Venetian Glass (vetro veneziano), has been made for over 1,500 years and since the 13th C, production has been concentrated on the island of Murano. It has a long history of innovations in glass making being Europe’s first major glass making centre; but is today renowned for its artistic creations.
Originally controlled by the Byzantine Empire, Venice eventually became an independent city state. The city with its strong naval and commercial prowess, became a highly successful trading port and by the 11th C dominated trade between Europe, North Africa, and the Middle East.
Many European Crusaders passed through Venice on their way to and from the Holy Land. Treasures of many kinds were bought and sold in Venice: spices, precious metals, gemstones, ivory, silks and glassware. In addition to the nobility, successful trade bred a wealthy merchant class who became patrons of art and architecture.
Trade links and the movement of skilled artisans from the Middle East helped Venetians gain additional skills; as glass making was more advanced in areas such as Syria and Egypt.
Venetian Glass making in Venice had existed since the 8th C. The earliest archaeological evidence of a glass factory in the area comes from the island of Torcello and dates from the 7th to 8th C.
However, by laws passed in 1291, glass making was then concentrated in Murano; removing the significant possibility of a major fire disaster for the city. The move also helped further developments in glass making skills and preserve secrets of their profession.
During the 15th century, Murano glass makers created an almost transparent glass named “cristallo”; considered the finest glass in the world. Another development was a white or milk coloured glass known as “lattimo”, that resembled porcelain. Later they were considered Europe’s finest makers of mirrors.
By the 15th and 16th centuries, Murano became Europe’s premier glass making centre, Venice’s dominance in Mediterranean trade created a wealthy merchant class that became connoisseurs and collectors of the arts. This helped establish demand for art glass and innovations.
As glass-making skills spread throughout Europe, the importance of Venice and its Murano glass makers declined. The fall of the Venetian Republic in 1797, caused more hardship for Murano’s glass making industry.
Murano glass making began a revival in the 1920’s and today, Murano is one of Venice’s great tourist attractions. The island is home to many competing glass factories and a few artist’s studios.
The Museo del Vetro (Glass Museum) in the Palazzo Giustinian, was founded in 1861 and contains displays on the history of glass making from Roman times to the present day.
Glass Making: Origins and History in Venice and Murano
The region between the Tigris and Euphrates rivers is considered the birthplace of glass making. Evidence suggest that glass was made there before 2000 B.C. it was also made in Syria as far back as 1700 B.C. and around 100 B.C., the Syrians started glass-blowing.
There are two main theories about the beginning of Venetian glass making.
The first is that glass making began as glass makers from Aquileia arrived after fleeing barbarian invasions during the fifth century.
The second theory is that Venetian glass making developed from Venetian interaction and trade with the Eastern Mediterranean. The original Venetian glass makers were joined by glass makers from Byzantium and from the Middle East; which enriched their glass making knowledge. Glass was made in the Middle East long before it was made in Europe, though Ancient Roman glass made in Italy, Germany and elsewhere; could be extremely sophisticated.
Early products included beads, glass for mosaics, jewellery, small mirrors, and window glass.
Venetian glass making grew in importance to the city’s economy. Around 1271, the local Guild of Glass Makers, introduced rules to help preserve glass making secrets. It was forbidden to divulge trade secrets outside of Venice. If a glass worker left the city without permission, he would be ordered to return. For failure to return; his family would be imprisoned. If he still did not return, an assassin would be sent to kill him. Additional rules specified ingredients used for making glass and the type of wood used as fuel for the furnaces.
By 1291, the law confined most of Venice’s glass making industry to the island of Murano, which is actually a cluster of islands linked by short bridges. The island is located about 1.2 kilometres north of Venice. Moving the glass making industry to Murano removed the threat of a disastrous fire in Venice. Isolation also prevented the spread of Venetian glass making expertise to potential competitors and made it easier for the government to monitor imports and exports. Glass makers leaving without government permission, or revealing trade secrets; was punishable by death.
Murano in the 13th C, was a summer resort where the aristocrats of Venice built villas with orchards and gardens. Venice to Murano took about an hour by row-boat. Although the glass makers could not leave the island, the nobles had no such constraints.
Despite their travel restrictions, the glass makers enjoyed certain benefits. They were under the direct rule of Venice’s Council of Ten and had extra privileges. In the hot summer, they did not work whilst furnace repair and maintenance was performed. They also enjoyed heightened social status. In 1376, it was announced that if a glass maker’s daughter married a nobleman, there was no forfeiture of social class, so their children were nobles.
While the Murano glass makers were typically men, records exist beginning in the 1400’s of women working in the manufacture of glass in Murano.
