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How is Hemp Made

Page history last edited by Jenna 11 years, 6 months ago

Primary Audience

 

Secondary Audience

 

 What is Hemp?

 

The industrial form of the plant Cannabis Sativa L., more commonly referred to as “hemp,” is a resilient fibrous plant that can be used to make many different products.  Hemp fibers can be used to weave high-quality cloth, to create paper pulp, and can be condensed into oil for inclusion in health and beauty products.

 

To figure out how Hemp is made, we will explore answers to these questions:

 

How is Hemp Planted?

How is Hemp Harvested?

How is Hemp Refined?

 

How is Hemp Planted?

 

Hemp is planted by sowing Cannabis Sativa L. seeds in fertile, firm soil with the aid of standard farming manure. A mechanical seed roller is run through the desired area, creating many small holes for the hemp seeds to nestle into.  The seeds are placed closely together to result in a tightly-packed “forest” of uniform hemp plants for optimal growth and end yield.  There are usually a minimum of 250 seeds per square meter of space which are sown in rows that are four inches apart[i].  

 

Hemp can be grown in nearly any climate, though it can be a picky crop when it comes to sunlight.  Hemp is a short-day plant, which means that it cannot withstand exposure to sunlight for over 13 hours[ii].  This doesn’t seem to be too great an obstacle for many industrial hemp farmers, however; hemp crops have been known to grow in many different areas of the world and can flourish throughout most of the United States.

 

 

 

Figure 1 - The shaded regions are ideal for the growth of successful hemp crops

 

 

How is Hemp Grown?

 

From the time that Cannabis Sativa seeds are sown, hemp requires 110 days, or roughly four months, to reach maturity[iii]. Hemp requires very little human attention after it is planted, but there are a variety of obstacles that the plant must overcome to achieve successful growth.

 
Weeds

Due to the crowded nature in which hemp is planted, it is very difficult for weeds to survive the thick root system and shade created by a properly-sown hemp crop[iv].  Weeds are usually a significant drain on a plant’s resources – they use vital water and nutrients that could otherwise be utilized by the crop – but hemp does not seem to encounter that problem.

 

 

Figure 2 – A hemp crop at week 12 of development

 

 

Pests

Like many other crops, hemp is susceptible to the infiltration of pests.  The green vegetable bug, heliothis moth, and monolepta beetle have been encountered by hemp farmers[v].  However, because hemp grows so rapidly, the damage imposed by these pests is minimal and does not appear to affect end yield.  Pesticide use for hemp crops is extremely rare and not a sanctioned practice amongst farmers.

 

How is Hemp Harvested?

The process for harvesting hemp is quite simple, involving a cutting and a drying stage to yield the fibrous stalks that can be used in so many different materials.

 

Cutting

The harvesting process begins with the cutting of hemp plants that have matured at 110 days.  At this point in the plant’s life cycle, it is mature enough to yield desirable stalk, but has not yet undergone the draining, resource-intensive process of pollination.

Hemp is cut down by using a faming combine. This machine cuts the hemp at its base and separates the stalks from grain, seeds, leaves, and any other extraneous material. This is a standard practice used for the harvesting of practically any agricultural crop.

 

Figure 3 - Farming combine and mature hemp stalks

 

 

Retting

Retting is the process of rotting away the softer, less useful parts of the plant by exposure to moist air (dew retting) or submersion in water (water retting).  Water retting is rarely used because it is considered to be environmentally unfriendly since it results in a large amount of dirty water.

 

Dew retting is carried out by leaving recently cut hemp stalks outside for roughly two weeks, depending upon the weather in the region.  During this time, the hemp is naturally decayed by bacteria and other fungal organisms.  The end result is brown-gray hemp stalks that consist of about 15% moisture[vi].

 

For a farm that is planted on 2.47 acres of land, a farmer can expect a yield of anywhere from 6 to 6.8 tons of dried, usable hemp stalks[vii].  This is a tremendous amount of material that can be further refined for many different purposes.

 

How is Hemp Refined?

Hemp can be processed into many different materials after it has been harvested.  We will discuss three popular uses of hemp: in textiles, as paper, and as oil.

 

Textiles

Hemp is strong enough as a fiber to serve as a textile in many different scenarios.  To break hemp down into stringy fibers that are suitable for use in clothing, sheets, etc., the stalks are put through a pressurized steaming process that makes the material more soft and malleable[viii].  The soft hemp can then be cut, woven, and used in the manner of any other textile, such as cotton or wool.

Figure 4 - A necklace made from hemp

 

Paper

Hemp stalks can be crushed into a thick pulp that can be further refined into paper. The pulp is often bleached with hydrogen peroxide, a relatively safe and environmentally-friendly chemical, to yield a brighter piece of paper after production.

 

To create paper from the crushed hemp pulp, the pulp is diluted in a large amount of water.  The hemp/water slush is then poured over a series of tightly-woven wires, leaving only the hemp fibers remaining.  The wet fiber is dried by pressing and steam heating, which results in thin, sturdy sheets of paper suitable for common use[ix].

 

Oil

Hemp stalks can have oil pressed from them for use as ingredients in personal care products like shampoo and soap.   The seeds that are left over from the harvesting process can also have the oil extracted from them for the same purpose.

 

Hemp oil can be interchangeable with the other sorts of oils used in food preparation, such as corn and olive oils.  Foods made from hemp oil are not yet widespread and can usually be found in specialty or organic stores.

 



[i] Seed sowing data represents the maximum number of seeds sown during a particular planting cycle.  Section 9.4 of Information Paper on Industrial Hemp (Industrial Cannabis).

[ii] Information on sunlight gathered from Day Length and Flowering – Hemp.

[iii] Growth duration based on information from The Cultivation of Hemp in the United States.

[iv] Information on resistance to weeds gained from Soils Suited to Hemp.

[v] These types of pests are specifically mentioned in an Australian setting in section 9.6 of Information Paper on Industrial Hemp (Industrial Cannabis).

[vi] Retting information acquired from section 9.9 of Information Paper on Industrial Hemp (Industrial Cannabis).

[vii] Average yield based off of section 8.1 of Information Paper on Industrial Hemp (Industrial Cannabis).  The information was originally in metric and was converted to United States imperial units (acres/tons) by using metric-conversions.com.

[viii] Pressurized steaming can also be called “steam explosion, according to section 3.1 of Information Paper on Industrial Hemp (Industrial Cannabis).

[ix] Information on the pulp to paper process obtained from Hemp Pulp and Paper Production.

Figure 1 was obtained from Cannabinaceae.

Figure 2 obtained from viewing the harvest slideshow at Manitoba Harvest – Hemp Field Tour.

Figure 3 obtained from a series of harvest photos at Hemp Harvest Photos 2006.

Figure 4 obtained from Igitsa, an online vendor that sells hemp-based products.

 

 

Comments (2)

Cameron said

at 9:11 am on Mar 31, 2009

Yours aligns well with the evaluation sheet Doc Staggers provided.

I particularly like the play-by-play at the very end. In my view, I'd like to see that higher in the document, perhaps right after the intro (Wikipedia-style).

Well written, clear. Nice, short sentences, paragraphs.

Nice use of footnoting and labeling of the pictures.

Melissa said

at 9:21 am on Mar 31, 2009

I think this description is well researched and explained a in a clear manner. I also think you might want to take out some of the details regarding how hemp is grown and harvested and spend more time explaining how hemp is refined. Just a thought. I don't believe a conclusion is necessary either. You may want to re-format this a bit and simplify some of the information without discarding the facts.

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