THE AGE OF GLASS

Glass is one of the oldest human-made materials, and its history is closely intertwined with the fate of humanity.

THE AGE OF GLASS

Types of glass art. 1897 / Getty Images

"Now we see as if through a dim glass, enigmatically..."

Apostle Paul.

First Corinthians 13:2

Pliny the Elder claimed that the Phoenicians invented glass. This mercantile seafaring people had brought glass beads, figurines, and, later, elegant round glass vessels to the markets of Greek cities and eventually to Rome for centuries. Hence, Pliny's confidence that the Phoenicians were the creators of glass.

"The history, as they say, is like this: a ship laden with nitri dropped anchor at this place; the merchants, intending to prepare food on the shore and not finding any stones nearby to place their pots on, used several pieces of nitri brought from the ship for this purpose. When the nitri was exposed to the action of fire and mixed with the sand of the shore, the merchants saw transparent drops of a certain liquid, previously unknown; and thus, glass was invented."

Nitri is natron, a decahydrate of sodium carbonate, a substance akin to soda. It was extracted in ancient Egypt on the shores of the soda lakes of the Natron Valley, for which this substance was named.

In the late twentieth century, several groups of enthusiastic scientists attempted to replicate the event described by Pliny. They tried in vain; no bonfire, not even the hottest, reached the temperature necessary to melt glass. Besides, the Phoenicians had no need to invent glass; it had been discovered long before them, likely by the Egyptians and possibly simultaneously in Mesopotamia, at least as early as the fourth millennium BCE. In Egypt, natron was used as a flux, an additive in the smelting process of copper and bronze, and small beads of fused glass were well-known to the metallurgists of that era. These beads adorn burial attire at some of the oldest archaeological finds.

One such bead, tiny and misshapen, measuring less than a centimeter in diameter and faintly green, is now treasured as an invaluable artifact at the Berlin Museum. Unearthed near Thebes by the archaeologist Flinders Petrie, it is thought to date back to the mid-fourth millennium BCE.

The Glass of the Pharaohs

Larger glass items emerged later, with the Egyptians deliberately starting to melt glass as a distinct material around two and a half thousand years before our era. They crafted vessels for fragrances, small figurines, and jewelry from it. This glass was often quite cloudy, containing numerous impurities. To create objects from it, they immersed clay molds into molten glass, effectively making them ceramics with a glass glaze. To create containers, they placed a metal rod inside the clay mold, which was later carefully removed from the resulting vessel and polished from the inside. Glass tiles for decoration, and ceramic plates sealed in a layer of glass also made their appearance and were sometimes used to embellish tombs.

The oldest surviving glass vessel, dating back to approximately 1500 BCE, is the bowl of Pharaoh Thutmose III, currently housed in the Munich Museum. As we can observe, this artifact falls into the category of glazed ceramics—charming, undoubtedly glass-like, but not quite glassware as we know it.

A Glass Chalice of Tuthmosis III. The State Museum of Egyptian Art. Munich. 1450

A Glass Chalice of Tuthmosis III. The State Museum of Egyptian Art. Munich. 1450

One of the most crucial properties of glass for humans, its transparency, remained largely unknown to the earliest civilizations that invented this material. They primarily regarded it as a glaze, appreciating its decorative qualities and exceptional smoothness.

Sidon and Rome

The Phoenicians, particularly those from Sidon, played a pivotal role in the development of glass technology. It is likely that glassblowing was invented in Sidon, and it was there that the art of creating relatively transparent glass through purification with manganese was pioneered and later adopted by the Romans.

Glassblowers. 14th century/Alamy

Glassblowers. 14th century/Alamy

Some of the Sidonian (and later Roman) vessels have survived to this day, with Pompeii and Herculaneum being particularly fruitful in terms of glass finds. Fragile pitchers and vases managed to endure beneath thick layers of volcanic ash. When we examine collections of Sidonian and Roman glass today, there is a temptation to affirm the rationality and utilitarian nature of the Roman mentality through this spectacle and contrast it with the Eastern inclination for opulence and sophistication. If Sidonian pitchers are elegant, intricately adorned, and often ribbed works of art, their Roman counterparts are mostly heavy, plain in form, and rather utilitarian in nature.

