Essay: Glassmaking

There is evidence of glass making from as early as 4000 BC. Back then it was mostly used for the coating of stone beads. It was 1500 BC when the first hollow glass container was made. It was made by covering a sand core with a layer of molten glass. It was during the First Century BC that glass blowing became more common. At this time glass was high coloured due to the impurities of the raw materials that were used to make it. The first recorded colourless glass was made in First Century AD. The Romans were one of the most skilled in glass making and held most of the secrets. It wasn’t until the Roman Empire began to fall that the secrets began to leak out into Europe and the Middle East. At this time the greatest reputation for technical skill and artistic ability was held by the Venetians. A far amount of Venetian craftsmen left Italy to set up their own glassworks.

In Jarrow and Wearmouth, Britain there is evidence of glass works going back as far as 680 AD. There is also evidence of a glass industry in Weald and the forested areas of Surrey and Sussex around Chiddingford.

In the 1300’s Venetians made it illegal for glasses to be made with glass lenses in favour of the more expensive and valuable rock crystal.
1352 saw eyeglasses only being worn by the well-educated, very rich noblemen and the Italian clergy which shows how society affected the glass industry.

It was during the Renaissance that spectacles became more widely spread.

The biggest milestone in glass making was when George Ravenscroft invented lead crystal glass. He introduced lead into the raw materials used to make glass while trying to counter the effect of the clouding that sometimes took place when making glass. This new glass was softer and easier to decorate. It also had a higher infraction index which added to the beauty. It proved invaluable in the optical industry. The optical lenses, astronomical telescopes and microscopes we use today were made possible by this discovery. Our modern day glass industry only really started to develop are the repeal of the Excise Act in 1845 in Britain which relieved the high taxation rate that had been enforced. Until that time, excise duties were placed on the amount of glass melted in a glass house. This was levied repeatedly from 1745 to 1845.

In the prehistoric era a natural glass called obsidian was made by volcanic eruptions. It was valued for its rigidity by prehistoric man and was used to construct weapons and other utensils. Amulets and other decorative pieces have been found from as back as 4000BC. It was around this period that the basic mix for glass was invented. To stabilize the glass, sand was heated and along with lime was used to protect the glass from humidity.Dung and Earth were the building blocks of the first glass work. This was done around 1500 BC and had its roots in areas like Egypt and Mesopotamia. The procedure that followed was very simple. When the glass solidified the earthen core was discharged from its place and as a result an empty glass piece could be found.But these techniques were very big secrets and were extremely well guarded. As they were so expensive, only the rich could afford them at that time. Another decorative element, glass mosaics were produced by coloured poles of glass that were sliced to bring them to this form. They were transposed onto walls of grand buildings, especially churches in the Vatican. (MD Lyn, 2004)
The trace and major composition in a series of 16th century glass fragments, coming from the ruins of different 15’17th century castle sites in the neighbourhood of Ljubljana (Slovenia) was determined. They were found to have originated from archaeological sites in Ljubljana’s centre, Venice (Italy) and Antwerp (Belgium). In these centres, historic documents describe the flourishing glass making and working industry in the 16th century. Technological advancements have made ancient glass analysis accomplishable. The fusion of (EPXMA) Electron probe X-ray microanalysisand microscopic X-ray fluorescence (??-SRXRF) was applied to analyse the glass works in Antwerp and Slovenia. For Ljubljana’s glassworks, a different technique was used. This technique is known as ion beam analysis. A contrast of the main glass composition of the latter glass samples obtained by means of EPMA and the ion beam methods revealed that the differences between the two sets of data are generally smaller than 10%, except in the case of concentrations smaller than 1% w/w where typical values of 20% of relative deviation are noted. AS opposed to Antwerp, where both native and Venetian glass compositions are met, the Ljubljana and Slovenian palace glasses resemble a composition that closely resembles that of Venetian vitrumblanchum glass. ??mit, ??.,Janssens, K., Schalm, O., & Kos, M. (2004).

There are many journals and books showing evidence of glass making in the renaissance period. One book written by Patrick McCray was ‘Glassmaking in Renaissance Venice: The Fragile Craft.
The book examines the early stages of modern glass making as a technical process, as a means of social organisation, a development he claims put glass at the center of the market in moderately priced goods. (Mary J. Henninger-Voss, 2002)
The first evidence of man-made glass dates back over 4000 years to Mesopotamia where archaeologists found minute glass beads. The earliest Egyptians were expert glassmakers. They made use of metallic oxides and metals to colour glass. They produced glass using a technique known as core-forming which was extremely time consuming and labour intensive. (Banks, M., Elphinstone, N., & Hall, E. T, 1963)
The story of glass starts very dramatically wherever volcanoes are present. The eruptions emit flows of molten rock that carry obsidian, a highly opaque and dark coloured glass. This precious material was worked by ancient and prehistoric dwellings into a vast array of tools’ Pliny the Roman historiantells a legend that mirrors made from obsidian reflected not images but only shadows. Through a darkly coloured glass? In a tremendous turnaround of dimensions, contemporary glass essentially needed the advancements of small and sometimes tiny furnaces so that artists could make glass for themselves. (Hamel, G. (1998))
A swamp are found near Judea in the Syrian territory of Phoenicia is an area where the origin of glass can be traced. The Bellus River, which flows beneath Mount Carmel comes from the base of the Mountain. Its sands are made pure by the impurities of the river’s flow. At this place a ship of natron merchants was stranded. On the shore, to survive these sailors began lighting fires for many different purposes such as heating and food. As the natron got spread about the beach, the beach sand and matron got fused and as a result there were clear streams of a strange new liquid began that began to flow. This was how glass was first found.(Isidore of Seville, Etymologies XVI.16.Translation by Charles Witke.)

