A thread produced by the silkworm caterpillar. How silk is obtained: a fascinating excursion into history
I recently bought silk scarves for my collection, made by Uzbek craftsmen using the ancient ICAT technique. The technique is incredibly labor-intensive, because it is manual... everything is done by hand, starting from cutting mulberry branches to feed the silkworm caterpillars...
The photo of watermelons is not related to silkworms, but it is relevant to the further discussion. All photos have captions if something is not clear.
Woman selling watermelons at the bazaar in Andijan, Uzbekistan
But at the beginning of the conversation I will show you my purchases. It’s not that I’m bragging... now such things are available for purchase via the Internet and cost quite reasonable money, considering the labor-intensive processes - so almost for nothing, I think. Rather, I admire these products and it’s a pleasure to simply own them. I am glad that I have them, like small grains of the world of my childhood, particles of my Motherland... I wrote earlier that I was born in Central Asia and from birth I saw this colorful world. We went to the market, and there they sold fabrics, and there were mountains of watermelons and melons, spices, ripe tomatoes, and apples and cherries grew on the trees just like that... A strange world...
This is how they sell onions at the bazaar in Fergana, and throughout Central Asia
So, shopping. Two scarves, blue-yellow and red-green. , length about 170 cm, width 49 cm. Scarves are so narrow because they are woven by hand on narrow looms. In Uzbekistan, it is customary that all ikat (fabric made using the ICAT technique, also called “Uzbek pattern”, pictured below) are woven narrow, because this width is convenient for handwork.
Silk scarf ikat shoyi, Uzbekistan
Second
My silk scarf ikat shoyi, Uzbekistan
My silk scarf ikat shoyi, Uzbekistan
These scarves are made from 100% natural silk. This can be checked in this way: set fire to a small piece of material, it is enough to set fire to even 1 thread, which is what I did.
Natural silk, when burned, quickly forms a black lump, and this lump smells like burnt horn or feather (which is chemically the same thing, keratin), which easily rubs in your hands (see photo) into dust.
The unnatural material will melt and there will be a lump at the end of the burnt thread…. how to put it more precisely... like lava, such a clot... and it does not rub into dust with your fingers. Viscose, when burned, smells like burnt paper (paper, in fact, it is, since it is made from cellulose), and polyester, which is generally synthetic, will melt and burn without a residue.
Two scarves, blue-yellow and red-green... the threads are dyed with natural dyes, but I will talk about the ikat production technology in the next article, and now a little about silk production in general.
Silk is chemically a protein (protein), so they are called: “silk proteins” and are a long-long chain polymer, more precisely, a “bundle” of these polymers. This polymer (which is silk) is produced internally (like a microfactory!) and released from itself by the silkworm caterpillar at a certain age. These silkworms were domesticated in China 5,000 years ago, but what does "domesticated" mean? In this case, this means that they are selected to obtain a better product, mated with the right person (although females can lay eggs without mating) to increase the size of the cocoon and the thickness and length of the thread in it, its growth rate and efficiency ( cocoon) digestion, their (caterpillars) resistance to disease. In the same way, tolerance for human presence and living “on top of each other” was changed (see photo below, this does not happen in nature). All these modifications have made the domestic silkworm completely dependent on humans... for its survival
Silkworm breeding in Thailand, final stage, cocoons before boiling
The silkworm, like the Drosophila fly, reproduces and grows quickly, so it is easy to track various gene modifications on it. I read the following phrase: “The silkworm is one of the most genetically exploited animals.” Over the 5000 years of domesticated existence, the silk productivity of silkworm varieties has increased almost tenfold relative to its wild ancestors (only corn is ahead of the silkworm in this parameter...). Scientists are also trying to genetically influence the duration of various stages of life of silkworm larvae and caterpillars, and health, productivity, quality of silk, resistance to various pathogens... a lot of different things depend on them, in turn.
Silkworm cocoons at a silk factory. Looks like it's China.I will briefly describe the process of obtaining silk.
