Murano Glass and Glassmaking Techniques

Since ancient times, glass has held a mesmerizing, almost magical, fascination for people.

Reflecting and refracting light and color, glass in its many forms has been used for functional purposes such as vessels and stemware, but also for decoration, celebration and religious ceremonies.

Believed to have originated in ancient Egypt, glassmaking was further developed during the Roman Empire, and began to take hold in the Republic of Venice nearly a thousand years ago.

Legendary for its long tradition of glassmaking, Murano, Italy may be one of the most well recognized glassmaking centers in the world.

History of Murano Glass

Glassmaking began in the city of Venice as early as the 5th century AD, when a Benedict Monk named Dominic wrote of glass phials (shallow vessels) being produced. The small group of islands known as Murano, just off the coast of Venice, was primarily used as a commercial port from as early as the 7th century.

In 1291, purportedly fearing fires caused by the glass furnaces, the Republic of Venice banned them from the city. Thus, the glassmaking foundries were relocated to the Island of Murano, where the artisans, though given special social and legal privileges, became virtually prisoners.

In 1295 an edict was declared, essentially dictating that glassmakers could not leave Murano on threat of bodily harm, since the Venetian government desired to keep the trade secrets of this vital industry from spreading to other glassmakers in Europe. This enabled the craft and glassmaking knowledge to be passed down from one generation to the next in Murano for centuries.

Murano’s Prominence in Glassmaking

Known for its exquisite beauty, craftsmanship and utilitarian design, Murano quickly gained almost a monopoly on the production of fine glass in Europe and provided a major source of trade income and profits for the Republic of Venice.

Mirrors produced in Murano were intricately detailed and ornately decorated. Glass blowing techniques flourished. In time, glass jewelry making also became part of the Murano glassmaking tradition and many new glassmaking techniques were developed.

By the 14th century the glassmakers of Murano the island’s most prominent citizens, enjoying immunity from prosecution by the state, allowed to wear swords, and their daughters often marrying into the most affluent families of Venice.

However, since the glassmakers were prevented from leaving the Republic, many of the artisans became disenchanted and began leaving the island, taking great risk to establish foundries in other Italian cities and even in places as far flung as England, the Netherlands and Scandinavia.

By the 17th century, Murano’s prominence as a glassmaking center had begun to decline and the craft nearly vanished, due to political changes, an exodus of glassmakers from the Republic of Venice and the development of new glassmaking techniques elsewhere.

During the mid 19th century, glassmaking in Murano underwent a renaissance, in part due to the efforts of businessman Antonio Salviati, who sold glass tiles used to refurbish the many mosaics in Venice. In the 20th century, tourism helped further revitalize the industry.

Today, the glassmakers of Murano are famed for producing exquisite handcrafted art glass and jewelry that sells for amazing prices, along with mirrors, lenses and other more conventional glassware products.

Murano Glassmaking Techniques

Traditionally, most of the Murano glass was functional rather than decorative, but as the craft evolved pieces became more and more decorative with new innovations in the production of ornate mirrors, glass blowing and colored glass.

Murano glassmaking is a complex process, often involving the Lampworking technique, in which extremely high temperatures convert silica to a molten liquid state and allowed to cool slowly. Melting agents called flux, are added to the glass to help slow the solidification process. During this cooling process the glass is soft enough to be worked and shaped by the artisan.

Other raw materials are added to the glass to produce various effects; sodium to make glass surfaces opaque, nitrate and arsenic to eliminate bubbles, along with a variety of coloring and texturing materials, depending upon the desired effect.

Over the centuries, many glassmaking techniques were developed and refined in Murano, including:

• Avventuria – meaning “adventure”, which refers to the difficulty of this process, metal flecks embedded in clear glass to reflect light, using copper or other metal oxides to create a shimmery, metallic look.
• Battuto – meaning "beaten", the process is similar to inciso with deeper and broader cuts, sometimes used to create the appearance of fish scales.
• Corroso – meaning "corrosive", a glass etching surface treatment in which a finished glass piece is etched by dipping it in a vat of hydroflouric acid, with sawdust or paraffin masks used to cover desired areas from the etching process.
• Cristallo – produced a clear and malleable glass without color, which can be blown into very thin-walled vessels.
• Filigrana – technique developed in the 1500s to create pieces with an opaque white or colored glass core, using glass rods fused together, then blown and shaped by the artist. Three patterns include Mezza Filigrana (single filament rods), Reticello (diamond pattern created by twisting two halves of a glass piece in opposite directions during heating), Retortoli (two filaments twisted into a spiral shape).
• Ghiaccio Ice – hot glass submerged in cold water to finely crackle a glass surface.
• Incamiciato – multilayered colored or pasta Vitrea glass encased in an outer Cristallo transparent, colored layer.
• Inciso – meaning "incision", a grinding wheel is used to score a thin line scored into glass.
• Inclamo – many different colored glass pieces fused together, forming a single piece while the glass is pliable.
• Iridato – exposing glass to gaseous vapors of a metal such as tin or titanium to produce a thin iridescent coating.
• Lattimo – opaque white or colored glass, also called milk glass.
• Massiccio – large or heavy glass objects created without blowing because the molten glass is too heavy and dense. The glass is shaped, molded or formed while hot.
• Millefiori – meaning "a thousand flowers", one of the oldest techniques still in use, a glass object is encased in a layer of clear or tinted glass and decorated with Murrine.
• Murrine – technique developed by the Romans and revived in the late 1800s, using thin sections of glass rods, which are fused together, blown, and then formed or molded to create shapes as the artist desires desired shape, oftentimes a floral or geometric design.
• Pasta Vitrea – difficult technique to master, a colored, opaque glass is created by adding clear or colored crystals to molten glass.
• Pennelate – fusing colored pieces of glass to the surface of a hot glass object while being blown.
• Pulegoso – clear glass with lots of bubbles, or puleghe, created by adding kerosene to hot glass, which forms bubbles upon combustion.
• Smalto – enameled glass used to create tile mosaics.
• Soffiati – a mouth blown glass piece which has classic lines and subtle colors.
• Sommerso – meaning “submerged”, the sunken glass technique uses layers of glass formed by dipping the piece repeatedly in molten glass, often producing a clear outer glass surface, with multi-layered colors and hues underneath.
• Tessere – fusing various, almost random shapes and sizes of glass pieces together, then hand blowing and working the resulting piece into a final form.
• Tessuto – multicolored and often striped glass piece made by fusing together colored rods in an alternating pattern and then blowing.
• Trasparente Colorato – similar to Cristallo, but with tint or color added to the glass.
• Velato – treating the surface of a glass piece with the grinding wheel to produce a satin finish.