How is kenaf fiber made?
The suitable climatic conditions required for the growth of the kenaf plant are warm climates. The plant generally grows up to a height of 3-5 metres and the diameter of the stalk is about 3-5 centimetres. The stalk of the kenaf plant has two regions i.e. outer fibrous bark and inner woody core.
The steps involved in the harvesting of kenaf fibers are as follows:
The correct time to harvest the kenaf crop is when about ten flowers appear on the plant and the plant has attained the maximum height followed by retting of bark and fiber extraction.
However, if the harvesting is done early when the plant is young then the fibers obtained are of low quality, soft and low in strength and the extraction becomes difficult. The harvesting time is of great importance in order to obtain good quality fibers.
Harvesting of mature kenaf stalks is done using hand with the help of a sickle or with the help of a cutter attached on a tractor which chops off a bundle up to a height of about three feet. After which the stems are arranged in the bundles and a then defoliated i.e. leaves shed off.
Retting or rotting is a process of removal of kenaf fiber bundles from the outer woody stalk. fiber bundles are present beneath the bark and held together by a gummy substance, in order to separate the fibers, the stalk is immersed in the water. The bundles of stalks are submerged in the in-stream, pool or pond, ditches and weighed down to keep them immersed all the time during the process of retting.
Retting can be carried out by various methods such as dew or field retting, stream retting, pool or pond retting, vat retting and chemical retting. The time duration required for the retting process is 5-15 days and the temperature of the water should be around 80. The method of renting also has a certain influence on the quality of the fibers obtained.
When the retting process is complete the bundles of fibers become soft and loosen because of the action of bacteria that grows on them. After which the stalks are thoroughly rinsed so as to remove dirt, gum, extraneous plant materials and retting residues that may be present and sun-dried in fields.
• Scultching and Combing:
The bundles of the stalk are then beaten against the wooden mallets lightly to extract the fibers from the stalk. The scutched fibers are then pulled through a series of iron combs to increase the fineness. The combed fibers are then spun into yarns.
At this stage often the fibers are graded on the basis of colour, lustre and the organic matter that may have been left.
• After the fibers are extracted, they are spun into yarns but kenaf fibers are woolly and are a bit difficult to spin into yarns. Often the kenaf fibers are also blended with cotton depending on their end-use. The kenaf yarns then may be woven or knitted as per the need.