No one really knows when, or where glass was first made, but since antiquity as a material, it has had an important place and impact on many different cultures.
It has also been utilized in many different forms.
From exotic Egyptian jewellery to the sleek sophistication of Pharaoh Tutankhamun’s glass headrest: to a product for vanity created at Venice or, one made for toasting exalted beauties and life in eighteenth century England, since the dawn of recorded time, glass in its many guises has fascinated humankind for thousands of years.
More lately in our own time its use in the fields of medical science and space research are again extending its properties, which only adds to the mystique surrounding it.
Its beginnings are romantic, especially if you want to enjoy the legend handed down by Roman historian Pliny the Elder. (AD 23-79).
He recorded that it was Phoenician merchants and sailors who discovered glass around 5000 BC, when they came ashore to eat on the shores of the River Belus.
It appears there were no stones to support their cooking-pots (even though the cargo of the ship was stone) so they placed lumps of soda underneath them.
When these became hot and fused with the sand on the beach, streams of an unknown liquid flowed: glass.
Soda is a relatively simple safe chemical known and used (in the form of natron) since ancient times as a cleaner, antiseptic and water softener.
Phoenician merchants and sailors were responsible for spreading knowledge about glass around the coasts of the Mediterranean.
The earliest man-made glass objects, of which fragments have been found, are mainly non-transparent glass beads. They emerged quite independently in Mycenae (Greece), Cathay (China) and the North Tyrol 3500 years before the Christ event.
Over the centuries throughout its adventurous journey the quality, chemical, composition and decoration of glass changed dramatically.
The development of the glass industry down the centuriess has been influenced by technical innovations, historical events, and continual changes in design, style and taste.
But what is glass?
Glass is a homogeneous material with a liquid (non-crystalline) molecular structure whose manufacturing process requires that its raw materials be heated to a temperature sufficient enough to produce a completely used melt, which when cooled rapidly becomes rigid without crystallizing.
The Egyptian glass industry was flourishing by 1500 BCE and the rise of the industry in the Middle East; saw Egypt and Syria at the forefront, a position they maintained for centuries.
The first known glass making manual discovered dates from seven centuries before the Christ event.
The method of manufacture was recorded on clay tablets in the remains of the library of the ancient Assyrian King Ashurbanipal (669-626) BC.
Instructions stress it is also necessary to placate the spirits and observe true ceremony when making glass if you want to produce a satisfactory product.
Silica sand is the key, with sodium carbonate and calcium oxide added.
The ancient Egyptians used soda for many common tasks, from brushing teeth to mummification of the dead. Blended with oil, it was also used as a kind of body soap.
It has many useful cleaning properties from softening water to removing oil, grease and alcohol stains. Although today soda has been superseded by the modern, factory produced, sodium bicarbonate.
Greek leader and hero Alexander the Great founded Alexandria in 332 BCE. Excavations have shown that glass factories sited in that town produced plain and ribbed bowls in green, blue and brown glass.
The Greek Hellenistic Age (323BC – 30BC) provided much needed impetus to the glass industry with an emphasis on man made shapes, such as pillar-moulded bowls, which were very much esteemed in the west. The technique of making these was intricate, requiring a number of processes to achieve the end result.
Following the production of the core, which was made of mud tempered with grass and coated with ground limestone, a rod was attached so it could be dipped into a vat of molten glass.
Trails of coloured glass were applied to the surface, which was then reheated and rolled smooth. The rod and core were removed and the neck and base added. It all took time, which restricted the scale of production.
The legends of glass become caught up in those surrounding the mysterious death of Alexander the Great, who died poetically at sunset on June 10, in the year we today know as 323 BC.
He was only 32 years old. His body was reputedly on view for centuries in a translucent sarcophagus in what was the most renowned and respected shrine in the Roman Empire.
We know that his body was the object of veneration by Julius Caesar, Queen Cleopatra and Roman Emperors Augustus, Caligula, Hadrian, Severus and Caracalla as well as a host of luminaries as records support that fact.
The tomb of Alexander seemingly stood within a sacred precinct the size of a large town at the heart of the greatest Greek city in the world.
Yet at the end of the 4th century AD, when the Christian emperor Theodosius outlawed paganism the tomb and its contents disappeared without trace, creating the greatest archaeological enigma of the ancient world.
What became of the tomb of Alexander the Great? Does any part of it still survive? Was his sarcophagus made of glass, natural crystal or translucent alabaster? Or, did it exist at all?
Every morning, a well-to-do Roman lady of the first century would have bathed and had her make up applied by her maids before visiting, or being visited by her friends.
The favourite scents of the day were all toilet waters, prepared with French lavender, saffron, and crushed rose petals: in the evening, heavier perfumes based on cinnamon and myrrh might be worn. The perfumes retained the properties of their fragrance because they were stored in brilliantly coloured glass vessels to protect the fragrances from light.
Changing the colour of glass at this time was a bit like cooking: everyone could follow the recipe by adding different metal oxides to sand, soda and lime, the basic ingredients for glass, creating different colours.
