. These and similar machines from the brands STORK and ROBEY, are still used in East Africa and Madagascar to this day. These stationary machines are designed for the production of large quantities. With the help of knife-edged “beater drums”, high-pressure water separates the fibres from the pulp and leaf debris. Depending on the construction and size, these machines consume approx. 35,000 litres of water per hour. Afterwards, the fibres are dried, brushed and then according to the classification, pressed into bales.
Stationary machines for the removal of fibres are only used where sisal plants are cultivated in large, connected plantations which ensures a good utilisation of the machines - therefore in East Africa and Madagascar.
In Brazil, on the other hand, (with one exception), there are no large plantations and sisal is grown by smallholders. Approx. 90% of the sisal production in Brazil takes place in the so-called Sertão nordestino, a semi-desert landscape inland of the federal state Bahia (in the North East of Brazil). Here, fibres are removed with mobile machines directly on the fields - without the use of water, which is rather scarce in this region.
In East Africa, the industrial use of sisal fibres began as early as the beginning of the 20th Century. Production only became commercially significant in Brazil between 1937 and 1941. Brazil already started exporting sisal in 1946 and only five years later, in 1951, it was the second largest producing country. As of 1964, the market for sisal gradually slumped due to increasing competition from synthetic fibres and production continued to fall.
Although annual global production of sisal and henequen was still close to 800,000 tonnes in the early 1970’s, it decreased to around 200,000 tonnes by the turn of the millennium. Only recently has the use of sisal started to increase again due to new applications and rising prices for crude oil as a basis for synthetic fibres.
Fibres from the agave sisalana are characterised by their very high tensile strength and are preferably used for the production of ropes as well as compression and harvest yarns (agriculture). The finer fibres of the hybrid have a similarly high tensile strength - they can be spun into much finer yarns, however. Nowadays, these finer yarns (dyed and undyed), are also used for rug production.
The cellulose content of the fibres lies between 55 and 65%, which is why the fibres are also used for the production of paper pulp.