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Manufacturing of Hemp Fabric:
Because of its unique nature, hemp can easily be grown organically. In creating healthy, organic clothing, growing is only half the picture. Processing fiber into fabric and fabric into garments must also be done using processes that are healthy
to the individual, the environment and the society. Hemp fabrics have been woven for at least 10,000 years.
The traditional methods have evolved during the centuries but the processes have remained friendly to the environment and to the wearer because they have remained mechanical rather than chemical. Many hemp fabric manufacturers, especially in
Eastern European countries such as Romania and Hungary, use the traditional mechanical process that utilize modern machinery specially designed for hemp processing.
Modern methods are being developed which rely upon chemical rather than mechanical processes because they are faster, less labor-intensive and therefore less expensive. The hunger for profits undermines the health of people, the ecology and the
environment.
We will examine the basic processes and how they are performed under modern chemical methods and under traditional organic methods. The basic processes involved in creating hemp fabric for garments are:
Separating the fibers;
Spinning and weaving these fibers into yarn;
Cleaning and softening;
Dyeing and finishing;
SEPARATING FIBERS. Retting begins the process of separating the long bast fibers from the non-fiber portions of the bark and is completed during the decortication and hackling steps.
Chemical Methods. Modern chemical hemp processing makes use of enzymes, chemicals and even ultrasound to rett, or separate, the long bast fibers from the plant for spinning into yarns for fabrics.
Some hemp fiber manufacturers in China use modern physical-chemical methods which create a cotton-like short fiber. This creates a short fiber hemp called "cottonized" hemp or "flock" hemp. But the quality of the resulting yarns
still needs improvement, especially in the area of long-term wash-and-wear resistance. This may be due to chemical processes removing most of the natural binders lignin and pectin from the hemp fibers.
Organic Methods. Traditional hemp processing of plants into yarn for fabrics relies on natural and mechanical processes to separate the long fibers from the plant for spinning into yarns. Two traditional types of retting are field and water
retting. Basically, retting is the microbial decay of pectin, the substance that glues the fiber to the woody core of the hemp stem.
In traditional field retting, the process is bacterial, aided by dew or rain. Field retting will involve chopping of the stalk into lengths of 12-18 in., turning of the windrow at several-day intervals, and baling when retted and dry. Field retting
takes 14 to 21 days to complete depending upon the weather. Ecologically acceptable water retting should be conducted near a sewage treatment plant to treat the waste water.
Water retting produces a more uniform and higher quality fiber but the process is time consuming and costly and can pollute the body of water being used for the process.
Another process being developed is green retting or mechanical retting. This process uses a machine at the field to mechanically separate the fiber from the hurd. Machinery for this process is currently being designed and tested by various
companies throughout the world.
In Eastern Europe, the raw fiber is separated by traditional methods of water retting, breaking, scutching, and hackling. This produces the high quality long fiber that is first spun on special long fiber spinning equipment (up to 14 Nm) and then
woven.
SPINNING & WEAVING. Spinning takes the hemp fibers and spins them together to produce a long continuous strand of yarn. This yarn is then used to weave or knit the fabric used in hemp garments and textile products. The spinning process
is essentially the same for hemp that has been processes using chemical methods or using organic, chemical-free methods. After all, spinning is spinning.
What is different in the spinning process between hemp fibers processed using chemical methods and fibers from organic methods is generally the length of the hemp fiber and the spinning machines that are required to spin the long fiber organic hemp
and the short fiber, chemically processed hemp. Textile manufacturers who simply want to get on the hemp bandwagon as cheaply as possible are more likely to also use chemical methods to process their hemp fibers.
When the hemp fabric is washed and shrunk, the weave will naturally close up. This is in direct proportion to the degree of shrinkage obtained. In practical terms, this means that identically woven fabrics may appear different if one of them has
been washed, dyed, bleached, or shrunk.
Chemical Methods. Unlike long fiber hemp, short fiber “cottonized” hemp created by chemical processing can be spun and finished on slightly modified cotton or wool processing equipment, so that the existing and cost effective
infrastructures for the processing of cotton and wool could be used. This allows textile manufacturers to begin processing hemp fabrics quickly and with a lower cost to enter this new market. Several textile equipment manufacturers are currently
conducting spinning trials using short fiber hemp on modern rotor spinning machines.
Organic Methods. Today’s fiber spinning machines have been designed for the shorter fibers found in cotton and wool. Because hemp retted using traditional organic methods retains the long fibers in hemp, specialized spinning machinery is
required to process the long fibers into spun yarn. The additional expense of the specialized spinning machines and the greater cost to operate, have discouraged existing textile manufacturers to expand their operations into the production of long
fiber hemp yarns.
CLEANING AND SOFTENING. Among those familiar with hemp fabric from years ago, hemp has a reputation as being stiff and even abrasive to the skin. The naturally long and strong fibers created fabric that was stiffer and heavier. Hemp textile
manufacturers have sought ways to improve the softness of hemp fabric.
Chemical Methods. Chemical processing uses heavy caustic sodas and acid rinses to pulp, clean and soften the fiber. Unfortunately this strips the fiber of much of its rich character and strength and produces hazardous,
environmentally-destructive waste. Solvents are used to scour and clean the fabrics.
Organic Methods. Ecologically-minded hemp textile manufacturers have been researching and developing new methods and machinery to produce chemical-free, organic hemp fabrics that are soft to the skin and yet retain the exceptional durability
of hemp. ECOLUTION®, an environmentally-friendly grower and manufacturer of hemp products that is based in Romania, has pioneered many of the new methods for producing superior hemp garments and products. They have accomplished this by refining
the hackling stage of their combing technology and the banding stage in the fiber preparation.
Because of its low lignin content, hemp can be pulped using less chemicals than with wood. Its natural brightness can obviate the need to use chlorine bleach, which means no extremely toxic dioxin being dumped into streams. A kinder and gentler
chemistry using hydrogen peroxide rather than chlorine dixoide is possible with hemp fibers. All scouring and cleaning agents are biodegradable, rather than solvent –based.
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