Saturday, July 15, 2006
THE SUBSTANCE OF HEMP STALKS
A 1747 observation of the hemp stalk reads:
The stalks of Hemp are hollow within, or only filled with a soft pith. This pith is surrounded by a tender, brittle, woody substance, which is called the reed: over this reed we find a thin bark or rind, composed of fibres extending in a parallel direction along the stalk: this bark adheres pretty strongly to the reed; and the longitudinal fibres of which it is composed, are joined together by a vesicular or cellular web; the whole being covered by a very thin membrane, which Botanists call the epidermis.
As Lyster Dewey was to note in 1913, this was commercially the most important part of the plant; thus an understanding of it is crucial. Chemically, it is mainly cellulose, which is the most common organic compound. The second most common organic compound is lignin, which is also found in hemp. It is the cellulose which is by far the more useful of the two from the perspective of the hemp world. From it we obtain paper, textiles, insulation and a basic molecule which can be converted into ethanol and other compounds, including a number of plastics.
The stem has a bark from which the fibres are obtained, comprising roughly 25% of the stem, whilst the inner core, or hurd, makes up the remaining 75%. The outer part is higher in cellulose, with the hurd containing from 30-65% cellulose. It is thought that the cellulose content increases with age.
The hemp plant grows from 3-25 feet, though generally a 10 foot stalk is considered good. An acre can produce up to 10 tons of stem, easily giving 3-4 tons of cellulose.
[for related posts on this, use word search feature at top of blog; key words: pectin, lignin, cellulose, stem, stalk, fibre, textile, retting]