Sisal

Infobox on Sisal
Example of Sisal
Facts
Origin	Brasil Africa Asia
Stowage factor (in m3/t)	2,26 / 2,42 m3/t (bales
Humidity / moisture	5-12%
Ventilation	-
Risk factors	See text

Sisal

Description

Sisal (Agave sisalana) is an agave that yields a stiff ( white to yellow-white) fibre traditionally used in making twine, rope and also dartboards. The term may refer either to the plant or the fibre, depending on context. It is sometimes incorrectly referred to as sisal hemp because hemp was for centuries a major source for fibre, so other fibres were sometimes named after it.

Traditionally used for rope and twine, sisal has many uses, including paper, cloth, wall coverings and carpets.

Sisal plants consist of a rosette of sword-shaped leaves about 1.5 to 2 metres tall. Young leaves may have a few minute teeth along their margins, but lose them as they mature.

Propagation of sisal is generally by using bulbils produced from buds in the flower stalk or by suckers growing around the base of the plant, which are grown in nursery fields until large enough to be transplanted to their final position.

The sisal plant has a 7–10 year life-span and typically produces 200–250 commercially usable leaves. Each leaf contains an average of around 1000 fibres. The fibres account for only about 4% of the plant by weight. Sisal is considered a plant of the tropics and subtropics, since production benefits from temperatures above 25°C and sunshine.

Fibre is extracted by a process known as decortication, where leaves are crushed and beaten by a rotating wheel set with blunt knives, so that only fibres remain. In East Africa, where production is typically on large estates, the leaves are transported to a central decortication plant, where water is used to wash away the waste parts of the leaf. The fibre is then dried, brushed and baled for export. Superior quality sisal is found in East Africa. Proper drying is important as fibre quality depends largely on moisture content. Artificial drying has been found to result in generally better grades of fibre than sun drying, but is not feasible in the developing countries where sisal is produced. In the drier climate of north-east Brazil, sisal is mainly grown by smallholders and the fibre is extracted by teams using portable raspadors which do not use water. Fibre is subsequently cleaned by brushing. Dry fibres are machine combed and sorted into various grades, largely on the basis of the previous in-field separation of leaves into size groups.

Application

Traditionally, sisal has been the leading material for agricultural twine (binder twine and baler twine) because of its strength, durability, ability to stretch, affinity for certain dyestuffs, and resistance to deterioration in saltwater, but the importance of this traditional use is diminishing with competition from polypropylene and the development of other haymaking techniques, while new higher-valued sisal products have been developed. Apart from ropes, twines, and general cordage, sisal is used in low-cost and specialty paper, dartboards, buffing cloth, filters, geotextiles, mattresses, carpets, handicrafts, wire rope cores, and Macramé. Sisal has been utilized as an environmentally friendly strengthening agent to replace asbestos and fibreglass in composite materials in various uses including the automobile industry. The lower-grade fibre is processed by the paper industry because of its high content of cellulose and hemicelluloses. The medium-grade fibre is used in the cordage industry for making ropes, baler and binder twine. Ropes and twines are widely employed for marine, agricultural, and general industrial use. The higher-grade fibre after treatment is converted into yarns and used by the carpet industry.

Other products developed from sisal fibre include spa products, cat scratching posts, lumbar support belts, rugs, slippers, cloths, and disc buffers.

Shipment / Storage

Sisal fibre is usually shipped in bales. Sisal may be artificially or naturally dried. Moisture damage will cause discolouration and cause the fibre to turn black and give off a musty smell. If badly affected by water the product can go mouldy inside the bale, while drying out on the surface. Metal bands can rust and cause damage. Highly flammable, but not liable to spontaneous combustion. Requires good ventilation and should be stowed away from goods containing oils and fats. Care should be taken to determine whether any dark patches in the bales are caused by moisture, or by scorching during the drying process.

In order for the fibres not to break, sisal hemp is arranged lengthwise in bundles, which are grouped together unpackaged in bales and strapped with steel strapping or wire and only very occasionally with ropes (e.g. in Brazil). A piece of sacking is often inserted on one side for identification purposes.

Consult the IMDG Code (International Maritime Dangerous Goods Code) for overseas transport advice. Also see applicable MSDS sheet.

See also Fibres

Risk factors

• Self-heating / Spontaneous combustion; sisal hemp has an oil content of 8,7 - 20% (waxes).
• Odor
• Contamination
• Mechanical influences
• Toxicity / Hazards to health
• Shrinkage/Shortage
• Insect infestation / Diseases