The production of silk originates in China in the Neolithic (Yangshao culture, 4th millennium BC). Silk remained confined to China until the Silk Road opened at some point during the later half of the 1st millennium BC. China maintained its virtual monopoly over silk production for another thousand years. Not confined to clothing, silk was also used for a number of other applications, including writing, and the color of silk worn was an important guide of social class during the Tang dynasty.
Silk cultivation spread to Japan around 300 AD, and, by 552 AD, the Byzantines managed to obtain silkworm eggs and were able to begin silkworm cultivation. The Arabs also began to manufacture silk at the same time. As a result of the spread of sericulture, Chinese silk exports became less important, although they still maintained dominance over the luxury silk market. The Crusades brought silk production to Western Europe, in particular to many Italian states, which saw an economic boom exporting silk to the rest of Europe. Changes in manufacturing techniques also began to take place during the Middle Ages, with devices such as the spinning wheel first appearing. During the 16th century, France joined Italy in developing a successful silk trade, though the efforts of most other nations to develop a silk industry of their own were unsuccessful.
The Industrial Revolution changed much of Europe's silk industry. Due to innovations on spinning cotton, cotton became much cheaper to manufacture and therefore caused more expensive silk production to become less mainstream. New weaving technologies, however, increased the efficiency of production. Among these was the Jacquard loom, developed for silk embroidery. An epidemic of several silkworm diseases caused production to fall, especially in France, where the industry never recovered. In the 20th century Japan and China regained their earlier role in silk production, and China is now once again the world's largest producer of silk. The rise of new fabrics such as nylon reduced the prevalence of silk throughout the world, and silk is now once again a rare luxury good, much less important than in its heyday.
The earliest evidence of silk was found at the sites of Yangshao culture in Xia County, Shanxi, where a silk cocoon was found cut in half by a sharp knife, dating back to between 4000 and 3000 BC. The species was identified as Bombyx mori, the domesticated silkworm. Fragments of primitive loom can also be seen from the sites of Hemudu culture in Yuyao, Zhejiang, dated to about 4000 BC. The earliest example of silk fabric is from 3630 BC, and was used as wrapping for the body of a child. The fabric comes from a Yangshao site in Qingtaicun at Rongyang, Henan. Scraps of silk were found in a Liangzhu culture site at Qianshanyang in Huzhou, Zhejiang, dating back to 2700 BC. Other fragments have been recovered from royal tombs in the Shang dynasty (c. 1600 - c. 1046 BC).
During the later epoch, the Chinese lost their secret to the Koreans, the Japanese, and, later, the Indians, as these cultures discovered how to make silk. Allusions to the fabric in the Old Testament show that it was known in western Asia in biblical times. Scholars believe that starting in the 2nd century BC the Chinese established a commercial network aimed at exporting silk to the West. Silk was used, for example, by the Persian court and its king, Darius III, when Alexander the Great conquered the empire. Even though silk spread rapidly across Eurasia, with the possible exception of Japan its production remained exclusively Chinese for three millennia.
The writings of Confucius and Chinese tradition recount that, in about 3000 BC, a silk worm's cocoon fell into the tea cup of the empress Leizu. Wishing to extract it from her drink, the 14-year-old girl began to unroll the thread of the cocoon.
She then had the idea to weave some of it, so she kept some for herself. Having observed the life of the silk worm on the recommendation of her husband, the Yellow Emperor, she began to instruct her entourage in the art of raising silk worms, sericulture. From this point, the girl became the goddess of silk in Chinese mythology. Silk eventually left China via the heir of a princess who was promised to a prince of Khotan. This probably occurred in the early 1st century AD. The princess, refusing to go without the fabric that she loved, would finally break the imperial ban on silk-worm exportation.
Though silk was exported to foreign countries in great amounts, sericulture remained a secret that the Chinese carefully guarded. Consequently, other peoples invented wildly varying accounts of the source of the incredible fabric.
In classical antiquity, most Romans, great admirers of the cloth, were convinced that the Chinese took the fabric from tree leaves. This belief was affirmed by Seneca the Elder in his Phaedra and by Virgil in his Georgics. Notably, Pliny the Elder knew better. Speaking of the bombyx or silk moth, he wrote in his Natural History "They weave webs, like spiders, that become a luxurious clothing material for women, called silk."
