Retting is a stage in the manufacturing of vegetable fibers, especially the bast fibers. It is a process that employs water and microbial action to separate the bast fibers from the woody core (the xylem), and sometimes from the epidermis as well.
In "water retting", plant stems such as flax, jute, hemp or kenaf are submerged in water, and soaked for a period of approximately 20 days to loosen the fibers from the other components of the stem. Retting can also be done by letting the cut crop stand in the fields in the wet Fall, called "dew retting". In either approach, bacterial action attacks pectin and lignin, freeing the cellulose fibres. The stems must be monitored during retting to avoid excessive degradation of the fibres, making it a very labor-intensive process.
Once retting is complete, the stems are then removed and washed, where they are typically subjected to mechanical processing to remove the soft tissue and then dried so that all that remains are the fibres.
See also: Jute cultivation