Hemp Hurds as Paper-Making MaterialDewey, Lyster H. (Lyster Hoxie)
Science
Hemp Hurds as Paper-Making Material
Dewey, Lyster H. (Lyster Hoxie)
Fiber plants; Hemp; Paper industry
The hemp stalk grown in a broadcast crop for fiber production is from
one-eighth to three-eighths of an inch in diameter and from 4 to 10 feet
tall. The stalk is hollow, with a cylindrical woody shell, thick near
the base, where the stalk is nearly solid, and thinner above, where the
hollow is relatively wider.
In the process of breaking, the woody cylinder inside of the
fiber-bearing bark is broken into pieces one-half of an inch to 3 inches
long and usually split into numerous segments. The thicker lower
sections are split less than the thin-shelled upper ones, and they are
often left quite solid.
=PITH, WOOD, AND FIBER.=
The inner surface of the hurds usually bears a layer of pith, consisting
of thin-walled cells nearly spherical or angular, but not elongated.
They are more or less crushed and torn. They are probably of little
value for paper, but they constitute less than 1 per cent of the weight
of the hurds. The principal weight and bulk consist of slender elongated
woody cells. The outer surface is covered with fine secondary fibers
composed of slender elongated cells, tougher than those of the wood but
finer and shorter than those of the hemp fiber of commerce. No method
has been devised thus far which completely separates from the hurds all
of the long fiber. From 5 to 15 per cent of the weight of the hurds
consists of hemp fiber, in strands from 3 inches to 8 feet in length.
Some fragments of the bark, made up of short cubical cells, usually dark
in color, cling to the strands of fiber.
=CHARACTER OF HURDS AFFECTED BY RETTING.=
Nearly all of the hemp in the United States is dew retted. The stalks
are spread on the ground in swaths as grain is laid by the cradle. The
action of the weather, dew, and rain, aided by bacteria, dissolves and
washes out the green coloring matter (chlorophyll) and most of the gums,
leaving only the fibrous bark and the wood. The plants in this process
lose about 60 per cent of their green weight, or about 40 per cent of
their air-dry weight.
The stalks are sometimes set up in shocks to cure before retting, and
after retting they are set up in shocks to dry. Each time the stalks are
handled they are chucked down on the ground to keep the butts even. In
these operations sand and clay are often driven up into the hollow at
the base of the stalks, and this dirt, which often clings tenaciously,
may constitute all objectionable feature in the use of hemp hurds for
paper stock.
In Italy and in most localities in Russia and Austria-Hungary where hemp
is extensively cultivated, it is retted in water, but water retting has
never been practiced in the United States except to a limited extent
before the middle of the last century. Hurds from water-retted hemp are
cleaner and softer than those from dew-retted hemp.
Public-domain text, read in full here on John Shaqi.
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