In the summer, silkworm butterflies (after mating with a male silkworm) lay eggs: these eggs are called "grena". This grain is placed in the refrigerator until spring, that is, until the new season. The next spring, with a gradual artificial increase in temperature from 18 to 25 degrees and a certain humidity, the grena awakens, it is checked for the presence of diseased and defective (I don’t know how they do this, apparently by the color of the masonry... something came to mind), then from grenas hatch into 2 mm worms (silkworm larvae). These worms eat crushed mulberry leaves day and night, devour them and grow, devour and grow (and within a month increase in size up to 3-4 cm)... This time of growth and weight gain is quite difficult for the maintenance staff of the greenage factory (so are called factories where silkworm caterpillars are raised from their eggs. Such a factory was in the city of Osh, where I was born): the caterpillars are in large trays with mulberry leaves and are very sensitive to sounds, smells, temperature changes, humidity, pressure (these are not caterpillars). simple, but domesticated in ancient times and varietal, highly productive, not the same as in simple nature. Well, like a wild orange and a cultivated one... I wrote about this above).
pallets with silkworm caterpillars and crushed mulberry leaves
If you don’t follow the rules, the caterpillar will simply die and all your work will be in vain...
Silkworm caterpillars molt 4 times during growth (they also grow and their skin becomes small for them), while their appetite grows almost exponentially.. The color and appearance of the caterpillars changes greatly from molt to molt, in the bottom photo these are white caterpillars with a horn, judging by the description, are in the 5th instar stage (shortly before pupation).
There are so many caterpillars and they eat the leaves so loudly that you can hear it... And then the time comes for metamorphosis into a pupa... the skin of the caterpillars becomes stronger and yellower and silkworm breeders transfer these caterpillars to special branches or nets (like the one in the photo), to which the caterpillars attach and begin to form a silk cocoon.
Formed silkworm cocoons
To form a cocoon, the caterpillars begin to secrete a certain substance from special glands that hardens in air. This substance is a mixture of the protein fibroin and sericin (and some other little things), it’s called “raw silk”, it is thread-like and the caterpillar wraps it around itself, forming a cocoon around itself. First, the caterpillar forms an outer fluff (see in the photo, it’s shaggy), and then inside this fluff wraps the main mass of silk thread around itself.
Traditional Thai mulberry silk - from these yellow cocoons that are produced by the silkworm Bombix Mori
These cocoons are urgently collected and transported to silk spinning factories in order to catch the moment of metamorphosis of the pupa into a butterfly... the fact is that when the pupa in the cocoon turns into a butterfly (the butterfly does not have a mouthpart), it secretes a proteolytic enzyme (an enzyme that destroys the silk shell of the cocoon , called protease) to get out and fly away to mate. But the cocoon is a CONTINUOUS long thread of silk (from 300 to 900 meters), which the butterfly has wound around itself, and if you pierce the cocoon, you will not get a continuous thread, but short stubs... These stubs are also used, but it will not be high-quality silk thread, it will be a completely different product...
So, the cocoons are taken to a silk spinning factory to extract silk from them. Now, instead of a large factory, there are small handicraft workshops, but this has not changed the essence of the process, and the quality of the products remains excellent.
This is how silk cocoons are steamed and unwoven into threads, Margilan, Uzbekistan
First, the cocoons are sorted by size and color. Then, in order to kill the under-butterfly inside the cocoon, these cocoons are steamed in hot water (boiled, in short). The cocoons swell, part of the silk protein mixture from which the caterpillar made the cocoon dissolves in water (this is the substance I wrote about it above; the caterpillar does not secrete pure silk proteins, but a mixture of different proteins; some of them are actually silk proteins (fibroin) , and others are like glue for gluing silk threads together to form a cocoon (sericin + resins and something else), the cocoon itself feels dense to the touch, like thin felt...). So this kind of glue dissolves in water, releasing the silk threads. Now we need to unwind the cocoons, but it’s not easy.
Silkworm cocoons in hand, Margilan, Uzbekistan. They begin to unwind the cocoons on threads
In large silk-spinning factories, the process of unwinding cocoons is mechanized, but in small farms it is done manually... I won’t say exactly how, but they grab the threads (look at the photo) and begin to pull them, essentially unwinding the cocoons... What follows is the subtleties of the process: a thread of raw silk is formed from 3-10 threads from cocoons, if one of the threads breaks or ends, then a new thread is attached, simply glued: the remains of adhesive sericin are what connect all the tiny threads together. But I’d better say that boiled silkworm pupae (from cocoons) are often used for food. The photo shows cocoons and their contents, that is, silkworm pupae
White cocoons and silkworm pupae. Boiled dolls are eaten in Korea
In South Korea, for example, they are a delicacy (I myself saw how they are sold on the streets and eaten, brrrrr.. this popular snack is called 번데기 or Beondegi, in my opinion they have such a characteristic and disgusting smell...)