In China, silk-worm farming was originally restricted to women, and many women were employed in the silk-making industry. Even though some saw the development of a luxury product as useless, silk provoked such a craze among high society that the rules in the Li Ji were used to limit its use to the members of the imperial family. For approximately a millennium, the right to wear silk was reserved for the emperor and the highest dignitaries. Silk was, at the time, a sign of great wealth, because of its shimmering appearance. This appearance was due to silk's prism-like shape/structure, which refracted light from every angle. After some time, silk gradually extended to other classes of Chinese society, like the noble class and such. Silk began to be used for decorative means and also in less luxurious ways: musical instruments, fishing, and bow making. Peasants did not have the right to wear silk until the Qing dynasty (1644-1911).
Paper was one of the greatest discoveries of ancient China. Beginning in the 3rd century BC paper was made in all sizes with various materials. Silk was no exception, and silk workers had been making paper since the 2nd century BC. Silk, bamboo, linen, wheat and rice straw were all used, and paper made with silk became the first type of luxury paper. Researchers have found an early example of writing done on silk paper in the tomb of a marchioness who died around 168, in Mawangdui, Changsha, Hunan. The material was certainly more expensive, but also more practical than bamboo slips. Treatises on many subjects, including meteorology, medicine, astrology, divinity, and even maps written on silk have been discovered.
During the Han dynasty, silk became progressively more valuable in its own right, and became more than simply a material. It was used to pay government officials and compensate citizens who were particularly worthy. By the same token that one would sometimes estimate the price of products according to a certain weight of gold, the length of the silk cloth became a monetary standard in China (in addition to bronze coins). The wealth that silk brought to China stirred envy in neighboring peoples. Beginning in the 2nd century BC, the Xiongnu regularly pillaged the provinces of the Han Chinese for around 250 years. Silk was a common offering by the emperor to these tribes in exchange for peace.
Silk is described in a chapter of the Fan Shengzhi shu from the Western Han (206 BC - 9 AD). There is a surviving calendar for silk production in an Eastern Han (25 - 220 AD) document. The two other known works on silk from the Han period are lost.
The military payrolls tell us that soldiers were paid in bundles of plain silk textiles, which circulated as currency in Han times. Soldiers may well have traded their silk with the nomads who came to the gates of the Great Wall to sell horses and furs.
For more than a millennium, silk remained the principal diplomatic gift of the emperor of China to his neighbors or to his vassals. The use of silk became so important that silk (?) soon constituted one of the principal radicals of Chinese script.
Broadly speaking, the use of silk was regulated by a very precise code in China. For example, the Tang Dynasty and Song Dynasty imposed upon bureaucrats the use of particular colors according to their functions in society. Under the Ming, silk began to be used in a series of accessories: handkerchiefs, wallets, belts, or even an embroidered piece of fabric displaying dozens of animals, real or mythical. These fashion accessories remained associated with a particular position: there was a specific bonnet for warriors, for judges, for nobles, and others for religious use. The women of high Chinese society heeded codified practices and used silk in their garments to which they added countless motifs. A 17th-century work, Jin Ping Mei, gives a description of one such motif:
Golden lotus having a quilted backgammon pattern, double-folded, adorned with savage geese pecking at a landscape of flowers and roses; the dress' right figure had a floral border with buttons in the form of bees or chrysanthemums.
The earliest examples of silk production outside China are from silk threads discovered from the Chanhudaro site in the Indus Valley Civilisation which are dated to 2450-2000 BC. The analysis of the silk fibres shows presence of reeling and sericulture. This finding predates the one found in Nevasa in peninsular India in 1500 BC. The Siberian Ice Maiden discovered from the Pazyryk burials was found clad in a long crimson and white striped woolen skirt and white felt stockings. Her yellow blouse was originally thought to be made of wild tussah silk but closer examination of the fibers indicate the material is not Chinese but was a wild silk which came from somewhere else, perhaps India.
Numerous archaeological discoveries show that silk had become a luxury material appreciated in foreign countries well before the opening of the Silk Road by the Chinese. For example, silk has been found in the Valley of the Kings in a tomb of a mummy dating from 1070 BC. First the Greeks, then the Romans began to speak about the Seres (people of silk), a term to designate the inhabitants of the far-off kingdom, China. According to certain historians, the first Roman contact with silk was that of the legions of the governor of Syria, Crassus. At the Battle of Carrhae, near to the Euphrates, the legions were said to be so surprised by the brilliance of the banners of Parthia that they fled.
