Silk is a very fine filament textile derived from the secretion of an insect called the silkworm.
The silkworm Bombyx best known is the larva of the moth Bombyx mori, that of silk moths, belonging to the order Lepidoptera and the family of Bombicidi.
The complete life cycle of the insect takes about 45-50 days, and through the following stages: hatching, larval growth through age five, spinning the cocoon, butterfly emergence, mating and spawning.
In spring, the eggs hatch when the mulberry tree begins to have leaves in the stage of maturity ideal for feeding newly hatched larvae baby girls, that is, between the end of April and beginning of May.
Hatching seeds whitening and the larvae are born, about 3 mm long.
At hatching the breeder transfers the small silkworms on horizontal trellises covered with mulberry leaves; larvae, about half a centimeter long, are small and dark, after ten days take on a whitish color.
Not all seeds produce the cocoon: on average 10% is lost to the death of the embryo or larva.
The larvae are insatiable and they feed voraciously on the leaves of the white mulberry "Morus alba". To feed 28 grams of seeds are needed 1000 kg of leaves.
The development is huge: the bug increases 40 times in length and 8,000 times by weight.
During development the larva changes four times the skin and any change constitutes a wetsuit. The suits are made about the 5th, 9th, 14th, 21 days after hatching, the larval period and divided into five age.
After about 6 weeks the caterpillar is fully developed and gives start the manufacture of the cocoon: in principle attaches to the branches some sections of burr, constituting the outer casing (spelaìa), then moving the head in all directions running spinning emitting a secretion stringy sticky paste that yes coil to coil.
During this phase, which lasts 3-4 days, the caterpillar ceases feeding and decreases in weight and volume.
Once the cocoon, the caterpillar will "pupates" to become an insect tough, still, dark brown in color, forming the chrysalis. After about two weeks, the chrysalis becomes a butterfly and, thanks to a small gland that emits a special liquid an opening between the filaments that form the cocoon and comes out.
Will mate and give birth to a new life cycle.
The adult moth is usually yellow or yellowish-white, with a stocky body and hairy.
During his short life (10 days) does not feed and die shortly after spawning, yellow, which ensures to a surface by a gummy substance produced by herself.
Usually a moth deposits from 300 to 500 eggs that are fertilized if, shortly after turn brown and hatch within ten days. The seeds are very small, say lenticular shape and brown color. Appropriate institutions collect them, keep them and distribute them to farmers in frames of gauze. 28 grams equals about 55000 seeds and become approximately 70 lbs. Of cocoons.
It is mainly women of rural families to take care of the bug and to follow the various stages of breeding: the mute, the construction of the "forest", the elimination of cocoons putrid, winding wire, freed from sericin manually in 'boiling water using small reels.
Breeding begins putting the seeds of bugs on mattresses. After hatching, the worms are placed on racks wicker, called "silkworm" armor of wood with several shelves made of reed mats.
At this point, the silkworms are covered well and fed with mulberry leaves dry, fresh, clean and crushed.
The first bug that check is called Cavallaro. With the growth of the "knights", increase their appetite and eating mulberry leaves grow rapidly at first then crush them whole.
When the silkworms eat continuously work of peasant family becomes very challenging.
6000 bugs are needed to feed 100 kilograms of mulberry leaves.
This requires that the breeding of silkworms is near mulberry plantations so as to satisfy the greed of the caterpillar leaves always fresh.
The of silk moths this name because his power is made from the leaves of the white mulberry, the most common is the "Morus alba", a tree-like plant native to the Asian regions around the Himalaya.
After about forty days after hatching, four skin changes and an increase in body weight of 10 000 times the original one, worms stop feeding: it is time to spin the cocoon.
The peasant family prepares the "forest" with dry twigs twisted so that bugs can stand on it and make the cocoon clinging to branches. The premises are suitably darkened and the rod, by means of the chain, an organ located below the mouth, begins to spin the cocoon secreting a filament wet which solidifies just in contact with the air.
As soon as the cocoon is completed (about 4 days) is disconnected from the "forest" and worked right away, before it occurs the metamorphosis of the silkworm chrysalis and the inside is transformed into a butterfly escaping and thus breaking the precious filament that for each cocoon is long up to 1000 m. If nothing is done in time, and the little animal is done flicker, once the pupation, the butterfly emits a reddish secretion,
dissolve the gummy substance caking combining the wires and, through the use of a dedicated anatomical file that cuts the fibers, comes out. Within a few days you consume the whole cycle of "silkworm": mating, oviposition and eventually death.
The breeding of silkworms for centuries constituted the fundamental economics of farming families in rural areas of Zhejiang and Jiangsu and the mulberry growing still represents a source of income for these primary.
Reeling and Twisting
In breeding silkworms the reproductive process is interrupted at the stadium since the moth chrysalis, emerging from the cocoon produce lacerations that would reduce the commercial value of the silk and therefore most of the bugs is suppressed.