Silkworm snack boiled silkworm pupae
Raw silk (which is pulled from the cocoons) is wound into skeins. In the left corner of the photo you can see a skein (a bunch hanging on a stick) of silk, and the thread is wound on a “drum”.
Reeling and spinning silk, Margilan, Uzbekistan
And below in the photo a woman is spinning a silk thread (that is, twisting it)
Just curious: the life cycle of the silkworm
In writing the article, I used information from my memory, and took some things from the articles of the master Ksenia Semencha and here http://www.suekayton.com/silk.htm, and bought scarves from Anastasia Bulavka. Part of the photo from the site http://www.projectbly.com/, part of https://www.flickr.com/photos/adam_jones/
People know a lot about the benefits of silk, but few people know the “creator” who gave this miracle to the world. Meet the mulberry caterpillar. For 5,000 years, this small, humble insect has been spinning silk thread.
Silkworms eat the leaves of mulberry (mulberry) trees. Hence the name silkworm.
These are very voracious creatures; they can eat for days without a break. That is why hectares of mulberry trees are specially planted for them.
Like any butterfly, the silkworm goes through four life stages.
- Larva.
- Caterpillar.
- A pupa located in a silk cocoon.
- Butterfly.
As soon as the caterpillar's head darkens, the lenching process begins. Usually the insect sheds its skin four times, the body becomes yellow, and the skin becomes dense. So the caterpillar moves to a new stage, becoming a pupa, which is located in a silk cocoon. Under natural conditions, the butterfly gnaws a hole in the cocoon and climbs out of it. But in sericulture, the process follows a different scenario. Manufacturers do not allow silkworm cocoons to “ripen” until the last stage. For two hours under high temperature ( 100 degrees), the caterpillar then dies.
Appearance of a wild silkworm
Butterfly with large wings. Domesticated silkworms are not very attractive (the color is white with dirty spots). Radically different from its “domestic relatives”, this is a very beautiful butterfly with bright large wings. Until now, scientists cannot classify this species, where and when it appeared.
In modern sericulture, hybrid individuals are used.
- Monovoltine, produces offspring once a year.
- Polyvoltine, produces offspring several times a year.
The silkworm cannot live without human care; it is not able to survive in the wild. The silkworm caterpillar is not able to get food on its own, even if it is very hungry; it is the only Butterfly that cannot fly, which means it is not capable of getting food on its own.
Useful properties of silk thread
The productive ability of the silkworm is simply unique; in just a month it is capable of increasing its weight ten thousand times. At the same time, the caterpillar manages to lose “extra pounds” four times within a month.
To feed thirty thousand caterpillars you will need a ton of mulberry leaves, enough for the insects to weave five kilograms of silk thread. The usual production rate of five thousand caterpillars yields one kilogram of silk thread.
One silk cocoon gives 90 grams natural fabric. The length of one of the silk cocoon threads can exceed 1 km. Now imagine how much work a silkworm needs to do if, on average, 1,500 cocoons are spent on one silk dress.
Silkworm saliva contains sericin, a substance that protects silk from pests such as moths and mites. The caterpillar secretes matting substances of sheer origin (silk glue) from which it weaves a silk thread. Despite the fact that most of this substance is lost during the manufacturing process of silk fabric, the little that remains in the silk fibers can protect the fabric from the appearance of dust mites.
Thanks to serecin, silk has hypoallergenic properties. Due to its elasticity and incredible strength, silk thread is used in surgery for suturing. Silk is used in aviation; parachutes and balloon shells are sewn from silk fabric.
Silkworms and cosmetics
Interesting fact. Few people know that a silk cocoon is an invaluable product; it is not destroyed even after all the silk threads have been removed. Empty cocoons are used in cosmetology. They are used to prepare masks and lotions not only in professional circles, but also at home.
Silkworm food for gourmets
Few people know about the nutritional properties of the mulberry caterpillar. This ideal protein product, it is widely used in Asian cuisine. In China, maggots are steamed and grilled, seasoned with a huge amount of spices, and you won’t even understand what is “on the plate.”
In Korea, half-raw silkworms are eaten and lightly fried. This is a good source of protein.
Dried caterpillars are commonly used in Chinese and Tibetan folk medicine. The most interesting thing is that mold fungi are added to the “medicine”. That's how useful the silkworm is.
What good intentions lead to
Few people know that the gypsy moth, which is a major pest of the US forestry industry, was spread as a result of a failed experiment. As they say, I wanted the best, but what happened was the following.
How many silkworm cocoons do you think are needed to make one pair of silk stockings? And why do you think luxury tights brands rely not on innovation, but on naturalness? Silk is still impossible to synthesize. This is called the silk mystery. Scientists learned the formula of the silk molecule and studied the structure of silk fiber. But no one has yet succeeded in synthesizing silk.
To weave one square meter of silk fabric, you need a thread unwound from three thousand five hundred cocoons.
To make one kimono you need about 9,000 cocoons, one tie - about 140, one silk scarf - more than 100 cocoons.
The process of producing products from natural silk is very labor-intensive. Manual labor is required at the most important stage - unwinding the mulberry cocoon.
The length of the silk thread reaches 800 - 1000 m. The thread has a triangular cross-section and, like a prism, reflects light, which causes a beautiful iridescence and shine. The length of the thread contained in silkworm cocoons reaches 3700 meters, but only 400-600, rarely 900 meters can be unwound from it.
Let's calculate how many silkworm cocoons are needed to make one pair of silk stockings or tights.
The weight of the silk thread is 1-2 denier. Let's assume that our thread is of the highest quality and weighs 1 denier. The average weight of a pair of silk tights or stockings is 150 grams. 1 denier equals 1.275 grams.
It turns out that the weight of a pair in denier is approximately 117. Convert to meters. We get about 1058820 m - a million meters! Even if it was possible to extract a thread 1000 m long from the cocoons, then 1058 cocoons were required for just one pair of stockings. And if the length of the thread was 800 m, then 1320 cocoons!
Over the last millennium, silk has fallen in price significantly. But, due to the fact that the production of silk thread still involves a huge amount of manual labor, the price of silk stockings and tights is still high. By the way, do you know that Italy is one of the leading countries in the production of natural silk? In Italy, and not only in China, the silkworm feels great and therefore it is possible to produce a large number of silk stockings and underwear here.
Stockings made from real silk do not electrify, look great on your feet and give a delightful tactile sensation. If you don’t remember that one pair of stockings required more than 1000 silkworm cocoons...
How many silkworm cocoons does it take to make a pair of stockings? © Bracatus. All materials on this site are subject to copyright (including design). Copying, distribution (including by copying to other sites and resources on the Internet) or any other use of information and objects without the prior consent of the copyright holder is prohibited.
The silkworm or silkworm belongs to the silkworm family. This type of insect got its name due to its feeding habits. The silkworm can only feed on the leaves of the mulberry tree. The silkworm is a completely domesticated insect and is not found in the wild today. The ancestors of the silkworm are considered to be wild mulberry worms, which were tamed and domesticated long before our era in China.
The silkworm is a fairly large insect. Adults can reach 6 cm in wingspan. The insects are quite massive for their size and have practically lost the ability to fly.
The life cycle of the silkworm consists of several stages and metamorphoses. After mating, the female lays about 500 eggs, which eventually turn into a caterpillar. The caterpillars grow quite quickly and shed their skin several times.
Silkworm caterpillars are often called silkworms due to their appearance. The appearance of a silkworm caterpillar can be seen in the photo. The caterpillars feed on mulberry leaves without interruption throughout the day. Thanks to this intensive feeding, the caterpillars grow very quickly, molt several times, and then turn into pupae.
After about a month and a half, the mulberry worm begins to pupate. The worms move more and more slowly and have difficulty turning their heads. A slowdown in activity indicates preparation for pupation. The caterpillar begins to produce a continuous thread of silk, forming a dense cocoon around itself. Silkworm pupae are formed inside the cocoon. The silk thread from which silkworm cocoons are formed can reach up to 1.5 km. Medium cocoons are usually formed with 400 -800 meters of silk thread.
In the photo below you can see a mature silkworm cocoon.
Silkworm cocoons come in different colors - greenish, yellow, pink and white. The cocoon is fully formed within 2-3 days. After about 2-3 weeks, a butterfly emerges from the cocoon. But during commercial breeding of silkworms, they do not wait for the butterfly to come out of the cocoon. Pupated caterpillars are placed for a couple of hours at a temperature of 100°C, which causes the death of the pupa inside the cocoon. After the death of the pupa, the thread unwinds more easily.
Interestingly, adult butterflies do not feed throughout their lives. Silkworm butterflies have an underdeveloped chewing apparatus and are simply unable to consume food. A butterfly can live without food for several days. This period is just enough to lay eggs.
There are several types of silkworm depending on their habitat.
Types of mulberry worms:
Japanese;
Chinese;
Korean;
Indian;
European;
Persian;
Mulberry worms of different species differ in the size of the individuals, as well as color. Cocoons also differ in size, shape and amount of silk. Different types of silkworms are characterized by different durations of the ripening period and frequency of yield.
Sericulture
Mulberry worms are most often used in sericulture. Silk production dates back to ancient times and occupied an important place in the economies of eastern countries. Today, the main silk producing countries are India and China. Mulberry worms are also bred quite widely in European countries, Korea, India and Russia.
Mulberry worms with white cocoons are bred for production purposes. Most often, Japanese, Chinese and European species of silkworms are bred in production. With the development of silkworming, new mixed breeds of silkworms are constantly being developed.
In large industries, the eggs of mulberry worms are grown in special incubators, where they turn into larvae in a couple of days. The larvae are then placed in special feeders with mulberry leaves, where they feed and grow. After the larvae grow, they are transferred to special cells where they will form a cocoon. The larvae begin to produce silk thread when they find the necessary support for fixation. Rotating their heads to the sides, the larvae form a frame, and then crawl inside and complete the formation of the cocoon.
To obtain silk thread in production, they do not wait until the moth is born. After a couple of days, the pupated individuals are collected and treated with steam. When treated with steam, the larvae inside die and the threads are easier to unwind. After steam, the cocoons are immersed in boiling water, which makes the thread more pliable.
In eastern countries, home breeding of silkworms is still widespread. The larvae are manually transferred to trays covered with mulberry leaves, and straw branches or lattice trays are used to form a cocoon.
It takes about two thousand pupated caterpillars to produce one silk item, such as a dress. Silk products are very expensive, which is due to the labor-intensive process of obtaining silk threads. With the development of technology, synthetic threads are replacing silk. But reviews about the characteristics of natural silk do not require additional comments. Natural fabric has a special richness and charm, and products made from silk thread are still considered an indicator of status and good taste.
Mulberry worms in cosmetology
Natural silk contains the proteins sericin and fibroin. Sericin dissolves well in warm water, forming a sticky mixture. Fibroin is not able to dissolve in water. Cocoons become sticky after immersion in water, which is due to the dissolution of sericin. Sericin moisturizes the skin and also prevents the formation of wrinkles. Well-hydrated skin ages slower.
Mulberry cocoons can be used for peeling procedures. Silk thread fibers exfoliate well the upper dead layer of cells. After peeling using silkworm threads, the skin becomes elastic and smooth.
For cosmetic purposes, empty cocoons are used, from which the larvae are first removed. Also, for cosmetic purposes, you can use the cocoons from which the butterfly flew.
The photo shows how the larvae are taken out of the cocoon through the hole.
According to women's reviews, using cocoons is very simple and convenient. They are placed on the index fingers and moved along the massage lines of the face. Before the procedure, the face must be cleaned and washed with warm water. Before pilling, silk fibers must be moistened in water. The best reviews about the effectiveness of using silkworm cocoons are left by people after a course of several peeling procedures.
Silk thread fibers work well against enlarged pores and blackheads. Before the peeling procedure, the facial skin must be cleansed using a cleanser.
Of course, reviews of instant rejuvenation are usually greatly exaggerated, but the proteins sericin and fibroin can really slow down the aging process.