However, it's important to note that the Sidonians crafted their costly masterpieces primarily for export, targeting wealthy Mediterranean families. Some of these vessels were so expensive that they were treasured as family heirlooms, passed down through generations (a significant portion of Sidonian collections in museums was acquired from descendants and collectors). Meanwhile, Roman glassblowers produced more affordable glassware for everyday use, catering to a broader clientele with thinner wallets.

Thus, making sweeping conclusions would be unwise.

Windows Get a New Life

Transparent and relatively affordable glass, primarily developed in Rome, led to the creation of windows as we understand them today. The windows of Greek and later Roman houses were initially simple openings, quite small and narrow, designed to prevent thieves from sneaking in if the windows faced the street rather than an inner courtyard protected by a fence. Eventually, these windows received sturdy grilles. For serious weather conditions, windows were covered from the inside with wooden shutters or dense leather shields. The most primitive dwellings lacked windows altogether, relying on open doors or interior lighting through lamps when needed. The use of bull's bladder and later mica for windows became more common in the Middle Ages rather than in antiquity.

However, by the end of the first century BCE, glass windows had appeared in Rome. They were made from small pieces of thick glass, measuring a maximum of twenty by twenty centimeters, and were set into lead or wooden lattice frames. People of that time did not yet possess the technology to produce larger glass panels, and they wouldn't master this skill for quite some time.

In his monograph "History of Glass," historian Sergey Peskov writes:

"During the reign of Emperor Octavian Augustus (the first half of the 1st century), the art of glassmaking, which had previously only developed in the eastern provinces, spread throughout the vast empire. Workshops were established in Italy, Spain, Gaul, Britain, and Germany. Glass windows and glassware started to make their way into the daily lives of Romans. Of course, in ancient Rome, glass was not as affordable and widespread as it is today, but it remained reasonably accessible. Citizens of average means could afford it. The famous Roman orator Cicero declared, 'Poor is the one whose dwelling is not adorned with glass.'"

During this time, it seems they also started creating glass greenhouses for growing delicate southern plants. It is known, for instance, that Emperor Tiberius had a greenhouse complex where, among other things, cucumbers or melons (these fruits were considered closely related by the Romans and not distinctly different, unsurprisingly, as the Romans usually picked them not as the young green cucumbers that we favor, but as large, yellow, solid "melons") were grown for his table.

The Byzantine Monopoly

While Rome established its glassmaking workshops primarily in the north, the secrets of glass craftsmanship remained exclusively with Byzantium after the empire's division. Industrial glass production in the northern regions declined, and glass furnaces went dormant for a long time. While some rudimentary glasswork continued in semi-domestic settings, the secrets of glassmaking came to be regarded as mysterious, almost mystical knowledge. Every ruler who possessed a small glassmaking factory, where crooked and cloudy bottles were blown, guarded this knowledge as a profound secret, and glass became a symbol of luxury.

Byzantium emerged as the sole "glass superpower" globally, preserving the methods for producing transparent and even sheet glass (albeit in small sheets).

Certainly, glass was also produced in China and India. The earliest glass artifacts from these regions date back to the 2nd-3rd millennium BCE, but glass did not gain significant importance or widespread use there. India's hot climate did not require the use of window glass or greenhouses. China and Japan employed Eastern-style windows in their architecture, often wooden lattice frames covered with oiled paper. Magnificent Asian ceramics and Chinese porcelain met their needs for functional vessels and tableware. Thus, glass in the East remained primarily decorative—mostly beads, trinkets, pendants, and amulets.