The cocoons are immersed in boiling water or dried in ovens. Only moths strictly necessary for playback are made flicker.
The recovery of the silk thread is a very delicate process, technically called reeling, and begins with the drying of cocoons followed by a careful selection to classify the regularity and obtain homogeneous yarns.
The cocoons of different types (normal and duplication) are split before starting the task, and then are taken separately, in order to ensure the uniformity of the wire.
The following operations are spelaiatura, scopinatura and reeling.
The cocoon is covered with a fluff, said spelaia. that must be removed in order to unravel the thread after finding the capofilo. For this purpose are used brushes sorghum, which are rubbed with cocoons to highlight the capofilo.
Tied capofilo to a reel, the cocoons are made to rotate in boiling water (to remove the gummy layer that covers) and the filament of four or eight cocoons joined and wound on a reel.
The filament which is obtained is called raw silk and consists normally of 48 individual filaments.
To obtain a semi-consistent four additional steps are necessary: incannaggio, rewinding, doubling and twisting.
The coils are unraveled on a winder that allows the passage of the wires from the coil spool.
The stracannatoio instead moved the wire from a racchetto another, forcing it through a thin slit (clearer), whose task is to clean it from any nodes and eliminate groviglie.
Through Doubling the wires are coupled together so as to prepare the yarn for the subsequent operation of the twisting and make it more consistent.
So through the wringer spools, quickly rotating in the vertical direction, while the reel rotates slowly in a horizontal direction, giving a twist to the filaments.
According to the way it backfires, you will get different types of yarn: the organza, crepe etc.
The first classification is to divide silks taken from those obtained from residues.
In both cases, the other important elements are the fineness and color. The fineness of each bavella ranges from 12 to 15 microns. The colors are the most valued white and yellow, but there are also cocoons green and pink; however much importance is the uniformity of color.
With the silk is important that you get two yarns are the organzine and the plot and have the following characteristics:
The organza is silk yarn of the highest quality and is made from fine silks drawn. It is obtained from two or more wires twisted unique "Z" and subsequently to "S".
Depending on the amount of the wires and the degree of twist you get next organzines: the grenadine or granadine which is the most twisted, the organzine strafilato, the average and the common.
The plot is a yarn obtained with current and thirst, generally used in the plot tissue, crepe stands (the most twisted) and marabout.
The waste can be classified into spelaia, strusa and yarn wastes.
The spelaia includes cocoons sfarfallati used for breeding, those moth-eaten, the incomplete, the bad and the down surface.
The strusa includes cocoons soaked in water during maceration, because they were healthy (gallettame) and the cocoon before the end of the chrysalis (annealed).
The yarn wastes include residues of spinning and twisting.
From the processing of waste combed longer you get a yarn that is called noil silk or Terzanelle or foil; this is the silk yarn commonly used for knitting but because of its nature it can not compete in quality and regularity with silks taken.
Sometimes also the impurities and the small number of nodes present therein influence the result of the finished product. By combing waste, other products come out even more shorts that provide appropriately processed bourette or roccardino.
Mulberry silk: the quality of silk is the most common product of the secretion of two glands moth called "Bombix mori", or more commonly silkworm, which feeds on the leaves of the mulberry tree.
And 'silk most common and the most widespread in sericulture.
Tussah or wild silk: There are other types of silk derived from larvae of various species of moth as "Antheraea Mylitta", "Antheraca proylei", "Antherea pins" and "Antheraca yamamai" living on oak and ash trees, of which they feed, but their cocoon is darker, hard and compact, usually yellow or gray.
The burrs are irregular and of a section coarser. The thirst that derive are called wild (tussah).
The cocoons are brought to a boil in a chemical solution or treated with a softener to obtain a product more fluffy.
Muga: silk native of the production area of Assam and India called "Muga" which indicates Assamese in the amber color of the cocoons.
It belongs to the same family of Tussah and is very popular for its characteristic golden color.
Muga is produced by "Antheraea Assama" and is an endemic species of the Brahmaputra valley.
Eri: other silk of Indian origin. The word comes from the Sanskrit Eri where the castor plant "Ricinus communis" is called eranada.
The leaves of castor, herbaceous plant common in tropical and sub-tropical, belonging to the family Euphorbiaceae, is the diet pricipale of these larvae are called accordingly Eri.
The larvae are the sun You were among those not belonging to varieties that feed on mulberry leaves, in order to be kept in sericulture.
A larva produces up to a maximum of two kilometers of filament, which, however, must be joined with others to obtain a yarn suitable to be used in knitting.
To get a kilo of raw silk are required at least 10 pounds of cocoons, or 6000 silkworms fed a ton of mulberry leaves. In summary, it takes about 1000 silkworms to produce the yarn necessary for the realization of a mesh of 200 grams.