Antonio Neri Reveals the Secrets of Glassmaking and Helps Make High Quality Glass Available to the World

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Antonio Neri Reveals the Secrets of Glassmaking and Helps Make High Quality Glass Available to the World


The second oldest of all manmade materials (after bronze) is glass, which for thousands of years has served important building, decorative, and utilitarian purposes. Because of its value, glass became a prized possession of the wealthy and powerful. By the 1600s the world's finest glasses were produced in Venice, Italy, whose leaders sought to protect their dominance by imposing a strict ban on the sharing of knowledge about glassmaking methods and techniques. In 1612 a Florentine priest and chemist, Antonio Neri (1576-1614) published a book, L'artra vetraria (The art of glass) that revealed the glassmaker's secrets. Making those secrets available to the public not only made possible the duplication of Venetian glassmaking, but also provided a basis for further innovation, hastening improvements in glassmaking and spurring the shift in glassmaking from artisan's craft to mass-manufactured material.


Among the most important of the advances in the material sciences, the invention of glass, and the development of techniques for manufacturing it, go back at least as far as Egypt in 3000 b.c. Indeed, the only older manmade substance is bronze. Naturally occurring glass, also known as obsidian, the product of volcanoes, was used as a tool by early humans long before the emergence of social organizations resembling ancient civilization.

It was with the Egyptians, though, that the actual manufacture of glass was first undertaken, with glass beads produced between approximately 3000 and 2500 b.c. Within a thousand years the art of glass manufacture had progressed to the point where the Egyptians were producing small glass containers, although many of these were carved or ground from glass blocks, rather than being molded or shaped into finished form during the glass-manufacturing process. Another early method of forming glass into desired shapes involved forming glass around clay or metal molds.

That process itself is both simple and complex. At it simplest, glass is the product of applying high heat to a mixture of silica (sand), soda (generally wood-or plant-ash), and limestone. These ingredients—along with smaller amounts of other materials that yield different qualities to the glass—are heated at temperatures of approximately 1500°C. The ingredients melt and combine; when cooled the resultant material is glass.

The complexity enters the formula through the various additional ingredients that can be used to alter the qualities of the finished glass. The addition of lead, for example, was found to increase the clarity of the finished glass. Variances in the amount of silica also produced differences in the finished quality of the glass, as did alterations in the amount of heat applied to the mix of materials. Of particular importance to the development of glass manufacture was the development, by at least 2500 years b.c., of simple but effective furnaces that allowed for greater control of heat, resulting in a more pure final product.

The most dramatic early refinement in glass manufacture occurred around a.d. 1 with the Roman development of a hollow iron pipe used for blowing glass—using blown air to create desired glass shapes and consistencies from the molten glass adhering to the far end of the pipe. The Romans also made large advances in etching, coloring, molding, cutting, and engraving glass.

Between a.d. 200 and 1200 the fundamental nature of glassmaking changed little—refinements in furnaces and in methods for adding color to glass were among the few innovations in the process. Despite that stagnation in further development, glass-making remained an important undertaking, and by the thirteenth century had spread throughout Europe, with Venice becoming the acknowledged center of both the glassmaking art and industry.

That centrality resulted in great wealth and influence for Venice. As a result, Venice's governing body, the Grand Council, relocated all glassmaking enterprises to the island of Murano in an effort to keep secret the mastery of glassmaking and related technologies. Any who violated the code of secrecy faced penalties including execution.

Protectiveness about glassmaking techniques was nothing new. The Mesopotamians, more than 3,000 years ago, identified their instructions for glassmaking as secret. Yet the value of glass and the public's desire for the material resulted in almost constant attempts to wrest the secrets away from those who controlled them.

One who knew the secrets was Italian priest and chemist (and alchemist) Antonio Neri. A citizen of Florence, Neri was the son of a physician. From an early age Neri applied himself to the study of glassmaking, and by 1612 had introduced at least one major innovation. This was the addition of a minute amount of gold to the molten mixture of glassmaking materials. Chemical reactions instigated by the gold produced a glass of a brilliant ruby color. The glass—which to this day cannot be mass-produced and is thus more of an artisan's product than an industrial one—came to be known as cranberry glass or gold ruby glass.

For all of his technical skills, it was Neri's ability—and boldness—as a writer that earned him his greatest fame. In defiance of the edict against sharing the secrets of glassmaking, Neri wrote a small book called L'arte vetraria (The art of glass) in 1612, the same year as his discovery of cranberry glass.

In L'arte, Neri presented virtually all of the body of knowledge that surrounded the manufacture of glass. He addressed the nature of furnaces, proper temperatures and melting times, mixtures of materials that resulted in different types and qualities of glass, and more.


Neri's little book created a revolution—the elements required for high level glassmaking became widely known, and the industry spread rapidly throughout Europe, where most previous glass manufacturing undertakings had failed to approach to the quality of Venetian glasses.

Neri's book hastened the decline of Venice as the world's glass capital, although Venetian domination of the industry was already threatened by the immigration of glassmakers who took their secretes with them. In 1622, for example, an English company sent six Italian glassmaking artisans to the Jamestown colony in the New World.

More importantly, by consolidating in one volume the essence of glassmaking, Neri provided all glassmakers with knowledge that had previously been restricted only to a few. In short, he made available not only an existing body of knowledge but also, and ultimately of more importance, he provided glassmakers with a foundation upon which they could build improvements. By having fundamental principles at their disposal, glassmakers were better and more easily able to experiment, refine, and improve the formulas and mixtures that were used to produce glass. Better and more diverse types of glass, both practical and decorative, were developed over the course of the 1600s. Antonio Neri had opened the windows of the world.

With the ability to make glass of high quality more widespread, more glass was produced. What had been a material restricted to the upper classes began to spread throughout society, transforming the nature of everyday life. Windows became common for all buildings, and this brought an unexpected but highly beneficial social and cultural change. Because windows allowed more light into buildings and homes than was previously common, the occupants of those structures became more aware of their surroundings, particularly of dirt and grime. Transparent windows led to cleaner homes, and increased cleanliness—hygiene—led to a general improvement in the quality of life. Neri's revolt against secrecy made a large contribution to both individual and social wellbeing.


Further Reading

Brock, William H. The Norton History of Chemistry. New York: W.W. Norton, 1993.

Mumford, Lewis. Technics and Civilization. New York: Harcourt, Brace and Company, 1934.

Sass, Stephen L. The Substance of Civilization: Materials and Human History from the Stone Age to the Age of Silicon. New York: Arcade, 1998.

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Antonio Neri Reveals the Secrets of Glassmaking and Helps Make High Quality Glass Available to the World

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