L to R: Cristallo Stem Glass – Filigrana Style Jar – Enamelled Lattimo Glass – Barovia Enamelled Jar – Bowl c 1970’s
Major Products and Innovations
The Venetian glass makers of Murano are known for many innovations and refinements to glass making. Among them are Murano beads, cristallo, lattimo, chandeliers, and mirrors. Additional refinements or creations are goldstone, multi-coloured glass (millefiori), and imitation gemstones made of glass. In addition to guarding their secret processes and glass recipes, Venetian and Murano glass makers strove for beauty with their products.
Aventurine, also known as goldstone glass, is translucent brownish with metallic (copper) specks. It was developed by Venetian glass makers in the early 15th century. It is first cited in historical documents in 1626. The name aventurine is used because it was discovered accidentally.
Beads, were made by the Venetians beginning in the 1200’s were used as rosary beads and jewellery. They were also popular as gifts to in Africa and native American Indians
Calcedonio is a marbled glass that looked like the semiprecious stone, chalcedony. Created during the 1400’s by Angelo Barovier, considered Murano’s greatest glass maker. He was an expert glass-blower, revived enamelling and also worked with coloured glass. His family had been involved with glass making since at least 1331 and the family continued in the business after his death in 1460.
Chandeliers. During the 1700s, Giuseppe Briati (born in Murano in 1686) was famous for his work with ornamented mirrors and chandeliers. His chandelier style was called ciocche – literally bouquet of flowers. Huge Murano chandeliers were used for interior lighting, in theatres and palaces. He learned the secrets of working with Bohemian crystal; which was becoming more popular than Murano cristallo. In 1739, the Council of Ten allowed him to move his furnace from Murano to Venice because the excellence of his work had caused such jealousy. Briati died in Venice in 1772 and is buried in Murano.
Cristallo is a soda glass, created during the 15th century by Murano’s Angelo Barovier. At the time, cristallo was considered Europe’s clearest glass, and is one of the main reasons Murano became of such importance. It looked like quartz, which was said to have magical qualities and often used in religious objects. This type of glass was fragile and difficult to cut, but it could be enamelled and engraved. Manganese was a key ingredient in the secret formula. An easy modification to cristallo made in Murano, was to produce a frosted or crackle version.
Filigrana style was developed in Murano in the 1500’s. By embedding white or coloured glass canes in colourless glass, giving the glassware has a striped appearance. Vetro a fili has straight white stripes, vetro a retortoli has twisted or spiral patterns, and vetro a reticello has two sets of lines twisted in opposite directions.
Lattimo or milk glass, began being made in Murano during the 15th century; Angelo Barovier is credited with its re-discovery and development. This glass is opaque white and was meant to resemble enamelled porcelain. It was often decorated with enamel showing sacred scenes or views of Venice.
Millefiori glass (thousand flowers), is a variation of the Murrine technique using coloured canes in clear glass and is often arranged in flower-like patterns. This technique was perfected in Alexandria, Egypt, and began being used in Murano in the 15th C.
Small Mirrors, were made in Murano beginning in the 1500’s and mirror makers had their own guild formed in 1569. Murano mirrors were known as much for their frame artwork. By the 17th C, Murano mirrors were in great demand. However, by the end of that century, English-made mirrors were considered the best quality. Only one glass house in Murano was still making mirrors by 1772.
Murrine technique begins with the layering of coloured liquid glass heated to 1,040 °C; which is then stretched into long rods called canes. These canes are cooled and then sliced in cross-sections, which reveals the layered pattern. Ercole Barovier, a descendant of Murano’s greatest glassmaker Angelo Barovier; won numerous awards during the 1940’s and 1950’s; for his innovations using this technique.
Sommerso (submerged) is a form of artistic Murano glass that has layers of contrasting colours, which are formed by dipping coloured glass into another molten glass and then blowing the combination into the desired shape. The outermost layer, is often clear. Sommerso’ was developed in Murano during the late 1930’s. Flavio Poli was renowned for using this technique and it was made popular by Seguso Vetri d’Arte and the Mandruzzato family in the 1950’s. This process is a popular technique for vases and occasionally sculptures.
Golden Age then Decline
The 16th century was the golden age for Venetian glass making in Murano. Major trading partners included the Spanish Indies, Italy, Spain, Ottoman Turkey and the German-speaking states. At least 28 glass making furnaces were in Murano in 1581. Numerous royalty, leaders and dignitaries visited Murano during this century. Collectors of Murano glass included Henry VIII of England, Pope Clement VII, King Ferdinand of Hungary, Francis I of France, and Phillip II of Spain.
Eventually, the dominance of cristallo came to an end. In 1673, English glass merchant George Ravenscroft created a clear glass he called crystalline; but it was not stable. He later improved his technique, by adding lead oxide; creating “Crystal” glass. Ravenscroft’s new glass, was less breakable than cristallo. Over the following decade Bohemian and Prussian glass makers, made a harder variation of this glass, with the addition of chalk and lime. Although not suitable for Murano style artwork, this harder and thicker glass was better for engraving and grinding.