There are many other books and journals about glass making in the renaissance which have had a minor bearing on this essay. All have different arguments for the making of glass. Patrick McCray, Maxine Anderson, Charles Harrison and many more have all researched and written books on the works of glass making during the Renaissance. Since these books have had only minor import on this essay, they are not discussed to greater lengths.

The Art of Glass Making
The job of making glass during the Renaissance was usually spread between a few individuals who took up a specific part of the glass making like a modern day chain factory. Fire was used to melt sand until it was possible to shape and turn it into different objects.
The Beginning of Glass Making
It was speculated that the birth place of an ancient type of glass was discovered when Phoenician merchants travelled the coast of the Mediterranean. They would build huge, intensely blazing fires in pits dug out of the silica rich sand. This form of glass was not transparent but dark and stony looking much like clay. Until this time molten glass was only used to coat other materials for a glazed look. It wasn’t until the Venetians that glass was used to make hollow pots.
When they began to make hollow objects they came across the problem of the glass being a dirty or cloudy colour. This meant that there was a lot of experimenting and trial and error.
Beyond Venice: 1500-1750
During the Renaissance Europe was determined to copy the Venetian glassmaking styles and techniques. The glass was called ‘cristallo’. This was because it was clear and colourless. The Venetians achieved this as early as 1440. They did this by making the glass from quartz pebbles instead of the ordinary sand that was full of impurities. Cristallo was usually very thin compared to most of the thick glass that was being used that had a yellow or greenish colour. As they learned more about glass they learned to decorate their pieces with fine filigrees and coloured glass canes. They were also the first to engrave with diamond points since the Romans. Enamels, gold, metal stamps and moulds were also used. The Venetians used all of this knowledge to assemble all the elements into elegant and elaborate pieces of glass. Dragon stem goblets were one of the most popular pieces made. There are still pieces of the glass made by the Venetians in the Corning Museum of Glass. These pieces incorporate up to 12 pieces in a single object.
The objects made were treated like art by the customers who brought them. Some items were accumulated into large collections by wealthy customers.
Because of Venice’s large fleet of ships the Venetians were able to identify and obtain new pure ingredients like plant ash from Syria and Egypt. Suppliers were bound by long term contracts to keep a steady supply for themselves and also to frustrate rivals.
The problem with finding new materials was that not every material gave the right affect they were looking for. Many materials left the glass looking cloudy or a dirty colour.

The 17th Century
During the 17th century there was a book published called ‘L’ArteVetraria. L’ Arte Vetraria means the art of glass. It was written by a man named Antonio Neri. Antonio had put together everything from the ways to make glass to how to actually blow glass all in one place for the first time since making glass had become known. At this time glass was beginning to be used for more scientific reasons like microscopes and telescopes. It was a change that greatly improved the scientific world.
Places for making glass began to spring up in France, Germany, Spain, Sweden, England and the Netherlands although Venice held the top. These places were known as forest glass houses. The glass houses were mostly only temporary buildings but some were used for many years. They were sustained by using ingredients readily available in the forest to make the glass they produced. They burned trees to heat the furnace and in turn used the ashes to make the glass. ‘Potash’ was the name given to these ashes. Purified and combined with copper oxide they were a pale glossy green colour. Because they cut down many of the trees they used for the wood in their furnaces the land was cleared up and was later used agriculturally.
Window glass and drinking vessels were the items that were made the most in glasshouses. Rounded bowls and large beer vessels were the most widely made. Many items had a knob made on the side, making it better for holding, especially if the user was drunk.
Bohemian factories that had specialized in using diamond points to engrave were becoming more popular. It was said that nearly any person could do it as long as they could draw. This was when the clear glass was invented as the Bohemian makers of glass had begun to use chalk as their base ingredient when making their glass. Glass from the North parts ofEurope was in higher demand than the Venetians glass.
Fine glass was introduced to the world by Venetian glassblowers. Because of a shortage of wood it was no longer possible to use to fuel their furnaces. They had to use a different source and turned to coal. The problem with this was that they needed to come up with a way to ventilate the fumes away from the workers as well as their glass.

