Retting: Extraction of fiber
What is retting?
It is the process of separating and extracting fibers from non-fibrous tissue and woody stems by dissolving and breaking down pectin, gum and other mucus containing substances.
The fiber is mechanically extracted, washed, dried and sold. Although the harvest is good insufficient retting can result in poor fiber quality.
Methods of Retting:
1. Conventional method:
In this method we need to use suitable jack materials to immerse the defoliated bundles in clean or stagnant water. Mud or banana stems acts like jacks and produce dark fibers. Fibrous tree trunks such as water hyacinths can produce high quality fibers. After 18 to 21 days, the fiber was extracted manually using a single plant extraction method.
2. Chemical Retting:
This method involves boiling the fiber with acid, alkali or some salts at a certain temperature for 6 to 8 hours. Degraded products should be washed with clean water and excess liquor has to be removed by drying.
The retted stems should be broke. Urea, ammonium oxalate, calcium sulphate, magnesium phosphate has to be added in order to accelerate retting. The fibers obtained through this process are little thicker, rough and stiff.
3. Microbial Retting:
This type of retting can be used for ribbon or the entire system in case of water shortage with a minimal amount of groundwater. It involves
a. Insitu cooling of the entire plant.
It is done in a circular micro pond. It involves arranging of single layer straw bundles radially at the bottom of pond on the top of the polythene. The bundles are arranged radially up to three layers, with the base of plants oriented towards periphery. After that application
of microbial consortium at CFU (108- 1010) has to be done to the packs in the pond.
b. Mechano microbial retting
It comprises two different operations namely: Mechanical extraction of green strips by a motor driven bast fiber extractor or a manually opeatred fiber extractor and green ribbon setting with a microbial consortium.
Slow flowing soft water produces best quality fiber, but these conditions rarely occur. Water scarcity or lack of rain during harvest time forces farmers to harvest their crops in stagnant water resulting in inferior jute fiber. Apart from the conventional method of retting farmers can go for insitu microbial consortium which involves less time, reduced volume of water along with better quality.