Venetian glass may be traced back until the 13th Century. From early on colors have always been one of the main features of it. Thanks to the use of the blow pipe, the local production there has evolved in such a way to become a world leading center, not only for the great variety of colors but also for the techniques.
The blowpipe was already used in the 1st Century B.C by the Phoenicians along the Syro-Palestinian coast, travelling through the Roman Empire to Europe. The first glassblowing workshops were established in Rome, the heart of the Empire and then later in other provinces of Italy, like Campania, Morgantina and Aquileia.
In the 13th Century, after the Fourth Crusade in 1204, they were also established in Venice by some of the fleeing artisans from Constantinople and then further reinforced in the 15th Century, after the Ottomans took Constantinople in 1453, with the arrival of more glassworkers.
Around the same year Angelo Barovier, belonging to the Barovier & Toso dynasty among the oldest glass masters since 1295, invented “cristallo” glass, a totally clear glass, without the slight yellow or greenish color originating from iron oxide impurities, thanks to small additions of manganese oxide.
On one hand Venetian glass has gained its position in the world thanks to the many colors and techniques, on the other the crystal clear glass invention of the Barovier family allowed it to become a valid alternative to crystal.
Crystal has always been considered more precious than glass because of its higher index of refraction. The beauty of crystal is its sparkle, thanks to the specular reflection and the range of angles of total internal reflection which are increased. When crystal contains up to 35% lead then it has the most sparkle.
Countries which are specialized in lead crystal production, among which drinking glasses, decanters, chandeliers are France, England, The Netherlands, Hungary, The United States, Ireland, Canada, Taiwan, Austria and the Czech Republic.
Many do not know that Bohemian crystal, which is world famous, is a non-lead crystal. It contains potash and chalk, which combination creates a clear colorless glass. Furthermore it is quite rich in limestone and silica.
Venetian glass or Murano glass is a blend of silica, melting agents called flux, sodium oxide (to slow down the solidification process allowing more time to shape the item), sodium (to make the glass surface opaque), nitrate, arsenic (to eliminate bubbles) and coloring or other substances (to obtain mat glass).
The coloring agents are mainly metallic oxides which determine the glass color. The beauty of Venetian glass is to be found in its unlimited colors, such as for example:
-aquamarine when cupric oxide is added to the blend,
-red when cuprous oxide is added to the blend,
-blue when cobalt oxide is added to the blend,
-green when iron oxide and chrome oxide are added to the blend,
-violet when manganese dioxide is added to the blend (depending on the quantity),
-black when manganese dioxide is added to the blend (depending on the quantity),
-brown when iron is added to the blend (depending on the quantity),
-antimony yellow when iron is added to the blend (depending on the quantity),
-ruby when a small percentage of gold or limited amount of copper is added.
There are many other colors and each furnace has secret recipes that are jealously kept in order to come up with something new and special. To make opaque glass the blends are basically the same as the transparent ones, however with the addition of white opal glass as a base.
If you have a chance to go to Murano, take your time to visit the Glass Museum in order to admire the hundreds of beautiful colored Venetian glass items from early ages until now.