Coir fibers are found between the husk and the outer shell of a coconut. The individual fiber cells are narrow and hollow, with thick walls made of cellulose.
Together, India and Sri Lanka produce 90% of the 250,000 metric tons of coir produced every year
Coconuts are the seed of the palm trees. These palms flower on a monthly basis and the fruit takes 1 year to ripen. A typical palm tree has fruit in every stage of maturity. A mature tree can produce 50–100 coconuts per year. Coconuts can be harvested from the ground once they have ripened and fallen or they can be harvested while still on the tree.
White coir fibers are harvested from the coconuts before they are ripe. These fibers are white or light brown in color and are the smoother and longer fibers used to make flooring.
The coir fiber is
- relatively water-proof
- one of the few natural fibers resistant to damage by salt water
Retting is a curing process during which the husks are kept in an environment that encourages the action of naturally occurring microbes. This action partially decomposes the husk’s pulp, allowing it to be separated into coir fibers and a residue called coir pith. Freshwater retting is used for fully ripe coconut husks (brown coir), and saltwater retting is used for green husks (white coir).
By weight, coir fibers account for about one-third of the coconut pulp. The other two-thirds, the coir pith (also known as coir dust), has generally been considered a useless waste material. Although it is biodegradable, it takes 20 years to decompose. Millions of tons sit in huge piles in India and Sri Lanka.
During the last half of the 1980s, researchers successfully developed processes to transform coir pith into a mulching, soil treatment, and hydroponic (without soil) growth medium that is used as an alternative to such materials as peat moss and vermiculite. Before being compressed into briquettes for sale, the coir pith is partially decomposed through the action of certain microbes and fungi.