Silk is a natural, lustrous fabric prized for its beauty for thousands of years.
In Roman times, silk fabric was so desirable that traders would bring it from
China to Europe across Asia along a route known as the Silk Road. In Europe
people would attach pieces of silk fabric to their clothes, like jewelry, as it was
more expensive than gold.
Legend has it that around 2640 B.C., Lei Zi, Emperor Huang Di’s wife, walking
in her garden discovered silk when a cocoon fell into her cup of hot tea. As
she idly played with the cocoon, it unwound into a fine thread. That fine thread
was silk and Lei Zi came to known as The Lady of the Silkworm. She is also
credited with discovering the weaving loom.
Silk may have been discovered even earlier in China, as some silk fragments
have been dated to before 3000 B.C. For a long time China was the only
country which produced silk fabrics. China kept secret the technique of making
silk for centuries. Anyone caught trying to smuggle the secret out of China was
severely punished or even executed.
Chinese immigrants are said to have brought silk worms to Korea around 200
BC. And, around 550 AD, two Nestorian monks brought silkworm eggs to the
court of Emperor Justinian in Rome by hiding them in their hollowed staffs.
At the bottom of all this intrigue and beauty is a small moth of the Lepidoptera
order belonging to the Bombycidae family. One species of this moth, the
Bombyx Mori, is responsible for the vast majority of the silk currently produced
and is cultivated under controlled conditions in silk farms or factories. This
blind, flightless moth lays about 500 tiny eggs at a time.
Once hatched, the Bombyx Mori worms are placed on a bed of mulberry
leaves and each worm devours about 30,000 times its weight and grows from
about a quarter an inch to about 3 inches in 30 to 45 days. The mature worm
then spins its cocoon. The cocoon is made up of one continuous strand of silk
filament 700 to 1000 yards long. The filament, spit out from two spores on top
of the worm’s head, is coated with sericin, a glue-like substance to hold the
threads together to form a cocoon.
The process of cultivating the silkworms to produce silk is called sericulture,
from serica, the Greek word for silk
There are also undomesticated silk worms, like the tussah, which are found in
the wild and come mostly from India. The color and quality of silk from these
worms, called raw silk, depends on what they feed on. Normally, the silk from
these worms are more yellow and less strong.
Except for a few kept aside for the next generation of Bombyx Mori, the rest of
the cocoons, once mature, are heated and then the cocoon can be stored.
To start production, the cocoon is moistened to loosen the filament. The
filament is thinner than hair but very strong. Any fabric woven with a single
strand of silk filament will be very sheer and see-through. Usually, five to eight
filaments of silk yarn are reeled together on a spool to increase the thickness
of the strand.
Several strands of silk are then twisted together, in a process called throwing,
to make yarn for weaving. The gummy substance, sericin, is then removed by
boiling the silk in soap and water, leaving it soft and lustrous. The sericin may
also be removed after the fabric is woven. In India, they beat woven raw silk
with sticks to remove serinin and make the silk soft.
The yarn is then twisted and separated into warp and weft yarns and rolled
into hanks. The warp yarn has more twists than the weft yarn as it needs to be
stronger. The yarn is ready to be bleached and/or dyed and made ready for
weaving.
Initially woven on handlooms, the silk yarn is strong enough to be woven on
the latest shuttle-less looms.
Silk is by far the strongest of all natural fibers and has excellent elasticity and
resilience. It is also very light, soft and smooth and takes dyes extremely well.
Silk resists mildew and damage by moths. It is non-flammable, though not fire-
retardant.
Silk can absorb moisture but loses some of its strength. Therefore, it is best
dry-cleaned.
All these qualities make it a highly desired fabric for elegant dresses and home
décor.