Processing

Historically, hemp is one of the oldest plants grown for its fibre, and used as a basic raw material for the production of rope, canvas and clothing. During the last decade, there has been a revived interest in hemp as a renewable resource. It has been intensively promoted by different institutions in Europe and has become an economically interesting crop thanks to European Community subsidies, resulting in a vast increase of cultivated areas.

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.

Most of the manufacturers around the globe use modern methods which rely upon chemical processes because they are faster, less labor-intensive and therefore less expensive. But their hunger for profits only undermines the health of people, the ecology and the environment.

CAVVAS, on the other hand, stayed comitted to our country’s traditions and to our mission to be the manufacturer of the most eco-friendly European hemp textiles. In Romania, hemp fabrics have been woven for at least 10,000 years. The traditional methods have evolved during the centuries but the processes remained friendly to the environment and to the wearer because we preserved mechanical processes as opposed to using chemical ones.

Hemp is environmentally friendly in many ways. Hemp grows well without herbicides, fungicides, or pesticides and, therefore, it can displace the use of cotton, which requires massive amounts of chemicals harmful to people and the environment. The production of cotton consumes 50% of the pesticides sprayed in the entire world. Hemp has a deep root system that helps to prevent soil erosion, removes toxins, provides a disease break and aerates the soil to the benefit of future crops. Hemp is an environmental, renewable, reusable and recyclable resource.

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 are:

 

1. 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.

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 arround the world 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.

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 30-45 cm, 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.

At CAVVAS Limited, 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. Water retting is conducted near a sewage treatment plant to treat the waste water. Water retting produces a more uniform and higher quality fiber.

 

2. 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 textile products. The main difference 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.

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.

Because hemp retted using traditional organic methods retains the long fibers in hemp, at CAVVAS Limited specialized spinning machineries are used to process the long fibers into spun yarn. The additional expense of the specialized spinning machines and the greater cost to operate, have discouraged other existing textile manufacturers to expand their operations into the production of long fiber hemp yarns.

 

3. CLEANING & SOFTENING

As an ecologically-minded hemp textile manufacturer, we have been researching and developing new methods to produce chemical-free, organic hemp fabrics that are soft to the skin and yet retain the exceptional durability of hemp.

After the weaving process, the resulting loomstate fabrics are washed with ecological detergents or sometimes just with plain water which is afterwards treated. Drying is made by using constant temperatures. The temperature level differs from fabric to fabric, depending on its thickness, in order to avoid burning or weakening the strength of yarns’ structure.

The hemp yarn used for knitted fabrics is dyed by a specialized dyeing facility with internationally certified reactives.

Same as in the woven fabrics’ case, the softening process implies adding certified fiber-reactive substances which provide a unique softness to the fabrics. The boiling is made at constant-level temperatures, the entire process being closely supervised in order to obtain a beautiful shade all along the fiber’s length.

Our eco-friendly softening reactives have been developed through years of research by foreign partners such as Bezema AG (Switzerland). For more information please access Bezema’s official website: www.cht.com

 

4. DYEING & FINISHING

All dyes utilized in the manufacturing processes are ecological certified and the facilities used for various phases of our yarns and fabrics processing are ISO certified.

Each stage of the finishing process follows extremely strict parameters which depend on the yarn’s or fabric’s thickness.

After the fabric has been washed, dyed, softened, waterproofed if there is the case or if the client required this, the fabric reaches the pre-final stage which plays a very important role.

The fabric is sanforized. This process implies feeding the fabric into a special sanforizing machine and therein moistening the cloth with steam. A rotating cylinder presses a rubber band against another heated rotating cylinder, thereby the rubber band briefly gets compressed and afterwards shrinks to its final size. The fabric to be treated is transported between the rubber band and heated cylinder and is forced to follow this brief expansion and recontraction. The purpose of this process is to open up the fiber’s molecules and, under pressure, fixate them. Thus, the yarns are finely arranged within the weave, resulting a higher strength level of the fabric.

The final phase of the finishing process, before the fabric reaches final consumers or our designing department, consists in quality control. This implies analyzing the fabric meter by meter in order to identify potential processing errors and make adjustments, if necessary. If the fabric presents weaving faults, it is used in-house avoiding the damaged sections, thus keeping to the minimum the quantity of scrap fabric. In case of finishing faults, the fabric is returned and corrected according to our standards.