Necklace made of Phoenician glass. 6th century BC/Wikimedia Commons

Necklace made of Phoenician glass. 6th century BC/Wikimedia Commons

In the dark ages of Europe, where porcelain was unknown, most people produced only primitive ceramics for the common folk—pots and bowls. The elite primarily used metalware —bronze, silver, or gold vessels, the extraordinary value of which rendered them royal treasures. Byzantine glass, richly decorated, colored, painted, and patterned, was esteemed nearly as much as gold.

Murano Glass

It is believed that the European glassmaking industry was rejuvenated by the Crusades. After the capture of Constantinople by the Crusaders in 1204, many artisans from the city chose to relocate away from such significant historical events. A group of glassblowers settled in Italy, where there were more glassmaking facilities, albeit primitive, compared to those in Constantinople. Venice had the largest number of glass artisans. Local authorities realized the value of attracting these refugees, promising them prosperity and safety.

This marked the beginning of the history of the renowned Murano glass, which would experience another remarkable resurgence when another group of skilled glassblowers fled Constantinople, this time from the Turkish invasion in the mid-15th century.

Since glass production is highly fire-prone, and the homes in medieval Venice were mostly wooden, glassmakers were relocated from the city to a small island near Venice - Murano - after a couple of fires. From there, they continued to work their miracles for the next five hundred years. Golden butterflies frozen in the walls of a goblet, bright flowers entwined on the bottom of a dish, a silver ribbon flowing inside a cup, shimmering with blue and green, flowing down the stem in fantastic patterns.

Generously financed and vigorously encouraged, the Murano masters initiated a true glass revolution. They created completely transparent, milky-white, ruby-red, cobalt-blue glass - every color was at their disposal, and they incorporated the entire rainbow into their creations. They embedded metals into glass, and they incorporated intricate designs. They mastered rolling glass into the thinnest, largest of sheets using stone rods - thus, the world came to know large glass panels and shop windows. They also excelled in stained glass, illuminating European cathedrals with vivid shadows. Mosaics, ceramics, and mirror production - everything glass was conceived and crafted in Murano.

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The Murano masters were held in exceptional esteem for their miraculous creations. They paid no taxes. They were freed from class restrictions - no one in Venice held a higher status than a master glassblower, regardless of their origins: glassblowers could be elected as doges, and they even had the right to marry patrician women.

For the privilege of performing miracles, the Murano masters gave up their freedom. Departure from Venice was forbidden to them for life by the law known as the "Masters of Glass Act," equating it to high treason and punishable by death. To carry out sentences, two-legged “hounds” were released to track down fugitives: squads of professional killers tasked with hunting down the fugitives and eliminating them, along with their entire families.

Certainly, the glass recipe itself was not like Newton's binomial; it was well-known. Quartz sand, soda, limestone. Mix everything and heat it. The secret lay in the craftsmanship, which was nearly impossible to convey orally or in writing at the time. Only personal experience and practice mattered - a skilled master knew a multitude of nuances, and their actions were often intuitive or traditional, meaning not particularly rational.

... When such a thin, moist film runs across the surface - reduce the blowing... grease the tool strictly with melted fat, stand on the left to avoid splashes, and cool only to a precise thickness and porosity - otherwise, the piece will explode...

Even today, in the age of videos and the information revolution, many professions require a transition from theoretical training to extensive practical training – let's consider doctors as an example.

Certainly, it was possible to independently discover all these secrets and master the techniques through trial and error – Europeans were also dedicated to such endeavors. Yet, it proved far more dependable to abduct a few Venetians. Venice's primary objective was to safeguard its monopoly on the world's finest glass. Consequently, those who threatened the economic stability of the republic had to be eliminated.

The most recent of such murders occurred in 1667 in Paris when two Venetian glassblowers, who had come to revitalize French glass production, were poisoned. The organization of these murders is attributed to the Venetian envoy, Justiniani. However, by that time, every respectable elector or duke already possessed their own glass factories, so the Venetians decided to reject intrigue and pursuit and simply continue making the world's finest glass (especially helped by the arrival of Napoleon's army in Venice, after which any talk of secret production ceased). Murano glass remains famous to this day, and the fact that it's acquired not only by thousands of aristocrats but also by millions of glass enthusiasts worldwide suggests that Venetian glassblowers haven't lost their touch.

