**3. Bast fiber processes**

Flax/hemp fiber extraction from the stem is strongly connected to the retting process, which is usually a microbiological process that uses bacteria and fungi strains applied in order to degrade pectin and lignin, remove woody part of the stalk, and divide the technical bundles to smaller fiber complexes. There are several retting methods: water, dew, chemical, enzymatic, and physical retting. The use of the three


*Chemical composition of fibers coming from different varieties of flax controlled in sequence stages of fiber processing; different varieties of hemp extracted with use of dew retting as well as hemp fiber Białobrzeskie variety obtained by different methods of fiber extraction: Decortication, osmotically degumming, and water retting [19].*

## *Natural Fiber*

last listed methods is limited to small application; these methods have not been used in large industrial scale yet.

The traditional water retting process delivers the best quality of long fibers characterizing by high cellulose content and low lignin and pectin share resulting in low fiber linear density, good mechanical properties, and good spinnability. Water retting used to be the most recommended process for bast fiber dedicated to textile production. Nevertheless, owing to the generation of large amounts of wastewater and high pollution of soil and air, this method has been abandoned in Europe and many other countries in the 1960s [20–22].

The second retting method delivering good quality of long fibers is dew retting; nevertheless, the process effectiveness and quality of the fibers are not stabile because it depends on weather conditions prevailing in time of the stalk remaining on the field.

The method of fiber extraction, which allows one to avoid the retting process, is the decortication of raw straw collected when the plants reach proper fiber maturity. Decortication is a mechanical process giving one type of insufficiently dividing fibers with high impurities content.

The method of flax/hemp fiber extraction determines further technological chain of fiber processing and spinning. The simplified schema of value chains of bast-fiberbased textile for both the methods of fiber extraction, e.g., with the use of retting and with application of decortication, is presented in **Figure 5**.

Flax/hemp stalks after retting are mechanically breaking and scutching to separate fibers from the woody part of the plant and dividing big complexes of fibers to smaller ones. The processes are efficient due to the decomposition of noncellulose components made by bacteria and fungi activity during retting. As a result of scutching, long fibers and scutched tow are produced. Long fibers must be mechanically cleaned and straighten as well as laid parallelly toward each other with the use of hackling machine dedicated only to bast fibers processing. The hackling process delivers sliver of long fibers and mass of short fibers, e.g., hackling tow. Both types of fibers are spun with application of linen spinning system, long fibers with the use of wet spinning, and short fibers by wet or dry spinning.

**Figure 5.** *Simplified value chain of hemp/flax textile product [own elaboration].*

Second value chain determined for decorticated fibers allowing avoid of retting has to employ the wet degummed process to remove lignin, pectin, and partially hemicellulose in order to make it possible to divide the bast fibers for elementary ones. Using this system, only one type of fibers is produced; it is not possible to obtain long and separately short fibers. Degummed decorticated fibers are cottonized to make the fibers suitable for spinning with the use of the cotton spinning system [23].

The yarn prepared by using the cotton spinning system, including decortication, and the linen spinning system can be used for textile purpose.
