Welcome to the new Original Bristol Blue Glass website. The same fantastic products and service, but with a fresh new look!

A Brief History of Glassmaking

A brief history of glassmaking

Exactly how and when glassmaking came to be is unknown.

It is had generally been accepted by experts until recently that glassmaking was first discovered in Mesopotamia more than 3,500 years ago but the extent of the abilities of these peoples and the frequency with which they made glass is a mystery.

Various stories and myths have been laid out throughout time surrounding the origins of glassmaking, most notably by Pliny, the famous Roman historian. He posited that the method for making glass was stumbled across by Phoenician sailors while they were cooking meat over a crude fire on a beach in what is now modern-day Israel. While this makes for a romantic tale, it cannot be completely true as fires used for cooking do not even nearly reach the necessary temperatures for sand to become molten.

Though obviously not founded entirely in fact, it is recognised by scholars that this area of the world, specifically the beaches of Ptolemais, are known to have been a centre for glassmaking, so Pliny was probably not completely wrong.

It was widely believed until more recent years that glassmaking was first carried out in Mesopotamia several thousands of years ago, due to artefacts uncovered about 100 years ago in Iraq. This same theory suggested that it was the Egyptians who ‘borrowed’ the technique of the Mesopotamian people. However, evidence has now been uncovered that suggests it could in fact be the other way around and that it was the Egyptians who discovered the technique and that the people of Mesopotamia ‘knowingly copied’ Egyptian designs.

Exactly who can claim the glory may never be fully known and is perhaps unimportant anyway, but what can be said is that the methods are thought to be very similar. The glass objects originally produced with these methods were simple beads. It is speculated that they were used as substitutes for precious stones and were used as decorative items. However, this is simply conjecture and it is just as possible that these beads are the accidental by-products of metalworking or occurred during the creation of faience, an ancient process similar to ceramic pottery but with attributes of glass.

We believe that it was the Ancient Egyptians who furthered the art of glassmaking sometime around 1500BC. Small glass articles rather than simple amulets or pebbles have been found from this period in Egypt and Syria that show a clear level of improvement.

However, we still know very little about the process of making glass in this time other than that the glass was worked while cold and shows signs of a technique similar to that of stone workers of the time. Almost 1000 years go by between this time and the making of the first manual of glass making which was found in the Assyrian Assurbanipal’s library although even at this time, the method is still very distant to that of the more recent invention of blowing glass. Though the production of glass vessels is known to have occurred sometime around 500BC on the Italian Peninsula at the start of the Roman Republic, it wasn’t until half a millennium later that the technique of blowing glass was invented by the Phoenicians.

Glass blowing was until as recent as the early 1900s a completely manual task. Essentially, molten glass is gathered onto a long hollow tube that is first given a basic shape and then blown, in a similar way to a balloon through the hollow pipe. The hollow tube is then rolled back and forth across the arm of a glass workers chair to ensure a spherical shape. Next, depending on what is being made, various tools are used to give shape or a ‘neck’ in the case of a glass or vase. It is a long process that cannot be rushed as doing so can make the molten glass impossible to work with. To ensure the material stays at a workable temperature, it can be reheated, but the object being created must be blown and then rolled out several times. Of course, this process was developed and improved upon throughout the years, but during the early days when it was first invented, some time around 50BC, the secrets of glass blowing were heavily guarded. The method is said to have been passed down the generations for thousands of years and those with the knowledge were able to command a handsome reward as glassware was, for many thousands of years, a luxury that could only be afforded by the wealthy. Phoenician glassblowers were literally held hostage and forbidden from travelling for fear that the process would be leaked, however, some escaped their captivity and eventually the art spread into present day Switzerland, France and Belgium. Venetian glassblowers were also prohibited from leaving the island of Murano, indeed to do so was a crime punishable by death.

Though the technique of glassblowing eventually spread, its development slowed somewhat following the decline of the Roman Empire in 5AD and led to a fall in demand for ornate pieces. Despite not being affordable to the general public, glassmaking had been strongly encouraged by the Roman government and several large-scale centres of manufacturing were set up. Artefacts have been uncovered from Cologne, known to be one of the largest glassmaking centres of the Roman period, that suggest a method involving stone and terracotta moulds where glass would be blown in through a hollow tube into the mould. However, these types of findings are rare and without the driving force that was the Roman Empire, a large gap formed in the development and production of glass. Though the glass industry later received an injection of life during the Renaissance period, knowledge of the process stayed guarded and highly secretive and as a result, the finished articles remained the reserve of the wealthy for many years.

