Coir is extracted from the protective husk of coconuts through a procedure called ‘wet processing.’ This method has traditional and modern adaptations, and the type used depends on where the coir is being produced.
The process of extracting the coir fiber is called ‘wet processing.’ In the traditional practice, husks are separated from the coconuts and soaked in lagoons or brackish waters for up to a year. Soaking allows the husks to ferment, soften, and separate. The fibers are then washed, dried, and manually cleaned. This method is labor-heavy and time-consuming.
Mechanical techniques, which are becoming increasingly environmentally friendly, are used to shorten the soaking and processing times. After five days in water, the husks can be crushed to break up their fibers. Drums are used to separate the coarse fibers from the short, woody parts, which are then washed, dried, and cleaned.
Coir is available in brown and white fibers. Brown fiber, which is the most common, comes from mature, ripe coconuts. Brown fiber contains high levels of lignin, which prevent it from being easily dyed, but it also has less cellulose than cotton and flax. White fiber, which is finer, comes from immature, green coconuts.
The quality of the fibers depends on which extraction process was used. Normally, the fibers measure between 50 and 150 millimeters in length and are capable of stretching beyond their elastic limit without breaking. Coir fibers are resistant to degradation and salt water.
Bleaching and Dyeing
Coir fibers can be bleached or dyed to make them more appealing. Brown fibers, due to their high lignin content, are less susceptible to dyeing, while white fibers can be dyed and bleached more easily.
Up to 20 percent of the coir fibers used for mats, rugs, and carpets are bleached using either hydrogen peroxide, acid, or bio-bleaching. Bleaching can reduce or entirely eliminate colors.
Dyes allow coir fibers to be used in an increasingly diverse set of final products. In the industry, there has been an increased focus on using environmentally safe dyestuffs and meeting high-quality standards for dyeing practices.
Printing on finished products has also become more popular. The most common method of printing uses stencils and sprayed dyes. Developments in technology have made it much easier to stencil designs on coir mats.
To improve the texture of coir products, some suppliers will soften the coarse and hard fibers that often protrude from finished products by using chemicals, vegetable oil, and bio-softening techniques. As a subjective measurement, softness is difficult to gauge, and the perception of softness does not always align with the methods that were used. Research on this step of wet processing continues to be done.
Coconuts thrive in wet, tropical climates, which make air drying almost impossible. Instead, coir processors use drying equipment. When energy prices are low, the most efficient method is hot air drying. However, drum drying is also used.
The steps involved in wet processing vary slightly between coir-producing countries. This was a general overview of the wet processing method.