The royal fibers, silk have a long history and legends around its manufacture. the process of silk worm rearing, properties and uses of the fiber are discussed in this ppt

1. Fiber to Fabric
Dr. Ritu Madhan

2. The possibility of
making cloth from
the filament that the
silkworm spins into a
cocoon was first
discovered in China
about 2600 B.C.
A legend tells us that
a Chinese princess
was having a cup of
tea in her garden
when a cocoon
accidentally dropped
in her cup of tea.
The hot liquid
softened and
loosened the fiber
which the princess
pulled and drew
away from the
cocoon as a
continuous strand.
Another story cites
Empress Si-Ling-Chi
as the first producer
of silk fiber, from
which she made a
silk robe for her
husband.
From antiquity to the
more recent
establishment of the
Chinese Republic,
she was validated as
the goddess of the
silkworm.
This was the
beginning of the new
industry the orient
which finished the
livelihood for
millions of workers.

3. The Chinese who
first cultivated
the silkworm and
developed the silk
industry
endeavored to
keep the source
of the raw
material secret.
The silk fabrics
were highly
prized.
Caravans carried
silk into the near
east where they
were traded for
100s of years.
About 3000 years
after its original
discoveries the
secret was stolen
out of China.
Attempts have
been made to
cultivate the
silkworm in the
US, but they have
not succeeded
commercially
because of high
labour and
production cost.

4. Egg
Larva /
Caterpillar
Pupa /
Chrysalis
Moth
Cultivation
of silk is
called
Sericulture

5. Begins when silk worm lays eggs
When eggs hatch, caterpillars (larvae)
are fed fresh, young mulberry leaves
After about 36 days & 4 moltings,
silkworms are roughly 10,000 times
heavier than when hatched—ready to
begin spinning a cocoon
A straw frame is placed on a tray &
silkworm spins cocoon by moving its
head in a figure eight

6. Silkworm secretes liquid
through spinneret (small
opening under the Jaw)
This is a protein secretion
which is in the form a
double strand of fibroin,
held together by a gummy
substance called serecin,
or silk gum.
In 2-3 days the silkworm
will spin approximately 1
mile of filament and
completely encase itself
Silkworm then
metamorphoses into a
moth—usually killed
before reaching moth
stage-Stoving/Stifling

7. Silk
from
cocoons
Thrown silk
Reeled silk is transformed
into silk yarn also called as
thrown silk
It does not include the
process of carding, combing
and drawing
Spun silk
Short lengths of inferior
quality silk filaments
obtained from waste
material are not used in
producing reeled silk

8. Sorting
Color, shape,
size and
texture
Softening
the Sericin
Hot and cold
immersions,
unwinding the
filament
Reeling the
filament
The ends of
filaments are
combined
together into
skeins and
packed in
small bundles
called books.
Silk delivered to the factory is called filature

9. Several filaments
combined to form a
yarn
Operators must
carefully join filaments
so diameter of reeled
silk remains uniform in
size—uniformly reeled
filament silk is most
valuable
Twist can be added—throwing—thrown yarn
Single yarn — simplest, 3-8 filaments twisted
together

10. Silk
Mulberry silk
Wild silk
Eri
Muga
Tussar
Duppion

11. Mulberry silk is made by the
silk worm of the Bombicide
variety. There are two types:
Univoltine and Multvoltine.
Univoltine – 1 time in a year
Multivoltine – 6-8 times a
year
The cocoons of the
univoltine silkworms
(Bombyx mori) are of a firm
and close consistency, so
that the silk can be readily
reeled from them.
The eggs require a certain
degree of cold to hatch. The
eggs of multivoltines (Bengal
silk worm) hatch out
healthily without exposure
to cold and their cocoon
contain small amount of silk.
The worms are cultivated
and fed on mulberry leaves.

12. Tassar Silk:
It is obtained from an
oak-feeding moth,
native of India and
china.
Indian tassar is sought
in Europe and USA for
men’s suiting and
other dress material
and for use as
tapestry and
upholstery material.
Muga Silk:
It is to some extent
domesticated in India.
It is a native of Assam
and has better gloss
and other qualities
This silk is of a rare
golden yellow in
colour.
Eri Silk:
It is a native of Bengal
and Assam. The Eri
worm feeds itself on
castor leaf.
The cocoons are
remarkable soft,
white or yellowish
and the filament is
exceeding delicate

13. It is a type of wild /
cultivated silk;
It results from two silkworms
spinning cocoons together
The fibers are irregular in
diameter, thick-and-thin
appearance

14. Silk is only natural filament
fiber
Solid fiber, smooth but
irregular in diameter
Filaments are triangular in
cross section, with rounded
corners
Fibers are very fine, wild silks
slightly coarser. Fiber has
slight striations along its
length

15. Protein in silk is fibroin—15 amino acids in polypeptide
chains
It has no cross linkages and no bulky side chains
Molecular chains are not coiled, as in wool, but are
pleated and packed closely together
High orientation contributes to its strength
Elasticity due to some amorphous areas between
crystalline areas

16. •Only natural filament fiber
Length
•Very fine of 9-11 microns
Diameter
•Raw mulberry(off white to cream color)
Tussar(tan to light brown), Muga (golden yellow)
Color
• Soft luster (triangular cross section and smooth
surface)Wild silk has dull luster due to irregular
surface
Luster
• Strong natural fiber. Wet strength is 80-85% of
dry strength
Tenacity

17. Elasticity
&
Elongation
Moderate
elongation
and good
elastic
recovery
Resiliency
Medium
resiliency
less than
wool but
better than
cotton.
Moisture
regain
11%
moisture
regain,
quite
absorbent
and
comfortable
to wear
Drapability
Excellent
Drapability
due its
properties
of pliability,
suppleness
elasticity
and
resiliency.

18. •Concentrated mineral acids dissolve silk faster than wool.
•Organic acids do not harm silk.
•Acetic acid is used to impart scroop or rustling sound
Acids:
•Can be damaged if the concentration and temperatures are high.
•Neutral soaps and luke warm water should be used for laundering.
Alkalies:
•Chlorine bleaches are harmful to silk.
Bleach:
•High affinity to dye
Affinity to dyes:
•Damaged by perspiration.
Perspiration:

19. Thermal
conductivity:
• Nonconductor
of heat
• Lower thermal
conductivity
than cotton
• Excellent fabric
for winters
• Weighted silks
are better
conductors of
heat
Effect of heat:
• Starts to
decompose at
165oC
• Burns with
sputtering, is
self
extinguishing,
emits an odor
of burnt hair
and leaves
residue of
brittle black
bead
Effect of
sunlight: it is
weakened by
long exposure to
sunlight, faster
than cotton or
wool. Raw silk is
more resistant
than degummed
silk. Weighted
silk is least
resistant.

20. Damaged by
carpet beetles
Fairly resistant
to moths,
mildew, bacteria
and fungi