How to Spin Hemp Fiber

Spinning hemp fiber involves retting, decortification, softening, combing then spinning using wet or dry methods. Hemp fiber can be spun using any one of these three processes, cottonization, long fiber or tow processing.

Long Fiber Processing

Retting

• Hemp is harvested up to the mid flowering stage, which is then cut four to five feet from ground level, thus ensuring that both the seeds and the fibers are harvested. The plants are then left in the field to ret for about 10 to 20 days. Retting is done either by water or dew.

• Water retting is a process where the stems are placed in water, more specifically, in ponds, tanks or streams for approximately 10 days. While dew retting involves laying the hemp parallel in rows so the morning dew falls on the hemp. During this time, the stems are turned at least twice to allow them to ‘ret’ or rot evenly.

• In either method of retting, pectin within the hemp, that binds the fibers to the stem’s core is being released, which causing the fibers to separate. The process is complete once the hemp stalks have become white, divides easily into fibers, separates from the core, and stalks are dry.

Decortication

• At the end of the retting process, the fibers go through decortification. Some call this the grassing and scutching step. This is a drying process where the retted hemp is conditioned as well as freed from wood kernels by squeezing, breaking and scutching. More specifically, the stems are broken by passing them through fluted rollers.

• After this, the fibers are de-cored or “scutched” through a process of beating the stems with a beech stick. Alternatively, the stems may pass through rotary blades.

Softening and Combing

• After decortification, the hemp fibers are softened using a roller or softener. This causes the fibers to be suppler and softer.

• Then the softened hemp is combed. During this step, the long fibers are smoothed and “parallellized” with a hackling machine. While this is taking place, woody particles are being removed to produce a “continuous sliver” for the spinning step.

Spinning

• At the end of the combing process, the spinning process begins. This is where the slivers are drawn and doubled, then pre-spun into roving yarns using dry or wet processes. The wet spinning process involves “bobbin, drying and winding” while dry spinning is done through the spinning frames used for spinning flax.

• Next, the yarns are bleached with hydrogen peroxide then boiled in caustic soda for refinement. With these methods of spinning, two types of yarn are produced, one that is short and the other is long. Wet spinning produces softer yards; however, dry spinning produces yarn that is cheaper but coarser.

Tow Processing and Cottonization

• At the scutching and hackling step, the shorter fibers are spun into a coarse yard using the wet or dry process. At this stage, they are refined and parallelalized using carding machines. This is the towing process.

• Cottonization is where long hemp yarns are turned into a texture similar to cotton. It involves removing substances such as lignin and pectin from the yarn. This step uses “elementarization,” similar to what is done when making cotton.