Fibers
Plant and animal fibers have
provided humans with, among other things, shelter, vessels in which to hold water
and cook food, and thread for making fabrics.
Even tho most of the world
has abandoned mud and waddle home construction and baskets smeared with clay as
water vessels or cooking utensils, plant fibers as a source of weaving still
remains current in use.
In prehistoric times humans
probably obtained flexible plant fibers simply by pulling off strips of bark or
cutting stems and leaves onto thin, weavable ribbons.
Altho these materials can be lashed and interlaced into
mats and baskets, they produce only coarse, stiff items.
Major innovation was
the discovery that individual fibers could be separated from surrounding cells
and used to weave textiles.
Animal skins probably
predated woven material, but plant fibers probably predated animal fibers for
woven material.
* Sandals, made of complex woven plant fibers, over 8,000
yrs old, have been found at an archaeological site in
* By 5400 years ago, native people of
* Linen was woven 10,000 years ago in
These dates are fairly recent
when you consider that the association of the genus Homo with plants and
animals dates back hundreds of thousands of years. The recency is
understandable when you consider that:
Only
a small number of animals (sheep, camels, vicunas, guanacos, goats, rabbits,
and the silk moth) and relatively few plants produce fibers that can be twisted
or spun.
Humans
had to appreciate the nature of fibers, learn which plants contained them, and
learn how to extract them before spinning and weaving them.
Fibers
1.
With the
exception of synthetic polymers, most economically important products, such as
cordage, paper, textiles, are derived from plant fibers.
2.
Fibers are
elongate cells with tapering ends, and very thick, heavily lignified cell
walls.
3.
Fiber cells are
dead at maturity and function as support tissue in plant stems and roots.
4.
The lumen, or
cavity inside mature, dead fiber cells, is very small in cross section.
5.
Fibers are one of
the components of sclerenchyma tissue, along with shorter, thick-walled sclereids
(stone cells) which produce the hard tissue of peach pits and the gritty
texture in pears.
6.
Fibers are also
associated with the xylem and phloem tissue of monocot and dicot stems and
roots, but generally not the wood of gymnosperms (softwoods).
a.
The primary
reason why gymnosperm woods are generally softer and lighter than angiosperm
woods is the presence in angiosperm wood of dense clusters of
heavily-lignified, thick-walled fiber cells.
b.
The fiber cells
increase the hardness and density of angiosperm wood.
Vegetable fibers Animal
fibers
|
Composed of cellulose |
Composed of protein |
|
Not subject to denaturation
by high temperatures. Cotton sheets can be boiled when washed. |
Heat cracks protein
backbone of animal fiber making it brittle. Woolen garments ruined by hot
water. |
|
Requires elaborate
treatments to ensure successful color adherence |
Accepts dye readily |
|
Immune to animal pests but,
like paper, attacked by fungi, mold, and termites. |
Susceptible to attack by
animal pests, such as moths and silverfish. |
|
Less elastic than animal
fibers. |
More elastic than vegetable
fibers. |
|
High affinity for water:
more absorbent. |
Low affinity for water: not
absorbent. |
The
fundamental chemical difference, between cellulose and protein, determines how
the 2 types react to heat, various chemicals, water, and predatory organisms.
With the exception of synthetic
polymers, most economically important products, such as paper, cordage (cords
and ropes) and textiles, are derived from plant fibers.
Properties of textile fibers
1.
Fibers can be spun if they have structural properties that cause individual strands to
clasp one another when twisted.
a.
Most animal hairs cannot be spun
because they are too slippery to stay together when twisted around one another.
2.
Elastic
properties are a measure of the facility with which a fiber can regain its
original shape after it has been stretched.
a.
The amount a fiber has been twisted, the way in which the cells are held
together, and the number of cells per fiber contribute to its elasticity.
3.
Fibers have
different densities of weight relative to an equal volume of water, which
affects how fibers made from them will drape.
4. Fibers high
in cellulose are considered valuable because cellulose is extremely strong with
properties of tensile strength rivaling that of steel.
5. Fibers high
in lignin are generally of poorer quality, browner in color, with lower
mechanical strength.
Kinds of fibers
1.
Bast fibers
– comes from phloem tissues in the stems of various dicotyledons (linen from
the flax plant)
2.
Hard fibers
– come from the leaves of a few monocotyledonous plants century plant, Manilla
hemp).
3.
Surface fibers –
found on the covering of seeds, leaves, or fruits; cotton cloth is made from
seed hairs covering the surface of cotton seeds
Fiber Extraction
Despite
the fact that various fibers come from many different and unrelated plants, the
same basic procedures are used to separate the fibers from the masses of cells
in which they are embedded. The primary processes are: retting, scotching,
decorticating, and ginning.
