Eco-Tip: Hemp


We have profiled so many products made from hemp, thought it might be useful to provide a little background as to what makes it so significant. If hemp has a downside, its the mythology and hype that has attached itself to the name. It is hugely versatile but the claims that it can save the world, all on its own, are rather misleading. Industrial hemp is a hardy, fast growing herbaceous plant. The broad leaf blocks out sunlight inhibiting competing weeds, reducing need for heavy herbicide use. And these days a lot of hemp is grown organically, without need of any synthetic agricultural additives. It can reach heights of 15ft (4.5m) and can be ready to harvest in roughly 100-120 days after sowing. But rather than plant it year round, it performs best used a rotation crop, with soy, sorghum, etc, as its long tap root and leaf foliage return much needed nitrogen to ever worn-out soils. The seed, (which is really like a type of nut) is highly nutritious, being high in protein, carbohydrate and Essential Fatty Acids, as well as vitamins. The seed can be pressed to make oil. This has been used to produce fuel, lubricants, inks, cosmetics (most famously by The Body Shop) and so on. But hemp is more famous for its fibre. What makes hemp so strong is its long fibres but separating them from the pithy core of the stem has for centuries been troublesome. (Cotton once suffered a similar fate but the invention of the ‘cotton gin’ allowed it to overtake hemp in widespread fine textile production.) Hemp was traditionally retted (rotted) in fields after harvesting, to loosen the fibres. This can be done in factories but both options can be water intensive. In recent times an enzyme treatment has been speeding up the process and resulting in much softer textiles.

But even with such advances, hemp is still not a fine gauge fibre and is normally blended with cotton, silk, yak wool, Tencel, and recycled polyester to achieve apparel with a softer ‘hand’. Its benefits in textiles are durablity, strength, high resistance to UV light or mildew, and insulative qualities. You begin to see the reason why the word 'canvas' is derived from Cannabis sativa, hemp’s botanical name. And compared to the water and chemicals used on traditional cotton, it is a way more benign crop to begin with.

One of the key environment attributes of hemp is the ability of the whole plant to be utilised productively. The hurd or shive, which is that above noted pithy core, has many uses, from animal bedding to a concrete type product for house wall construction. Oil from the seed has been made into plastics to make furniture, CD cases and even a car. The fibres have been formed into carpets and upholstery. As noted here the long fibres can act as replacement for fibreglass, to make the likes of skateboards, a technology being taken up by the modern auto industry. A prototype hemp surfboard has been developed in the UK.

Hemp has not been allowed to be grown in North America since 1938 (except when it was required to support the war effort during WWII!) but 60 years later Canada resumed production. Romania and China remain two other key sources, although it is grown in many other countries, from France to Australia

In future posts we’ll obviously be bring more hemp products to your attention.

In the meantime, while there is no shortage of hemp sites on the web, you could start looking here: North America, Europe and Australia . Or visit the Hemp University or Global hemp news for more information. [by WM]

Hemp harvesting images via Ecolution