For example: green and aqua glasses usually have iron added, while amber and adding small amounts of iron and sulphur produces brown colours. Light blues require copper; dark blues small quantities of cobalt. Amethyst contains manganese, while opaque white contains either tin, or calcium. Selenium is just one metal oxide used to produce reddish colours.
Some reds and pinks also require the addition of fragments of gold. Superb glass vessels made by the core method were used for perfumes and medicament’s. Roman Physician Scribonius Largus (active about A.D. 50) insisted certain medical preparations should only be kept in glass containers. A more specialized subgroup of mould-made glass made by the Romans were Mosaics, used to create fabulous images on both floors and walls
In ancient times molten glass was kept in a liquid state using a wood-burning furnace. It takes a lot of wood to heat a furnace to over 1000 degrees and to put it into a contemporary context – if we only used timber to build a two story house that is about the same amount required to heat a wood fueled furnace for just one run of glass in ancient times.
If you imagine how much glass was being made throughout the Roman Empire it is easy to see how and why the natural wood supplies would become exhausted quickly turning once viable land to desert.
Glassmakers were forced to migrate constantly to other districts once they had exhausted the wood in the surrounding forest. So glass making was not an environmentally friendly process and the constant movement is more than likely why evidence of glass making is more difficult to obtain. Vessels and ovens for making molten glass were dismounted often and moved as well.
The skilled workers at Alexandria produced colourless glass, the last and most difficult, at first, to achieve, as well as gold-leaf glass; gold beaten out to a very thin sheet and sandwiched between layers of protective clear glass. It was when colourless glass was invented (through the introduction of manganese oxide) in Alexandria around AD 100 that the Romans first began to see its application for architectural purposes.
Glass windows, albeit with poor optical qualities, began to appear in the most important buildings in Rome and the most luxurious villas of the Roman patricians in Campagna. Glass windowpanes have been found at Pompeii and Herculaneum as they were coming into wider use when Vesuvius erupted and buried the town in 79ACE.
Roman stoic philosopher; statesman and tragedian Lucius Annaeus Seneca, called The Younger, (died ca. A.D. 65) maintained that fruit appeared more beautiful in a glass vessel. In a still life from the House of Julia Felix at Pompeii pride of place is given to a delightful crystal bowl, which receives most of the light. It overflows with luscious and ripe Campania fruit, including grapes, the staple crop of Pompeii’s economy.
The historical event that gave Roman glass workers the opportunity to exploit an exciting and rapidly emerging technology was the victory over Mark Anthony by Julius Caesar’s nineteen-year-old great-nephew, Gaius Octavius Thurinus, known as Octavian, at the Battle of Actium in 31 B.C and its aftermath.
It was not a massive battle between huge fleets; in fact, it was a rather small one. However it did effectively end the difficulties in governing the republic following Caesar’s murder.
During the reign of Emperor Augustus (Octavian 31BC – 14ACE) Rome emerged as an economically successful city with a population approaching one million. Augustus conquered Alexandria in Egypt on the 1st August 30BCE and the glass factories all became Roman.
Roman glass makers decorated their glass by almost every method known, including engraving it with a sharp instrument. This is a technique with Egyptian antecedents as far back as fourteen centuries B.C and it was during this time that glass became an integral aspect of the economic, social, and cultural life of the Roman world.
Glassblowing provided a solution to many problems. Shaping a mass of molten glass by attaching it to a blow pipe and inflating it was faster than casting. Glass blowers soon realized that the biggest limitation on the size of any object they could produce was the strength of their arms.
Since the first century B.C., glass makers have used the same tools to model, manipulate and decorate molten glass.
The blowpipe is an iron or steel tube, usually about five feet long, for blowing a parison, or gather, of molten glass.
Moulds are then used to impress decorative patterns on the parison.
The pontil is a solid metal rod that is applied to the base of a vessel to hold it after it is cut off from the blowpipe. It became a common tool from the seventh and eighth centuries.
The pontil leaves an irregular ring-shaped mark on the base commonly known as a pontil mark.
Blowing glass made large-scale glass production much more practicable and available to an ever expanding market. Thousands of bottles to hold oil, wine, and other liquids, were made, often square in shape so they could be packed together conveniently without wasting space.
The Romans’ ambivalence about glass is neatly summed up in the playwright Petronius’ Satyricon, in which Trimalchio the quintessential parvenu, remarks to his guests at dinner.
“You will excuse me for what I am about to say: I prefer glass vessels. Certainly, they don’t smell and if they weren’t so fragile, I would prefer them to gold. These days, however, they are cheap.”
Trimalcho (c.27-66 ACE) was the advisor of luxury and extravagance to the Emperor Nero. He personally lived a life of excess and pleasure, and reputedly like a bat, because he was largely nocturnal.
At his absurdly lavish banquet Trimalchio served rare, vintage wines in glass amphorae. Meanwhile, in the kitchen, various foods and condiments, such as garum, a popular fish sauce, were being stored in glass bottles and jars.