Separating fibers from masses of other
cells in which they are embedded.
1.
Retting
(bacterial rotting).
a.
Extraction
process that rots away the soft plant parts and leaves fibers intact.
b.
Used mainly for
bast fibers (phloem tissues of dicots) and takes advantage of the fact that fibers
have thicker cell walls than do most other plant cells, and are therefore
comparatively resistant to breakdown by bacteria.
c.
Plant material
can be retted by dumping the mass into tanks of stagnant water, or simply allowing
it to remain on the ground where it will be repeatedly covered with dew.
d.
During retting,
tissues absorb water and swell, causing release of soluble compounds that help
provide nourishment for decomposing bacteria.
e.
Retting takes a
few weeks.
1.
The mass of
rotting material must occasionally be tested to ascertain the point at which
soft tissues, but not fibers, have disintegrated.
f.
There may be
epidermal and thick-walled woody xylem cells that can persist.
1.
These are removed
by washing and drying the material after retting.
2.
They are then
"broken" by means of being forced under fluted rollers.
3.
the rollers
crumbles the brittle material, but not the more flexible bast or leaf fibers.
4.
Broken pieces are
then removed from fibers by the process of beating and scraping, called scutching.
5.
Finally, fibers
are drawn down across a set of vertical pins resembling a comb, called hackling.
Decorticating - entails crushing plant material and scraping
nonfibrous material from fibers. Used primarily for leaf fibers.
Ginning - unique to seed fibers. Seeds are pulled free from
the fibers covering them.
Once
extracted and cleaned, fibers can be further processed by bleaching or heating,
or both, in an alkali solution. Fibers are usually bleached before dying so
their natural tans and brown pigments don't effect the final color.
Seed and fruit fibers
1.
Although seed and
fruit fibers come from different parts of the fruit, both aid in seed
dispersal, but by different mechanisms.
a.
Long fibers on
seed surfaces promote dispersal by wind. (e.g. tufts of hair on top of
milkweed, Asclepias spp.).
b.
Fibers within
fruit wall generally protect seed or provide buoyancy for water dispersal, or
both (coconut).
2.
Few plants have
seed or fruit fibers long enough for spinning. Cotton is the notable exception
because it produces seed fibers that can be spun into thread.
a. Seed fibers from milkweed and kapok (Ceiba pentandra, Bombacaceae) are too
fine and slippery to spin. These are used primarily as stuffing material and
kapok was formerly used for life preserves because it’s lightweight and water
resistant and has fibers that trap air.
1.
Kapok hairs
are produced on the inner surface of the seed capsule of the kapok tree, in
tropical regions of the
2.
It's an enormous
rainforest tree with a massive buttressed trunk.
3.
Hairs are coated
with a highly water-resistant, waxy cutin.
4.
The empty lumen
is larger than cotton hairs and hence the fiber is lighter in weight.
5.
A kapok-filled
life jacket can support 30 times its own weight in sea water.
6.
Milkweed hairs
were used as a substitute for kapok during WWII.
7.
The hairs can
also be twisted into dental floss.
b. Coconuts are unique because they produce the only fruits from
which fibers (coir) are extracted
from the pericarp for commercial use.
Coir
1.
Bulk of mature
coconut consists of thick, fibrous mesocarp that constitutes source of a fiber
called coir.
a.
Coir fibers are
made up of bundles of cells that are longer than cotton fibers but shorter than
most bast or leaf fibers.
b.
High-grade coir
produced by harvesting and husking 10-month old (immature) coconuts.
1.
Husks are retted
for 8-10 months in brackish water.
2.
When soft, husks
are thoroughly washed, beaten to remove pulpy remains, shaken, and washed
again.
3.
Clean fibers are
spun into yarns primarily used for ropes and matting.
c.
That the most
valuable coir fibers come from unripe coconuts presents an economic problem because the most valuable commodity obtained from
coconuts is copra, the dried coconut
endosperm, which is eaten or used for oil.
1. Copra can be obtained only from mature fruits.
2. Consequently, although mature fruits yield fibers that
are tougher than those of young coconuts, most coir is extracted from old husks
that remain after the copra has been removed from ripe fruits.
3. Cotton
a.
Most important
fiber today; most important nonfood plant commodity.
b.
Large amount of
fiber produced by each plant combined with the fact that picking, processing,
and manufacturing of textiles from cotton cost less than processing other
fibers.
c.
Versatile fiber
that produces textiles that dye well, and withstands rigorous washing.
d. Each cotton
fiber is a single long epidermal seed coat cell. Unicellular
hairs that grow out of the surface of the seed after fertilization.
