The bundles of plants are then steeped in water so that the tissue or woody bark surrounding the hairlike flax fiber will decompose, thus loosening the gum that binds the fiber to the stem. The decomposition is called retting.
Retting only loosens the woody bark. If flax is not retted enough, the removal of the stalk without injury to the delicate fiber is difficult. If flax is over-retted the fiber is weakened. The retting operation, as well as other processes for producing linen fabric, therefore, requires great care. Retting can be done via different methods.
Types of retting:
- Dew retting
- Damp or pool retting
- Stream retting
- Tank or VAT retting
- Chemical retting
1. Dew retting:
The flax straw is spread on the grass and is exposed to the atmosphere for 3 to 4 weeks. This method produces strong dark flax gray in color.
2. Pool or damp retting:
It takes less time than dew retting (10-15 days). As stagnant pools of water are used this method sometimes causes over-retting, which is responsible for brittle and weak flax fibers. Pool retting darkens the flax giving it a bluish grey colour.
3. Stream retting:
This method for producing high quality flax fiber was used before but now is outmoded.
4. Tank or VAT retting:
The flax is immersed in wooden vats of warm water at temperature. Ranging from 25-30°c which hastens the decomposition of the woody bark. The flax is removed from the vats and passed between rollers to crush the decomposed bark as clean water flushes away the pectin or gum and other impurities. Linen produced by this method is more susceptible to mildew.
5. Chemical retting:
Chemical retting can shorten the retting process but chemicals will affect the strength and color of the flax fiber. Soda ash, oxalic acid are the chemicals used.