The silk road toward the west was opened by the Chinese in the 2nd century AD. The main road left from Xi'an, going either to the north or south of the Taklamakan desert, one of the most arid in the world, before crossing the Pamir Mountains. The caravans that employed this method to exchange silk with other merchants were generally quite large, including from 100 to 500 people as well as camels and yaks carrying around 140 kg (300 lb) of merchandise. They linked to Antioch and the coasts of the Mediterranean, about one year's travel from Xi'an. In the south, a second route went by Yemen, Burma, and India before rejoining the northern route.
Not long after the conquest of Egypt in 30 BC regular commerce began between the Romans and Asia, marked by the Roman appetite for silk cloth coming from the Far East, which was then resold to the Romans by the Parthians. The Roman Senate tried in vain to prohibit the wearing of silk, for economic reasons as well as moral ones. The import of Chinese silk resulted in vast amounts of gold leaving Rome, to such an extent that silk clothing was perceived as a sign of decadence and immorality.
I can see clothes of silk, if materials that do not hide the body, nor even one's decency, can be called clothes. ... Wretched flocks of maids labour so that the adulteress may be visible through her thin dress, so that her husband has no more acquaintance than any outsider or foreigner with his wife's body.
In the late Middle Ages, transcontinental trade over the land routes of the Silk Road declined as sea trade increased. The Silk Road was a significant factor in the development of the civilizations of China, India, Ancient Egypt, Persia, Arabia, and Ancient Rome. Though silk was certainly the major trade item from China, many other goods were traded, and various technologies, religions and philosophies, as well as the bubonic plague (the "Black Death"), also traveled along the Silk Routes. Some of the other goods traded included luxuries such as silk, satin, hemp and other fine fabrics, musk, other perfumes, spices, medicines, jewels, glassware, and even rhubarb, as well as slaves. China traded silk, teas, and porcelain; while India traded spices, ivory, textiles, precious stones, and pepper; and the Roman Empire exported gold, silver, fine glassware, wine, carpets, and jewels. Although the term the Silk Road implies a continuous journey, very few who traveled the route traversed it from end to end; for the most part, goods were transported by a series of agents on varying routes and were traded in the bustling markets of the oasis towns. The main traders during Antiquity were the Indian and Bactrian traders, then from the 5th to the 8th century AD the Sogdian traders, then afterward the Arab and Persian traders.
Although silk was well known in Europe and most of Asia, China was able to keep a near monopoly on silk production. The monopoly was defended by an imperial decree, condemning to death anyone attempting to export silkworms or their eggs. Only around the year 300 AD did a Japanese expedition succeed in taking some silkworm eggs and four young Chinese girls, who were forced to teach their captors the art of sericulture. Techniques of sericulture were subsequently introduced to Japan on a larger scale by frequent diplomatic exchanges between the 8th and 9th centuries.
Starting in the 4th century BC silk began to reach the Hellenistic world by merchants who would exchange it for gold, ivory, horses or precious stones. Up to the frontiers of the Roman Empire, silk became a monetary standard for estimating the value of different products. Hellenistic Greece appreciated the high quality of the Chinese goods and made efforts to plant mulberry trees and breed silkworms in the Mediterranean basin. Sassanid Persia controlled the trade of silk destined for Europe and Byzantium. The Greek word for "silken" was ?, from the name of the Seres (), according to Strabo the people from whom silk was first obtained. The Greek word gave rise to Latin sericum and ultimately Old English sioloc, Middle English silk.
According to a story by Procopius, it was not until 552 AD that the Byzantine emperor Justinian obtained the first silkworm eggs. He had sent two Nestorian monks to Central Asia, and they were able to smuggle silkworm eggs to him hidden in rods of bamboo. While under the monks' care, the eggs hatched, though they did not cocoon before arrival. The church manufacture in the Byzantine Empire was thus able to make fabrics for the emperor, with the intention of developing a large silk industry in the Eastern Roman Empire, using techniques learned from the Sassanids. These gynecia had a legal monopoly on the fabric, but the empire continued to import silk from other major urban centres on the Mediterranean. The magnificence of the Byzantine techniques was not a result of the manufacturing process, but instead of the meticulous attention paid to the execution and decorations. The weaving techniques they used were taken from Egypt. The first diagrams of semple looms appeared in the 5th century.