In the early years of 1200AD, The Venetian Glassmakers Guild was established after many years of production in the area. Venice played an important role in the development of glass over the years and many different craftsmen came here at different points in time. Much of this came from the island of Murano, located just off the coast of Venice and after a series of fires involving the glass workshops, in 1291AD, all Venetian glassmakers were forced to live and work on the island. This aimed to prevent future fires spreading to the city of Venice, but it also made it easier to restrict the sharing of the important and valuable glassmaking secrets. Though knowledge of the process had already spread to other countries, improvements and specialisations continued to be made by these glassmakers, for example, glass mirrors and crystals. This furthered the renown of these great glassworkers and Venetian glass is still celebrated to this day for its originality and quality.

Fast forward to the 17th century and at this point although glass was in production by many different people in many different locations around the world, when Antonio Neri released his book ‘L’arte Vetraria’ (in English, The Art of Glass) it revealed the secrets of glass and glass making with the world. This allowed for a boom in production and an improvement in the methods of many to be found. In France for example, production of plate glass began that allowed mirrors to be produced in larger quantities than before. It also allowed for more notable advances in England when in 1676 an English chemist named George Ravenscroft invented lead glass (also known as crystal glass or flint glass)

This invention was a significant breakthrough for a number of reasons. First of all, the addition of lead to the glassmaking process created a more brilliant finish that was also harder. As a result of this increased hardness, it could be engraved to produce sharp images and designs, something that was not possible before this. Importantly though, this discovery paved the way for the creation of coloured glass by way of adding different elements. This not only served to enable glassmakers to create more beautiful and striking pieces but allowed for certain types of bottles and containers to be fabricated solving problems along the way. It was found that adding gold to the molten mix of glass created the beautiful but expensive ruby coloured glass, whereas small amounts of cobalt oxide produce the much sought after cobalt glass, commonly known as Bristol Blue. These additional elements do not actually add colour per se, rather they alter the pattern of light as it passes through the glass and block certain colours in the spectrum. As mentioned, this not only allowed the creation of more striking pieces of glasswork, but the addition of Nickel, depending on the concentration, was found to create dark green or ‘black glass’. This proved to be an important discovery and allowed for the creation of bottles and containers that could block out light which allowed for liquids to be preserved for much longer durations of time. This discovery thrust England ahead of the competition and it became the world’s leading bottle manufacturer and distributor.

During the colonisation of North America by the British, glassblowing was taken to America in the early 1600s, which in the years to come helped some of the most important developments to come about. Possibly one of the most well-known inventions involving glass by an American is Benjamin Franklin’s discovery of bifocal eyeglasses. Franklin suffered with presbyopia, or near sightedness which is now known to be a common ailment as our eyes age. Using an eyeglass with two distinct focal ranges, he reportedly said in a letter to a friend that using his new invention of ‘double spectacles’, his eyes were again as useful to him as they ever were. Of course, over the years the field of optometry has developed and improved as new glass has become available, but Franklin’s addition to the history of glass and glassmaking is undeniably extremely important.

Shortly after the invention of bifocal eyeglasses, another advancement came about that while not as dramatic in itself, allowed for very important after effects. In the 1820s, the mechanical press was invented that made glass production easier and cheaper than ever before. Within two decades, glass became commonly available and used as a normal household ware. Glasses, flower vases and dishes are no longer just for the wealthy. More importantly than this though, the process for making glass was easier and cheaper and with the fairly recent introduction of the lightbulb, demand for glass was at an all time high. Child labour had become a problem in glass making locations around the world but in 1903 when Michael Owens, a New York based inventor developed the automatic bottle blowing machine, it was about to come to an end within the glassmaking world. Not only did child labour end in the industry, but production of glass was both increased while costs were cut by 80%. As many as 180,00 bottles could be manufactured per day, per machine and millions of light bulbs began being produced every day throughout the country.

In recent years, improvements continue to be made. While the same basic methods of floating molten glass on a metal sheet and blowing molten glass through a hollow tube are still employed in a sense, machines have streamlined and improved the process while cutting production costs to a fraction of previous levels. Possibilities and quality have also increased, and ever more ingenious and beautiful designs are made.

In addition to the technical improvements that continue to abound us due to technological advancements, the studio glass movement that began in the 1960s continues to give modern glass artists and glass workers the ability to work in their own studios. Often these individuals choose to use old fashioned techniques to produce hand made and unique items but many also decide to experiment with new and different methods for producing glass. What is certain is that the history of glass making will continue to evolve. New methods will be discovered and old ways will be improved upon to increase possibilities and give us ever more beautiful glass designs.