Flax is probably the oldest textile fiber known to mankind. Flax, which is one of nature’s strongest vegetable fibers, was also one of the first to be extracted, spun and woven into textiles. Flax comes from the stem of an annual plant Linum usitatissimum, which grows in both temperate and sub-tropical climates. Presently, two types of flax plant are grown, for fibers and for seeds (oil). The seeds of the flax plant are crushed, yielding flax oil known commercially as linseed oil. Within the inner bark there are long, thin, thick walled cells that compose the fibre strands. Only about one quarter of the stem is fiber.
The fibers are held together by woody material and cellular tissue that must be removed to liberate the final fiber. The flax woven fabric is also called linen. Linen fabrics are valued both by designers and users for their smoothness, silky gloss, durability, comfort, and easily recognizable, specific appearance that denotes their natural origins.
Hemp is overall a courser fiber than flax, being darker in color and difficult to bleach. Hemp fiber is strong and will hold its shape, stretching less than other natural fiber. This keeps the garment from stretching out or distorting with use. It is more mildew resistant than cotton, it is also naturally resistant to mould; The cross-section of hemp is polygonal and the lumen is broader than that of flax. Dry hemp fibers have high cellulose content, approximately 75%; lignins are lower at 3.6%, compared to jute. Other components are hemi-cellulose about 17%, fats and waxes 0.8%, water solubles 2.0%, pectins 1.0% and lignins 3.6%. The major applications of hemp are in the manufacture of ropes, twines and cordages. More recently however there have been garments manufactured from blends of hemp with cotton. High quality hemp can be used as a substitute for flax.
Difference between Flax and Hemp Fiber:
Differentiating flax and hemp is a long-time analytical problem, which is becoming more and more relevant with the wider loading of bast fibers. Flax and hemp are very similar fibers in all aspects, and their differentiation is often controversial. In this article, the literature is described for the classic methods of differentiating these two types of fibers.
Flax (in fiber form) is practically undifferentiated from hemp, which threatens possible confusion with the latter, which is considerably different in price. Flax and hemp are cellulose fibers produced from stocks of row material. Their properties are similar and they are scarcely differentiated at the fiber form. Analytical differentiation is complicated by strong interventions into these fibers during the textile treatment, which is similar in both flax and hemp: the fibers are separated, blanched, and undesirable additions are removed.
The morphological characteristics mentioned in below comparison Table can be used for microscopic differentiation of flax and hemp. The observation is mostly oriented towards the observation of the shapes of the fiber’s cross-sections and fiber ends at the longitudinal view. This method is time-consuming (requiring preparations to be prepared), the appreciation of the characteristics observed is rather subjective, and it also requires considerable experience. An advantage is the fact that the shape of the elementary fibers does not change during the processing.
Various morphological structures of flax and hemp are exhibited by the diverse extents of the swelling property of the fibers. The flax swells uniformly and relatively rapidly, the tube in the non-blanched fiber contracts in a serpentine fashion, and it resists the solvent. The hemp swells slowly; during this process the tube in the raw fiber often obtains a typical periodic-shape. The swelling of the flax and the hemp has been photographically documented by Koch and Felix. For observing fibers it is necessary to use the microscopic technique.
Hemp contains more lignin and non-cellulose portions than flax. On this basis, a group of tests has been prepared in which the dyestuff of the agent is e.g. absorbed only by the lignin part of the fiber, for example, or when the agent reacts with the non-cellulose parts of the fiber depending on the color compound applied. Dyeing tests are especially applicable to raw fibers before eliminating non-cellulose substances from fibers (preliminary finish or otherwise); after their elimination, the fibers will not color. The methods are easily executed, and their results are apparent by visual evaluation even without microscopic equipment.
Indirect method of determination of fibril slope in the flax and the hemp. Flax and hemp have different orientations of fibril bundles in the fiber. Indirectly, this fact is verified by the opposing behavior of flax and hemp in polarized light (as directed from above), and by the possibility of distinguishing the fibers by X-ray diffraction.
From the analytical aspect, the orientation of the fibrils at the hydration and dehydration of lamellas is important. During these processes, changes to the geometry characteristics of the fibril bundles occur. These changes are macroscopically expressed by the fiber’s effort to turn, and so eliminate the internal stress at the sorption (or desorption) of water. Sonntag used this method for the analytical distinction of flax and hemp.
The so-called ‘Twist test’ method for differentiating flax and hemp is founded on this basis, the merit of which is the observation of the spontaneous twisting of the fiber as it dries. If wet flax is held by one end and dried, then its free end, which is oriented towards the observer, will turn clockwise. Under the same conditions, hemp will turn round in the opposite direction. The direction of twisting is characteristic for both flax and hemp, whereas cotton fibers twist in various directions during this test. Ramie twists as flax.
Comparison of the properties of flax and hemp fiber:
|65-87% (blanched, up to 98%)
|Under 80% at technical ripeness
|Greater than flax
|1460 – 1500 kg.m-3
|Length of elementary fibers
|3 – 60 mm
|4 – 55 mm
|Shape of cross-section by elementary fiber
|5- to 7-sided, with sharp peaks
|Polygon with rounded peaks
|0.25 – 0.33 tex
|0.25 – 0.38 tex
|30 – 50 km
|Elongation at break
|1 – 2.5% dry
2 – 4% wet
|Shape of lumen
|Small, less apparent even at the dotted form
|Broad, dashed (rarely circular)
|Ends of the elementary fibers
|Dull or forked
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.