Bohemian Glass

The only serious competitors to the Venetians in the market were the Bohemians. Today, we are well-acquainted with "Czech" or "Bohemian" crystal - but this heavy, glittering material, containing a significant amount of lead, is a relatively late invention. Originally, Bohemian workshops produced an entirely different kind of glass. This craft emerged around the 11th-12th century, and we don't know the exact origins (although it's reasonable to assume that Constantinople's refugees from the first wave eventually reached this region). But by the beginning of the 13th century, manuscripts began mentioning glass from Bohemia. Several workshops were located around the Šumava Mountains, a low mountain range whose depths contain nearly the entire periodic table, and the accessibility and variety of materials allowed Bohemian masters to continually experiment.

The earliest Bohemian glass usually contained various types of additional metals and minerals (always with plenty of chalk and potash), and its composition could be quite variable. In appearance, it didn't even resemble glass much; rather, it looked like some sort of decorative stone. Initially, Bohemians were not so much glassblowers as they were glasscutters - the material's plasticity allowed for this approach. Heavy carved goblets and bowls made of opaque, colorful glass were the first Bohemian products. They cost less than their Venetian counterparts. Gradually, Bohemians also mastered stained glass, which flooded all of Europe. By the 16th-17th centuries, Bohemian glass workshops had caught up with Venetians and, in some places, even surpassed them. The region had over a hundred glass factories, and each furnace eventually uncovered a curious and talented youth eager to discover a new glass recipe. Starting in the late 16th century, the most talented (and fortunate) young glassblowers were granted knighthood by King Rudolf II'siRudolf II (1552-1612) – Holy Roman Emperor. decree; after all, it was these glassblowers who filled the country's treasury with a golden and rather abundant stream of wealth.

Bohemian glass became the world’s second most famous glass after Venetian glass, preserving its original feature - multifacetedness created by carving. Engraving, faceting, chiseling, and polishing - this was the Bohemians' method of working with glass. Therefore, they were the ones most actively involved in implementing the invention of the Englishman George Ravenscroft - lead glass, which we now know as "crystal." This glass is not blown but cast and then subjected to faceting.

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The Glass of Modernity

The history of glass would remain incomplete without acknowledging the science that owes its existence to this remarkable material: optics. Although the first lenses, initially crafted by the Egyptians, were fashioned from polished quartz, the arrival of high-quality transparent glass enabled humanity to peer into previously uncharted realms—both the vast expanses of space and the minuscule dimensions of the microcosm.

Humanity's enduring experimentation with glass continues, even though many contemporary materials loosely relate to traditional glass. Take, for example, tempered glass, which fractures simply by cracking instead of shattering into sharp shards, offering enhanced safety in automobiles. There's also bulletproof glass, UV-blocking glass, and laminated glass designed to withstand extremely high temperatures for spacecraft windows. Smart glass, or "intelligent glass," can alter its properties when subjected to electrical currents, transitioning between matte, transparent, thermal insulating, or heat-conductive states as directed by the operator.

Notably, the liquid crystal screens adorning our smartphones are constructed using glass.

And thus, as you contemplate the tiny, faint bead resting alone on a black velvet backdrop at the Berlin Museum, a profound sense of reverence washes over you.

This bead was the first of its kind, and without it, the world as we know it may have never existed.

Simone Cenedese. Comet Glass Star-Murano. Veneto, Italy. 2007/Alamy

Simone Cenedese. Comet Glass Star-Murano. Veneto, Italy. 2007/Alamy

References

1. N.N. Kachalov, "Glass," Publisher of the USSR Academy of Sciences, 1959.

2. Sergey Peskov, "The History of Glass," Centrpoligraf, 2021.