Manufacturing 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 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.