1.
Cells are so long
they resemble hairs.
2.
The hairs are
twisted into usable thread which is tough and strong.
3.
In cultivated
cotton, there is a second layer of short fuzzy hairs underneath the long
fibrous hairs. These short hairs, or linters, are removed and used in paper
making when cottonseed is used as an oilseed crop.
4.
Cotton thread is
spun from billions of microscopic hairs covering the surface of cotton seeds,
each hair up to 50 mm (2”) long. The total length of hairs in a single cotton
boll (one seed capsule) may exceed 300 miles. (How many miles from a standard
500 lb bale?)
e.
Gossypium arboreum and G. herbaceum (
1. Both have short fibers, or staples, and both were
eventually replaced by
2. G. hirsutum and G.
barbadense are new World tetraploids.
a.
Archeological
excavations date to 3,400 BCE in
b.
G. hirsutum
comprises 95% of the world's supply of cotton.
c.
G. hirsutum
is relatively resistant to boll weevil.
d.
Cotton hairs
(lint) of the tetraploid species may be up to 50 mm (2") long.
e. Most species
of cotton are tropical perennials, but in cultivated species, humans have selected for an annual habit and the
ability to bloom and fruit in temperate lattitudes.
1.
Growing cotton as
an annual is advantageous for farmers because it ensures a short stature,
uniformity of plant size, and synchronous fruiting.
2.
On modern farms,
plants are often sprayed with a defoliant when cotton is mature so that the
foliage will not interfere with harvesting machines that pluck mature bolls
from plants.
3.
Once picked,
seeds with their fibers must be removed from the fruits; fibers are then
separated from the seeds.
4.
Most Americans
know that Eli Whitney invented the cotton gin, a machine that pulls cottonseeds
from the fibers, in 1794, but the importance of this equipment may not be
widely appreciated.
i.
In 1791, three
years before Whitney’s invention, the
ii.
By 1800, exports
had jumped to 30, 000 bales.
f.
Sizing –
consists of the addition of a thick substance, such as starch or a gel, on the
surface to stiffen (firm) it and fill surface irregularities. Cotton is usually
sized with starch or resin.
1.
important for
threads that will be used for the warp (major loom threads).
2.
sizing material
washed out after weaving is done.
3.
increase strength
of thread
g. Cotton
fabrics used to shrink
1.
There was the
tradition of buying a cotton garment 1 size too large in anticipation of
shrinkage due to initial washing.
2.
Sanforization
(1970) is an ammonia process that swells cotton fiber and prevents their
shrinkage after washing.
h.
Cotton fabric has a tendency to wrinkle when washed.
1.
Permanent press
- chemicals are used to cross-link the cellulose polymers of cotton cloth
causing the fabric to retain shape it had when chemicals were first applied.
2.
This process also
keeps surfaces smooth and allows pleated or ruffled garments to retain shape
after washing.
Bast fibers from the bark of stems (soft fibers)
1.
Thick-walled
fiber cells occurring in the phloem parenchyma of stems of various dicots.
2.
Bast fibers
constitute the main source of stem fibers.
3.
Individual bast
fibers can be made up of hundreds of cells and can be over 4.6 m (15') long.
4.
Fibers usually
separated from stems by retting.
Jute (Corchorus capsularis)
Tiliaceae - world's foremost bast fiber
1.
Jute has been
used since prehistoric times.
2.
Probably yielded
fibers for some of the sackcloth referred to in the Bible.
3.
Herbaceous
annual, up to 5 m tall; yields fibers 1.8 - 3 m (6-10') long.
4.
Fibers are
relatively inelastic, and tend to disintegrate rapidly in water.
5.
Fibers are
separated from the stems by deep-water retting.
6.
Their roughness,
brittleness of fibers, and inability to hold dyes promote use of jute fibers
for coarse goods such as carpet backing, canvas, twine, "gunny
sacks", burlap, etc.
7.
Popularity of
jute is primarily due to its low cost, which results from its raid growth and
the ease with which its fibers can be extracted from the stem.
Flax (Linen) Linum usitatissimum.
Linaceae.
1.
Oldest textile
fiber used by humans.
a.
Archaeological
digs uncovered remains of flax species in ancient settlements occupied by
b.
Egyptian mummies
dated about 5,000 years ago were generally wrapped in linen cloth.
c.
Carvings on
Egyptian tombs document its cultivation along with wheat, figs, and olives.
2.
Etymology -
the words 'line' (as in straight lines) and lingerie and the generic name,
Linum, are derived from the Latin word for linen.
3.
Flax is native to
4.