The Arabs, with their widening conquests, spread sericulture across the shores of the Mediterranean, leading to the development of sericulture in North Africa, Andalusia and Sicily. The interactions among Byzantine and Muslim silk-weaving centers of all levels of quality, with imitations made in Andalusia and Lucca, among other cities, have made the identification and date of rare surviving examples difficult to pinpoint.
While the Chinese lost their monopoly on silk production, they were able to re-establish themselves as major silk supplier (during the Tang dynasty), and to industrialize their production in a large scale (during the Song dynasty). China continued to export high-quality fabric to Europe and the Near East along the silk road.
After the start of the Crusades, techniques of silk production began to spread across Western Europe. In 1147 while Byzantine emperor Manuel I Komnenos was focusing all his efforts on the Second Crusade, the Norman king Roger II of Sicily attacked Corinth and Thebes, two important centres of Byzantine silk production. They took the crops and silk production infrastructure, and deported all the workers to Palermo, thereby causing the Norman silk industry to flourish. The sack of Constantinople by the Fourth Crusade in 1204 brought decline to the city and its silk industry, and many artisans left the city in the early 13th century. Italy developed a large domestic silk industry after 2000 skilled weavers came from Constantinople. Many also chose to settle in Avignon to furnish the popes of Avignon.
The sudden boom of the silk industry in the Italian state of Lucca, starting in the 11th and 12th centuries was due to much Sicilian, Jewish, and Greek settlement, alongside many other immigrants from neighbouring cities in southern Italy. With the loss of many Italian trading posts in the Orient, the import of Chinese styles drastically declined. Gaining momentum, in order to satisfy the rich and powerful bourgeoisie's demands for luxury fabrics, the cities of Lucca, Genoa, Venice and Florence were soon exporting silk to all of Europe. In 1472 there were 84 workshops and at least 7000 craftsmen in Florence alone.
Silk was made using various breeds of lepidopterans, both wild and domestic. While wild silks were produced in many countries, there is no doubt that the Chinese were the first to begin production on such a large scale, having the most effective species for silk production, the Bombyx mandarina and its domesticated descendant B. mori. Chinese sources claim the existence of a machine to unwind silkworm cocoons in 1090. The cocoons were placed in a large basin of hot water, the silk would leave the cauldron by tiny guiding rings, and would be wound onto a large spool, thanks to a backwards and forward motion. Little information exists about spinning techniques in use in China. The spinning wheel, in all likelihood moved by hand, was known by the beginning of the Christian era. The first accepted image of a spinning wheel appears in 1210. There is an image of a silk spinning machine powered by a water wheel that dates to 1313.
More information is known about the looms used. The Nung Sang Chi Yao, or Fundamentals of Agriculture and Sericulture, compiled around 1210, is rich with pictures and descriptions, many pertaining to silk. It repeatedly claims the Chinese looms to be far superior to all others. It speaks of two types of loom that leave the worker's arms free: the draw loom, which is of Eurasian origin, and the pedal loom which is attributed to East Asian origins. There are many diagrams originate in the 12th and 13th centuries. When examined closely, many similarities between Eurasian machines can be drawn. Since the Jin dynasty, the existence of silk damasks has been well recorded, and since the 2nd century BC, four-shafted looms and other innovations allowed the creation of silk brocades.
The high Middle Ages saw continued use of established techniques for silk manufacture without any changes to speak of, neither in materials nor in tools used. Between the 10th and 12th centuries, small changes began to appear, though the changes of the 13th century were much larger and more radical. In a short time, new fabrics began to appear; hemp and cotton each also had their own particular techniques of manufacture. Known since Roman times, silk remained a rare and expensive material. Byzantine magnaneries in Greece and Syria (6th to 8th centuries), and those of the Arabs in Sicily and Spain (8th to 10th centuries) were able to supply the luxury material in a much greater abundance.
The 13th century saw an already changing technology undergo many dramatic changes. It is possible that, as with in England at the end of the 18th century, advances in the textile industry were a driving force behind advances in technology as a whole. Silk indeed occupies a privileged place in history on account of this.