The Mid to Late 17th Century
In the mid-17th century English glassblowers invented what was called black glass which was really a very dark green. They used it to make strong walled vessels as it was great for long ship journeys and good for storage. Light that may damage the liquid inside was protected by the thickness of the glass. With these bottles it was easy for England to start dominating the world of distribution.
The people of Jamestown, a colony in America, began glassblowing in 1607. It was used mainly for making windows and bottles. Most of the glass was made and imported out of Germany and was hard to distribute in America. The first man to successfully distribute glass in America was called Caspar Wistar. Henry Stiegalthen followed and John Frederick Amelung came after him. The first two men eventually failed because Stiegal put as much money into it as he could. He even went as far as to use more money than he had at the time. The revolution was Wistar’s downfall. Managing to keep his head above water a little longer, Amelung opened a large glass factory in Maryland in the year 1784. It was also the year bifocals were invented by Benjamin Franklin. Unfortunately Amelung’s factory was also shut down. American distribution was hard but the glass industry continued to develop every decade.
It wasn’t long before there was another breakthrough in 1676. A man called George Ravenscroft developed a formula for making glass using lead. He was an English glassmaker who had lived in Venice for many years. He was secretly working in London when he developed this new form of glass. Lead glass stayed workable for a much longer period than the other types of glass. People began to make vessels without decoration because of its weight and clarity. They began to focus more on the form of the glass and how it was shaped.
The 1800’s
In the 1820’s mechanical press was introduced making the production of glass much easier and faster for those making it.
How Science and Technology Affected and Influenced Glass Making
During the Renaissance there were many factors that affected glass making. As the sciences grew the need for glass grew. For example glass was needed to make telescopes and microscopes which meant that the demand grew. Nowadays we take glass for granted but back then it was used for a lot of different objects. Its role in medieval and Renaissance science and technology was enormous. Glass vessels were used for medical diagnosis’ like urine samples which first started in the Islamic world. It then spread through Europe. Scientific experiments were mostly done using glass equipment. Assated by Martin and Macfarlane ‘almost every scientific advance needed glass at some stage’.
During the Renaissance technology made it possible to be able to begin the production of stained glass. This meant new possibilities on what glass could be used for and new ideas were being thought up every day. Stained glass windows became very popular in noblemen’s homes and they were the envy of all their friends. Due to this the demand for glass became much higher. Also as technology improved so did the speed and quality of the glass that was being made.
How Society Affected The Making Of Glass
Society had a big influence in most things during the Renaissance much like it does today. Many of the people who purchased glass during the Renaissance were people of the high Society like noblemen. This meant that they were often competing with their friends and acquaintances to ensure they had the envy of everyone else. This meant that they had to have the most expensive and beautiful pieces. This meant that the demand for glass was growing and as the technology of glass making grew it meant that the demand grew even more. When people saw what could be accomplished it had them demanding bigger and better pieces. Glass houses had to keep up with demand and were forced to create new objects. They had to go bigger and better than ever before.
The Issues Faced
Like the manufacture of any product the manufacture of glass had many issues with science, technology, and socio-cultural factors. The issues with making glass weren’t just with finding the right materials. When the demand for glass grew in the science industry the glass industry had to face the problem of manufacturing glass more quickly.
During the renaissance which means ‘rebirth’ the manufacture of glass had to be reborn too. The manufacturers had to begin to think of other materials and ways to make glass.
New technologies enhanced the speed of making glass but they also meant new issues for the manufacturers. These were issues like keeping the technology in working order as well as finding new ways to melt their ingredients quickly.
Over the years they went from using Obsidian to Chalk and through every other material they could think of. The issues with testing new materials meant that there were always issues with things going wrong and them not getting the right end result. It took a long time before they finally came to find the right materials for the job. This only happened through trial and error making it a very time consuming period.
The introduction of new technologies both helped and hindered the making of glass. It took a long time to understand what temperature the materials needed to melt but with new technology it became easier to judge. New technologies also helped with removing impurities and gaining only the purest materials for the glass itself. It also meant that they were able to try new decorations and make even more elaborate and elegant pieces which drew more attention to their work and in turn grew a higher demand.
Eventually the demand grew so much that they had to come up with new technologies to be able to keep up the speed of the glass they were making. It wasn’t until the modern day that this was perfected into the factories and facilities there are today. The factories we use nowadays are much different from the glass houses of the forest that were once used in the Renaissance but it does us well to sometimes think back on that time and really appreciate how far we have come.
Ever since glass making began there have been many ups and downs. From the start there were problems with the colour and what materials could be used. There were the influences of people from outside the glass making industry who determined what was made and what wasn’t. The technology available throughout the centuries also influenced the making of glass. When taking all these elements and putting them together it is hard to believe that glass makers didn’t just give up. The determination and persistence of glass makers in the past, especially the Renaissance has made the glass industry what it is today. Without the discovery of the materials that made clear glass we would not have windows, drinking glasses and so much more the way we have them today. The things that influenced the making of glass in the Renaissance still really affect the glass industry today without us really even knowing it. Today glass is taken for granted. Unlike when it was first discovered we now walk past a glass window or pick up a wine glass without even thinking about its beauty or really even thinking of how it may have been made. At one time glass making was a very high art form but is now taken for granted in today’s world.

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