Glass History and Information

Glass beads have been in use for over 5,000 years, with the earliest known origins in Mesopotamia and later in Egypt. The art of glass bead-making continued to evolve and grow more complex over time. The ancient technique of "core-forming" involved dipping a metal mandrel or rod into pieces of glass over a flame, and then cutting the resulting tube into meter-long pieces which were further cut into tiny glass beads. The glass was made using just three components: sand quartz, soda ash, and limestone.

In Europe, glass bead-making can be traced back to the 1st century BCE in Bavaria, and the Romans traded glass beads throughout their Empire between 100 BCE and 400 CE. Vikings in Scandinavia produced glass beads, including millefiori, between the 8th and 11th centuries. While glassmaking was a well-established craft in the Middle East, it was not until the capture of Constantinople by the Crusaders in 1204 that Islamic glassmaking techniques were introduced to Venice. Venetian glassmakers adapted and developed these techniques alongside their own, resulting in unique outcomes.

By the late 15th century, glass beads were in high demand, and Venetian glassmakers developed techniques for mass-producing seed beads. Their glassmaking methods were closely guarded secrets, with harsh punishments for those who revealed them. Due to increased demand, Venetians sent uncut glass tubes to be cut and polished in Jablonec, Bohemia, where natural resources such as quartz and potash were readily available.

In recent times, the production of glass beads has shifted to Japan, India, and China due to increased production costs. The Czech Republic is the only European country with a strong market presence. However, some Venetian and Murano glassmakers have found a niche in the high-end market. Glass seed beads have had a significant impact on cultures worldwide, serving both functional and decorative purposes. They have represented wealth, power, spirituality, and currency, opening doors for global trade expansion.

Although glass is commonly used in modern times for a wide range of applications such as kitchen utensils, ornamental objects, windows, and communication technology, it was initially a highly valued and sought-after material in prehistoric times. The earliest ancestors used naturally occurring glass (volcanic obsidian) as a weapon and useful tool. The first evidence of glass production comes from Ancient Egypt and Mesopotamia, where glass products were created by glazing premade objects or accidentally forming beads during metalwork processes. Glassmaking evolved into a more organized profession during the late Bronze Age, but it was a slow and unreliable process that did not enable glass to become commonplace.

The turning point in the history of glass manufacture came in the 1st century BC when Syrian and Palestinian workers discovered the art of glass blowing, which transformed the industry into a cheap and easily produced material. The Romans used glass extensively, not only for containers and jewelry but also in architectural purposes, especially after Alexandrian workers discovered the secret of making clear glass. Glass production today still follows a similar process, with sand heated to extreme temperatures and then shaped into almost any form through blowing or pouring into pre-designed molds. This simple process can be enriched with additives to provide glass with various colors, opacities, and other properties.

There are several techniques used in modern glass production, including glass containers, float glass processes for flat windows, and manual glass blowing for art objects and custom containers. After manufacture, glass products can be treated with coatings, heat treatments, engraving, or other decorations.

Throughout history, humans have developed the technology to create glass, with ancient civilizations in Egypt, Rome, and Persia perfecting the recipe and ingredients still used today. The main component of glass is pure silica, which can be found in sand. However, because pure silica has a high melting temperature and is not the most durable material, additional substances have been introduced into glass recipes to strengthen it and change its properties.

Modern glass consists of:

Pure silica (SiO2, fused quartz) makes up 70-74% of modern glass. In ancient times, glassworkers used recipes with more than 90% pure silica, but chemists have found ways to lower the melting point by introducing various additives, most notably sodium carbonate. Pure silica glass has the ability to block UV radiation, which modern glass cannot do.

Sodium carbonate (Na2CO3) is an important ingredient in modern glass as it lowers the melting point of silica to a more manageable 1200°C. However, it also makes the glass water-soluble.

Lime (calcium oxide, CaO), magnesium oxide (MgO), and aluminum oxide (Al2O3) are added to prevent glass from being water-soluble and to increase its chemical structure. Glass enriched with lime makes up over 90% of the glass used today.

Lead oxide, barium, and lanthanum oxide can increase the glass's refractive index, making it more reflective and suitable for optical purposes such as eyeglasses and lenses. Thorium oxide was used for a similar purpose in the past, but it was phased out due to its radioactivity.

Sodium sulfate, sodium chloride, or antimony oxide can be added to prevent air bubbles in the glass mixture.

While modern technology has allowed for larger quantities of glass to be produced, the basic components and recipe for glass have remained largely unchanged since ancient times. Glass production involves heating sand to extreme temperatures and then shaping it into various forms through blowing or pouring into molds. Glass products can also undergo additional treatments such as coating, heat treating, engraving, or decoration.

Bibliography

• The History of Beads by Lois Sherr Dubin
• Perle e Impiraperle (un lavora di donne a Venezia tra 800-900) Arsenale Editrice 
• Collective Beads by Robert K. Liu I
• Perle Veneziane by Consorzio Venezia Perle (1989)
• The Book of Beads by Janet Coles, Robert Budwig
• The Complete Bead Resource Book by Patricia Abahusay
• The History of Lampworking by Robert A. Mickelsen
• Coles, J. and R. Budwig. 1990. The Book of Beads. New York: Simon and Schuster