Water-retting

Dew retting iuvolves the action of dew, sun, and fungi on the plants spread thinly on the ground. Dew retting takes 4—6 weeks, but the action is not uniform and it tends to yield a dark-colored fiber. However, it is far less labor iatensive and less expensive than water retting. It is commonly used iu regions of low water supply and accounts for 85% of the Western European crop, especially iu France, and also iu the former Soviet Union. 

Jibutilon theophrasti is a herbaceous annual plant produciag a jute-like fiber. The plant is native to the People s RepubHc of China and is commercially grown ia China and the former USSR. Because of its association with jute ia mixtures and export, it is also called China jute. The plant grows to a height of 3—6 m with a stem diameter of 6—16 mm. After harvesting by hand and defoHation, bundles of the stems are water retted and the fiber is extracted by methods similar to those for jute. The fiber is used for twiae and ropes. 

The colonists used one of three methods, and the law stated that a dealer had to specify the way the hemp had been retted. Water retting was considered to be the best method as far as the resulting quality of the hemp fiber was concerned. This involved immersing the hemp in a stream or pond for four to five days if done in summer, or thirty to forty days if done in winter. European hemp was usually water retted, but this was not generally done in America. Instead, Americans preferred winter retting. 

In contrast to the Russian method of production, Kentucky growers left the chopped cannabis stalks on the ground to become dew retted. Water retting was discouraged because Kentucky farmers believed that fish and livestock that drank from a pond in which hemp had been placed would be poisoned. Then, too, the water smelled like rotten eggs after hemp had been soaking in it, "which was considered unhealthy for slaves and twice as bad for whites."... 

Dew retting is similar in action to water retting, but slower. The stalks are spread out on grass and allowed to ferment, the necessary moisture being supplied either by dew, rain, or occasional watering. Sometimes the fermentation is started by water retting and the stalks are then taken out and laid on grass to complete the process. In this way a better colour is obtained. 

Flax fibers at the completion of the epidermis test. Retting is at the same stage as that shown in figure next above. The oortex is shown, after it has been swished to and fro in water. Retting is almost complete, and the outicle (c) is separated except at the leaf scars (2). 

Thus, warm water retting requires high capital expenditure and high water consumption. To combat the problem of high water consumption, and subsequent disposal, especially on plantation scale, aerobic bacilli are added (Rossii process) and the tanks are aerated. This results in lower concentration of volatile acids and a more alkaline solution, which enables the water to be reused with no limit. It also reduces the offensive odor otherwise given off during... 

It is a much simpler and more cost-effective alternative to separate the bast fibre from the plant straw [26]. The raw material for this procedure is either field dried or slightly retted plant straw. The bast fibres are separated from the woody part by mechanical means. Weather-dependent variations of fibre quality are eliminated. However, the produced green fibres are much coarser and less fine as compared to dew or water retted fibres. 

Retting is a process of the separation or loosening of bast fibres from its non-fibrous components [80]. Water-retting is performed by immersing the stalks of the fibre crops in water for a certain period of time. Water penetrates the central... 

Yilmaz [11] investigated the effects of alkali extraction treatment parameters on properties of corn husk fibers. Yilmaz [13] compared corn husk fibers produced by water retting, alkalization and enzyme treatment. Huda and Yang [7] produced composites from corn husk fibers and polypropylene (PP) and investigated their flexural, impact resistance, tensile and sound absorption properties. 

Bodros and Baley [37] studied the tensile properties of water retted nettle fibers. Bacci et al. [39] investigated fiber yield of nettle cultivation and quality of fibers extracted by alkalization. Bacci et al. [38] compared the effects of different fiber extraction method combinations including water retting, mechanical decortication and enzymatic treatments on resultant fibers chemical composition and tensile properties. Bajpai et al. [40,41] prepared nettle fiber-reinforced poly lactic acid (PLA) and PP composites by compression molding. Bajpai et al. [42] studied the effects of various environments on the tensile strength of nettle fiber-reinforced PP composites. 

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