The plants from
which fibers are obtained are tall, little-branched, annuals that yield oil as
well as fiber.
5.
Flax fibers are
smooth, long, straight, and 2-3 times stronger than cotton fibers. They are
used for making buttonholes and button thread, as well as for hoses and
mailbags.
6.
Flax is generally
obtained by dew retting the cut stalks of mature plants.
a.
This takes about
3 weeks.
b.
Plants are now
sometimes uprooted and chemically retted (chemicals dissolve the matrix between
cells before retting begins).
c.
Because of hand
labor involved in traditional flax fiber extraction, linen has always been a
relatively expensive textile.
7.
Linen textiles
are generally soft, lustrous, and water-absorbent,
and linen is also used for towels.
8.
Linum is also the
source of linseed oil, an unsaturated drying oil used in the original linoleum
and in the paint industry. Linoleum = linum (flax) + oleum (oil).
Hemp (Cannabis sativa)
Cannabaceae.
1.
Cannabis
initially spread around the world because of its fiber, not because of its
resinous compounds (THC).
2.
Native to western
a.
Seeds were
consumed along with millet, rice, barley, and soybeans in ancient
3.
Dioecious, annual
herbs.
4.
Hemp fibers are
the longest of any bast species, ranging from 1.5 - 4.5" (5-15') in
length.
a.
Staminate plants
produce the best and longest fibers, up to 2 meters long.
b. They were used to weave the cloth of which most
Chinese garments were made in ancient times.
c.
The yarn woven
from these fibers were exceedingly fine, so much so that people were buried in
hemp garments.
5. Hemp produces dark, rough fiber and as a result is
typically used for cordage, rope, canvas (the word derives from Cannabis), covered wagons, and sailcloth.
6. Etymology: Levi Strauss originally made work clothes of hemp;
it was imported from Mines,
7. Altho cultivation of hemp has been illegal in the
8. Hemp was once extensively planted throughout the
9. Grass root movement to legalize the production of
industrial hemp. Supporters for legalization point out the low THC content in
the hemp plant.
10.
Requires no
irrigation or pesticide use: cotton requires considerable amounts of both.
11.
Navajo Nation
now considering hemp production on their lands.
12.
The Chinese
harvest many tons of hemp fiber annually to produce fiber for paper, rope, and
cloth.
13.
Another hemp
plant, Apocynum cannabinum, (Indian
hemp), was an important fiber plant of native North American people, and is native
to certain areas in
Leaf Fibers (Hard fibers)
1.
Most leaf fibers
are obtained from rapidly growing monocots with fibers that can be easily and
inexpensively extracted by decorticating machines.
2.
The fibrous
strands occur within the phloem in the vascular bundles scattered in leaves and
leaf bases.
3.
Within the
leaves, the thick-walled fiber cells provide support.
4.
Once extracted,
the fibers can be spun, but they are too stiff to be made into textiles
suitable for modern clothing.
5.
The name 'hard' refers
to its stiffness.
6.
Hard fibers tend
to be shorter than bast fibers.
7.
Leaf fibers,
however, make better ropes than do bast fibers.
8.
Although other
plants are generally used, two genera, Agave and Musa, supply
virtually all the commercially important leaf fibers.
A.
Sisal
1.
Sisal comes from
the leaves of Agave sisalana, native
to
2.
In addition to
fibers, A. sislana has sharp spines
on the ends of its leaves that have been used by native peoples as needles.
3.
Combination of
fiber and sewing utensil gave rise to the common name, "needle and thread
plant".
4.
Today the fibers
are used for sacking, mats, and tea bags and as reinforcements for materials
such as rubber.
5.
The sap tapped
from this agave can also be fermented into a mildly alcoholic wine known as
pulque.
6.
Fiber removal
a.
Outer mature
leaves are cut at the base, carted to factory, and fed between rollers that
squeeze out most of the water and turn the soft tissues into an amorphous mush
that is scraped away from the fibers.
b.
Fibers are then
washed and hung in the sun to dry.
7. The sun-dried leaves of Yucca elata are used extensively for the
main visible white coils in baskets of native North American people, including
the Papago, Pima, and Havasupai.
B.
Abaca (Manila hemp)
1.
Manila hemp comes
from Musa textilis (Musaceae), a
relative of the banana, native to the
2.
Fibers are
extracted from the outer parts of the leaf bases that make up the
"stem" of these giant herbaceous plants.
3.
Most people have
come into contact with products using Manila hemp in the form of tea bags,
dollar bills, "
4.
They make the
finest ropes, which have held ships to docks throughout the world. Manila hemp
rope is being replaced with nylon in many parts of the world.