The Bohemian and English glass eventually became more popular than cristallo made in Murano. By the 1700’s, Murano glass was traded mostly with Italian states and the Turkish empire. Small quantities were traded with England, Flanders, the Netherlands and Spain.
With Napoleon’s conquering of Venice in 1797, the Venetian Republic ended. This caused hard times for glass making in Murano and some of the Murano methods became lost. Controlled by France and Austria, Venetian glass making became unprofitable because of tariffs and taxes; glass makers that survived were reduced to making mostly beads.
Napoleon closed the Venetian glass factories in 1807, although simple glassware and beadmaking continued. However, it was not until Venice became part of Italy in 1866 that Murano glassmaking experienced a revival. Around that time, local leaders such as Abbot Vincenzo Zanetti (founder of the Murano Glass Museum), along with the Murano factory owners; began reinventing the earlier Murano techniques for making glass.
Ingredients. Murano glass from its beginning until the fall of the Venetian Republic, was mostly a very high quality soda lime glass (using today’s terminology) that typically had extra attention focused on its appearance and artistry.
Glass from that period typically contained:
65 to 70% silica (sand or quartz). Sand is a common source for silica (sourced from Crete and Sicily). For certain types of glass, the Murano glass makers used quartz (from northern Italy).
A flux, usually soda (sodium oxide, 10 to 20% of the glass composition), was added to enable the silica to melt at a lower temperature. Their source for soda was what they called allume catina; plant ash found in the eastern Mediterranean countries or from the early 16th century Spain and France.
A stabiliser, usually lime (calcium oxide, about 10 percent of the glass) was also added for durability and to prevent solubility in water.
Small quantities of other ingredients were added to the glass, mostly to affect appearance.
Process. The mixing and melting of the batch of ingredients was a two-stage process.
First stage: nearly equal amounts of silica and flux were continuously stirred in a special furnace called a calchera furnace and the mix was called fritta.
Second stage: the fritta was mixed with selected recycled waste glass (cullet) and melted in another furnace. Depending on the type and color of glass, other additives were used. Lead and tin were added for white opaque glass (lattimo). Cobalt was used for blue glass. Copper and iron were used for green and for various shades of green, blue and yellow. Manganese was used to remove colours.
Although natural gas is the furnace fuel of choice for glass making today, the fuel mandated in Murano during the 13th century was alder and willow wood. During this second stage, the surface of the molten glass was skimmed, to remove undesirable chemicals that affected the appearance of the glass. Additional techniques were used as glass making evolved. To improve clarity, molten glass was put in water and then re-melted. Another technique was to purify the flux by boiling and filtering.
The Venetian glass makers used a set of tools that changed little for hundreds of years
“Good tools are nice, but good hands are better,” is an old Murano saying, that reinforces the idea that the glass makers of Murano rely on their skills; instead of any advantage caused by special tools.
“Ferro sbuso” or “Canna da soffio”, is the blow-pipe essential for extracting molten glass and beginning the shaping process.
“Borselle”, is a tong-like tool of various sizes used to shape glass that has not hardened.
“Borselle puntata”, is a similar tool, only it has a pattern that can be imprinted on the glass.
“Pontello”, is an iron rod that holds the glass while work is done on the edge of the glass.
“Tagianti”, is a large scissors used to cut glass before it has hardened.
“Scagno”, is the workbench used by the glass maker.
Modern Murano Glass
Some of Venice’s historical glass factories in Murano remain well known brands today, including De Biasi, Gabbiani, Venini, Salviati, Barovier & Toso, Pauly, Berengo Studio, Seguso, Formia International, Simone Cenedese, Alessandro Mandruzzato, Vetreria Ducale, Estevan Rossetto 1950.
The oldest glass factory is “Antica Vetreria Fratelli Toso”, founded in 1854.
Overall, the industry has been shrinking, as demand has waned. Imitation works from Asia and Eastern Europe, take an estimated 40 to 45% of the market for Murano glass. Public tastes have changed, while the designs in Murano have largely stayed the same.
In 1994, to fight the major imitation problem, a trademark certifying authenticity was introduced. By 2012, about 50 companies were using the Artistic Glass Murano® trademark of origin.
Glass making is a highly skilled, but difficult and uncomfortable profession. Unlike 500 years ago, the are no special privileges. Today, foreign imitations and difficulty attracting young workers, caused the number of professional glass makers in Murano to decrease from about 6,000 in 1990, to fewer than 1,000 by 2012.
Museum of Glass Murano
Museo del Vetro
Fondamenta Giustinian 8,
Phone +39 041 739586 – Fax +39 041 5275120
Vaporetto: Line 4.1 or Line 4.2, stop – Museo Murano
Opening Hours: from April 1st to October 31st 10 am – 6 pm and from November 1st to March 31st 10 am – 5 pm
Closed on December 25th, January 1st and May 1st Tickets: Full price € 8.00 Reduction € 5.50
————-Venetian Glass – The Story————