At the start of the 13th century, a primitive form of milling the silk threads was already in use. In 1221 Jean de Garlande's dictionary, and in 1226, Étienne Boileau's Livre des métiers (Tradesman's Handbook) enumerated many types of devices which can only have been doubling machines. The instruments used were further perfected in Bologna between 1270 and 1280. From the start of the 14th century, many documents allude to the use of devices that were quite complex.
The reel, originally developed for the silk industry, now has multiple uses. The earliest surviving depiction of a European spinning wheel is a panel of stained glass in the Cathedral of Chartres.Bobbins and warping machines appear together in the stained glass at Chartres and in a fresco in the Cologne Kunkelhaus (ca 1300). It is possible that the toothed warping machine was created by the silk industry; it allowed the warp to be more uniform and allowed the warp to be of a longer length.
Starting at the end of the 14th century, no doubt on account of the devastation caused mid-century by the Black Death, there was a general shift towards less expensive techniques. Many things which would have earlier been completely forbidden by the guilds were now commonplace (using low quality wool, carding, etc.). In the silk industry, the use of water-powered mills grew, and by the 15th century, the loom designed by Jean le Calabrais saw nearly universal use.
Italian silk cloth was very expensive, as much a result of the cost of the raw material as of the production costs. The craftsmen in Italy proved unable to keep up with the exigencies of French fashion, which continuously demanded lighter and less expensive materials. These materials were used for clothing, and garment production began to be done locally. Nevertheless, Italian silk long remained among the most prized, mostly for furnishings and the brilliant colours of the dyes.
Following the example of the wealthy Italian city-states of the era, such as Venice, Florence, and Lucca, which had become the center of the luxury-textile industry, Lyon obtained a similar function in the French market. In 1466, King Louis XI decided to develop a national silk industry in Lyon. In the face of protests by the Lyonnais, he conceded and moved the silk fabrication to Tours, but the industry in Tours stayed relatively marginal. His main objective was to reduce France's trade deficit with the Italian states, which caused France to lose 400,000 to 500,000 golden écus a year. It was under Francis I in around 1535 that a royal charter was granted to two merchants, Étienne Turquet and Barthélemy Naris, to develop a silk trade in Lyon. In 1540, the king granted a monopoly on silk production to the city of Lyon. Starting in the 16th century, Lyon became the capital of the European silk trade, notably producing many reputable fashions. Gaining confidence, the silks produced in the city began to abandon the original oriental styles in favor of their own distinctive style, which emphasized landscapes. Thousand of workers, the canuts, devoted themselves to the flourishing industry. In the middle of the 17th century, over 14,000 looms were used in Lyon, and the silk industry fed a third of the city's population.
In the 18th and 19th centuries, Provence experienced a boom in sericulture that would last until the first world war, with much of the silk shipped north to Lyon. Viens and La Bastide-des-Jourdans are two of the communes of Luberon that profited the most from mulberry plantations that have since disappeared. However, silk centers still operate today.Working at home under the domestic system, silk spinning and silk treatment employed many people and increased the income of the working class.
England under Henry IV was also looking to develop a silk industry, but no opportunity arose until the revocation of the Edict of Nantes the 1680s, when hundreds of thousands of French Huguenots, many of whom were skilled weavers and experts in sericulture, began immigrating to England to escape religious persecution. Some areas, including Spitalfields saw many high-quality silk workshops spring up, their products distinct from continental silk largely by the colors used. Nonetheless, the British climate prevented England's domestic silk trade from becoming globally dominant.
Many envisioned starting a silk industry in the British colonies in America, starting in 1619, under the reign of King James I of England. The silk industry in the colonies never became very large. Likewise, silk was introduced to numerous other countries, including Mexico, where it was brought by Cortez in 1522. Only rarely did these new silk industries grow to any significant size.
The start of the Industrial Revolution was marked by a massive boom in the textile industry, with remarkable technological innovations made, led by the cotton industry of Great Britain. In its early years, there were often disparities in technological innovation between different stages of fabric manufacture, which encouraged complementary innovations. For example, spinning progressed much more rapidly than weaving.
