Methods of Extraction and Grades
In the Philippines, husk defibering is mechanized which involves two processes: the wet and the dry milling operations.
In the wet milling process, the coconut husks are crushed between fluted rollers called husk crushers before they are soaked in the retting pond for a minimum of 72 hours in order to facilitate the penetration of water through the exocarp. After soaking, the fibers are extracted through specially constructed machines called drums. Mature coconut husks are usually processed through this method.
The dry milling method, on the other hand, utilizes a special machine called down decorticator. The husk segment is disintegrated by the use of metal beater bars revolving at high speed followed by the use of sifters to separate the non-fibrous matter from the fiber. It is considered the most efficient method of extracting coir and is especially convenient in areas where soaking facilities are limited or are not available.
There are three main types of coir, namely: mat or yarn fiber, bristle fiber and mattress fiber. The mat or yarn fiber is usually known as the white fiber which is extracted manually from the retted husks of green coconut. The bristle fiber and mattress fiber, the two categories of brown fiber, are extracted from the husks of a mature coconut and are generally produced in the Philippines. Bristle fibers are the fibers left after the combing process with length of not less than 5 inches. On the other hand, the mattress fibers are the shorter fibers combed down after sifting the dust with length of not less than 2½ inches.
The grades of coir are determined by three qualities: strength, cleaning and color. The standard grades of coir are the following: