Is the name sisal unfamiliar to you? If you’ve ever played darts, you’re familiar with it. Sisal is that woody, almost cork-like material that dartboards are manufactured from. It has many other uses too, and industrial engineers are excited about its many potential applications.
What Is Sisal?
Sisal fibers are harvested from the sword-shaped leaves of the Agave Sisalana, a large succulent that’s native to Mexico’s Yucatan peninsula. Sisal is known as the coarsest of the natural plant fibers. The Agave Sisalana renders strong, flexible fibers that were used for centuries by the Mayans in everything from rope and twine to hammock cloth.
The Agave Sisalana is a sterile hybrid of a succulent called henequen. Prosperous colonials in the early part of the 19th century became even richer by selling the plant’s fibers to manufacturers in the United States and Europe. These manufacturers used the fibers to make rope, string and similar products. The port the bales of fibers were shipped from was called Sisal, and pretty soon the fiber itself came to be known as sisal.
Over its seven to ten year lifespan, each Agave Sisalana plant produces between 200 and 250 commercially usable leaves. Each leaf contains 1,000 or so sisal fibers. These fibers only constitute a very small portion of the plant, perhaps four percent of its total weight. Harvesting typically begins three to five years after the succulent is planted. Leaves are harvested close to the stalk as soon as they reach their full length. The first harvest typically produces 60 leaves; subsequent harvests, done yearly, produce 30 leaves.
Sisal is naturally flame-resistant and it absorbs sound, which makes sisal rugs a great addition to your home. Sisal is also a poor electrical conductor, so it repels static electricity.
What Are Natural Fibers?
The United Nations’ Food and Agriculture Organization defines natural fibers as “renewable fibers from plants or animals, which can be easily transformed into yarn for textiles.” In contrast, synthetic fibers are polymer filaments that are created through chemically processing petroleum monomers.
In the short run, it may seem as though synthetic fibers are cheaper to produce than natural fibers. If you look at energy use over the lifetime of a textile product, however, it’s clear that it requires a lot more energy to produce a synthetic fiber than it does a natural fiber, and that synthetic fibers leave a far larger carbon footprint.
Synthetic fibers are also less healthy than natural fibers. Volatile chemicals are used in their manufacture, after all, and many synthetic fibers radiate small amounts of volatile organic compounds throughout their functional lifespans that no amount of washing will get rid of. Exposure to these chemicals may lead to allergic reactions involving respiratory and skin symptoms in people who are sensitive to such compounds. In some particularly sensitive people, these volatile compounds may even disrupt the normal functioning of the immune system.
Additionally, synthetic fibers don’t move heat and moisture away from the body. The result can be uncomfortable chafing or a buildup of sweat, which can become an excellent medium for fungal and bacterial infections.
Sustainable Sisal
The Agave Sisalana absorbs more carbon dioxide than it produces, which could makes sisal production part of a solution for climate change. Sisal is also completely biodegradable.
The plant has an extensive root system, which means it can be used in watershed management to prevent soil erosion in areas where flash floods constitute a threat.
Sisal fiber is only a small portion of the Agave Sisalana; organic wastes after the fiber is harvested can be used to produce animal feed and fertilizer, or to generate bioenergy.
What Are the Textile and Product Applications from Sisal?
Sisal is too coarse to be worn close to the skin, so it is not used to make garments. Traditionally, sisal was used in the manufacture of rope and twine, but competition from synthetic polypropylene fibers has caused that particular market to all but dry up. Fortunately, many other markets are opening. Sisal has been used to make floor mats, area rugs, placemats and upholstery stuffing. It’s famous as the material that dartboards are made from. It’s also used in specialty paper, filters and cardboard. Sisal is often used in buffing cloths because it’s strong enough to polish steel but soft enough not to scratch it.
Some of the most exciting new applications for sisal lie in the industrial sector. Sisal is increasingly being deployed as part of the plastic composite materials used in automobile components like door panels, seat backs, headliners, package trays, dashboards, and trunk liners. Engineers are also investigating the use of sisal in motor vehicle brakes as a replacement for asbestos.
Where is Sisal Produced?
The highest quality sisal comes from plants grown in humid conditions with plenty of sunshine at temperatures between 20 to 28º C. The covering of the sisal plant is naturally thick and leathery, so it is very resilient to pests and disease, and doesn’t require extensive husbandry to prosper so long as it’s grown in somewhat alkaline soil.
Approximately half the world’s sisal supply is grown in Brazil. Other major producers of sisal fiber include Tanzania, China, Kenya, Madagascar, Haiti and South Africa.
The environmental benefits of using sisal are indisputable: The fiber is 100 percent biodegradable, and sisal products can be recycled and turned into paper before they are discarded. As the oil used for producing plastics becomes more expensive, combining renewable fibers like sisal into molded plastic parts will help keep costs down. The Ford Motor Company is now investigating an injection moulding technique for auto components that would allow 30 percent of the plastics used in parts like battery trays and engine junction box covers to be made from fibers like sisal and hemp.
Most importantly, though, the use of sisal products represents a personal commitment to sustainability, and to the importance of conserving the earth’s resources for generations yet to be born.
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