The silk industry, however, did not gain any benefit from innovations in spinning, as silk is naturally already a thread. Making silk, silver, and gold brocades is a very delicate and precise process, with each colour needing its own dedicated shuttle. In the 17th and 18th centuries progress began to be made in the simplification and standardization of silk manufacture, with many advances following one after another. Bouchon and Falcon's punched card loom appeared in 1775, later improved on by Jacques de Vaucanson. Later, Joseph-Marie Jacquard improved on the designs of Falcon and Vaucanson, introducing the revolutionary Jacquard loom, which allowed a string of punched cards to be processed mechanically in the correct sequence. The punched cards of the Jacquard loom were a direct precursor to the modern computer, in that they gave a (limited) form of programmability. Punched cards themselves were carried over to computers, and were ubiquitous until their obsolescence in the 1970s. From 1801 embroidery became highly mechanized due to the effectiveness of the Jacquard loom. The mechanism behind the Jacquard loom even allowed complex designs to be mass-produced.
The Jacquard loom was immediately denounced by workers, who accused it of causing unemployment, but soon it had become vital to the industry. The loom was declared public property in 1806, and Jacquard was rewarded with a pension and a royalty on each machine. In 1834 there were a total of 2885 Jacquard looms in Lyon alone. The Canut revolt in 1831 foreshadowed many of the larger worker uprisings of the Industrial Revolution. The canuts occupied the city of Lyon, and would not relinquish it until a bloody repression by the army, led by Marshal Soult. A second revolt, similar to the first, took place in 1834.
The first silkworm diseases began to appear in 1845, creating an epidemic. Among them are pébrine, caused by the microsporidia Nosema bombycis, grasserie, caused by a virus, flacherie, caused by eating infected mulberry leaves or white muscardine disease, caused by the fungus Beauveria bassiana. The epidemic grew to a massive scale, and after having attacked the silkworms, other viruses began to infect the mulberry trees. The chemist Jean-Baptiste Dumas, French minister of agriculture, was charged with stopping the epidemic. In face of sericulturers' call for help, he asked Louis Pasteur to study the disease, starting in 1865. For many years, Pasteur thought that pébrine was not a contagious disease. In 1870 he changed his view, and measures were enacted that caused the disease to decline.
Nevertheless, the increase in the price of silkworm cocoons and the reduction in importance of silk in the garments of the bourgeoisie in the 19th century caused the decline of the silk industry in Europe. The opening of the Suez Canal in 1869 and the silk shortage in France reduced the price of importing Asian silk, particularly from China and Japan.
Starting from the Long Depression (1873-1896), Lyonnais silk production had become totally industrialized, and hand looms were rapidly disappearing. The 19th century saw the textile industry's progress caused by advances in chemistry. The synthesis of aniline was used to make mauveine (aniline purple) dye and the synthesis of quinine was used to make indigo dye. In 1884 Count Hilaire de Chardonnet invented artificial silk and in 1891 opened a factory dedicated to the production of artificial silk (viscose), which cost much less and in part replaced natural silk.
[[Imag:Khotan-fabrics-sea-dipping|thumb|right|200px|A woman weaving with silk threads in Hotan, China.]] Following the crisis in Europe, the modernization of agriculture in Japan made it the world's foremost silk producer. By the early 20th century, rapidly industrializing Japan was producing as much as 60 percent of the world's raw silk, most exports shipping through the port of Yokohama. Italy managed to rebound from the crisis, but France was unable. Urbanization in Europe saw many French and Italian agricultural workers leave silk growing for more lucrative factory work. Raw silk was imported from Japan to fill the void. Asian countries, formerly exporters of raw materials (cocoons and raw silk), progressively began to export more and more finished garments.
During the Second World War, silk supplies from Japan were cut off, so western countries were forced to find substitutes. Synthetic fibres such as nylon were used in products such as parachutes and stockings, replacing silk. Even after the war, silk was not able to regain many of the markets lost, though it remained an expensive luxury product. Postwar Japan, through improvements in technology and a protectionist market policy, became the world's foremost exporter of raw silk, a position it held until the 1970s. The continued rise in the importance of synthetic fibres and loosening of the protectionist economy contributed to the decline of Japan's silk industry, and by 1975 it was no longer a net exporter of silk.
With its recent economic reforms, the People's Republic of China has become the world's largest silk producer. In 1996 it produced 58,000 tonnes out of a world production of 81,000, followed by India at 13,000 tonnes. Japanese production is now marginal, at only 2500 tonnes. Between 1995 and 1997 Chinese silk production went down 40% in an effort to raise prices, reminiscent of earlier shortages.