He wrote The Satyricon a vast satire, the longest extant part of which describes a private banqueting party of this former slave. It was held in his house in Campania with seemingly no expense spared.
Trimalcho could distinguish himself when appointed to positions of responsibility, but made many political enemies. He was finally forced by Nero to commit an elaborate suicide rather than face execution. Although it seems he had the last laugh when he lampooned Nero in his will.
Lucius Junius Moderatus Columella wrote the important surviving Latin agricultural treatise De Re Rustica, in which he recommended glass jars for preserving pickles.
Glass containers not only preserved flavour, but also had the advantage (in a society with a high level of illiteracy) of allowing one to see the contents without removing the cover.
So, glass was used at all stages in the preparation and consumption of food for serving food, drinking, and for washing hands between courses.
Roman elegiac poet Sextus Propertius (died ca. 2 B.C. ) reported that glass services were used instead of metal ones for drinking or dining in summer.
Very elegant and valuable pieces of glass made their way safely across hundreds of miles to all the outposts of the Empire, including Britannia, and despite their high value, many were consigned to the after world after burial.
Much Roman glass has been found in Britain and the so-called Lycurgus Cup in the British Museum is quite unique.
By transmitted light the vase changes colour; the green turns to a wine colour and the yellower areas to amethyst purple.
The Lycurgus Cup dates to the fourth century and the gilded bronze base and rim were added in more recent times. A frieze showing the myth of King Lycurgus being dragged into the underworld by Ambrosia, who has been turned into a vine, surrounds the cup. The frieze stands out from the body of the cup, connected to it only by small shanks or bridges.
It belongs to a type of Roman glasses called cage cups. Their elaborate design and fragile nature ensured that only a few survived intact. The main body was normally colourless and a cage effect created so the final effect was that of an inner vessel sitting within a network of glass threads that stood proud of the surface.
To find out what caused the colours of the Lycurgus Cup it was examined by a transmission electron microscope; the glass was seen to contain tiny crystals of metal about 70 nanometres across (a nanometre is a millionth of a millimetre). X-ray analysis showed the crystals consist of about seven parts silver to three parts gold.
The crystals scatter the light, rather in the same way fine particles in the atmosphere cause the ‘red sky at night’ effect.
The Romans became particularly adept at cutting glass, and they made vessels from two layers of glass, usually dark blue and white melded together. What is known as the Cameo technique was then produced by cutting through the white layer to provide an image in relief against the dark ground beneath. This was the most refined and revered of all the techniques the Romans developed and cameos were produced from other materials like sardonyx.
The most famous of all the cut glass Roman vessels ever found displaying the cameo technique is the Barberini, or so called Portland Vase, now in the British Museum at London.
Originally this stunning vessel was made by workers at Alexandria. On the bottom there is a bust of a young man in a Phrygian fisherman’s cap, thought to have been added at a later date. The vase was found in an ancient marble sarcophagus excavated at Monte del Grano near Rome in the pontificate of Urban VIII (1623-44) and placed in the palace of the Barberini family.
It was sold c.1782 and passed through several hands until acquired by England’s Duke of Portland, who in 1810 lent it to the British Museum on permanent loan. In 1845 the famous vase was completely shattered when a visitor dashed it to the floor, breaking it into over one hundred and fifty pieces.
All the fragments were gathered and it has been restored on several occasions since. Each time a small number of minute slivers remained, one of which was used to obtain an analysis with a scanning electron microscope.
Modern analysis revealed that the body of the vase was made from a soda-lime-silica type of glass. The dark blue of the background is caused by minute amounts (about one tenth of one per cent) of the colouring metal cobalt, which was added to the glass by the craftsmen.
The mythological scene on the vase probably represents Peleus and Thetis accompanied by Poseidon on one side and Aphrodite, goddess of Love on the other.
The white glass was engraved probably by using diamond, the hardest natural substance known in Roman times. It was used to cut gemstones and to produce the glorious cameo effect.
The Portland Vase was again taken apart and restored again, this time using all its fragments in 1989 . By scanning each fragment a modern computer system was able to work out where each one of them fitted. Reassembly of the vase was made difficult as the edges of some fragments were found to have been filed down during previous restorations.
Nevertheless, all the fragments were eventually replaced except for a few minute splinters. Any areas still missing were gap-filled with a blue-coloured epoxy resin or, where loss occurred to the figures, with white-coloured resin.
This now newly restored and conserved Portland Vase was returned to display again and, except for light cleaning it should not require major conservation work for many years to come. And so the great jigsaw puzzle has finally been put to rest, over 150 years after all the damage. The wonders of modern technology.
Glass from Egyptian or Roman times is often seen today as far more ornate and complex than the subsequent medieval glassware made throughout Europe. Basically, the art of glass making was not really lost following the decline of the Roman Empire but for a thousand years it did remain limited.
There are some beautiful blue drinking horns of blue glass surviving from the Medieval period of north western Europe…and throughout the Middle Ages small glass-factories continued to work, some of them deep in forests, which supplied the timber needed for their furnaces.
Carolyn McDowall, The Culture Concept Circle 2011 – 2013