Hemp
 

How does Hemp fair environmentally and socially as a material?

Hemp (Cannabis sativa) has a lot of good environmental criteria 

  • it is fast growing and smothers out other plants (including weeds) therefore not requiring any application of herbicide. 
  • it appears to grow better in an organic system than in a conventional one
  • it grows well in cooler climates and little or no irrigation is required. 
  • It grows to between one and four metres tall and yields around 6 tonnes per hectare and 20- 30% of the plant is fibre. 
  • Hemp has far higher fibre yields than other natural fibres.

(Source: Kate Fletcher, 1999 www.demi.org.uk)

What can it be used for?

Property-wise hemp fibres are similar to flax or (linen) although slightly coarser and stronger. Hemp is suitable for a number of textile applications (as well as other applications including paper, building materials and composites) and particularly furnishing fabrics and 'bottom weight' clothing. It is frequently blended with other fibres such as cotton, silk or synthetics. Hemp is a realistic substitute for both cotton and linen. (Source: Kate Fletcher, 1999)

Hemp Canvas, Hemp linens, Hemp knits, Hemp stretch, Hemp blends and Hemp speciality knits are also now available - for more information visit: www.hemptraders.com

Narcotic properties

Hemp is known for its narcotic properties and this has meant that its cultivation is banned in many countries. Varieties with a low psychoactive compound Tetrahydocannabinol (THC) have been introduced and are now grown in the UK, among other nations. (Source: Kate Fletcher, 1999 www.demi.org.uk)

Fibre extraction

Fibre extraction is similar to that for flax (i.e. separation by retting) although hemp stems are ten times thicker and two to four times longer than those of flax. The traditional process of degumming hemp fibres from the stalk (retting) involves placing small bundles of stalks in water tanks, open retting ponds or running river water while the stalk rots and the fibres are separated from the woody core. Water retting is linked to water pollution as nutrients from the decaying stalks promote high levels of BOD and COD. Alternatives to water retting exist and include among others: dew retting, where plants are left to decompose on the ground with the right conditions of heat and moisture; and enzyme retting, in which enzymes are applied to the flax either in the field or in tanks and which avoid pollution problems associated with the traditional method. (Source: Kate Fletcher, 1999 www.demi.org.uk)