Murano Glassmaking Techniques
Glass is a solid matter which, in its raw state, is made of siliceous sand, soda, lime and potassium melted together in an oven at a temperature of 1500 degrees Celsius (~2,700 Fahrenheit), to become a flexible material. Then, in the simplest scenario, the glassmaker removes this substance from the oven with the help of a pipe, and shapes it using various specialized instruments that changed little since antiquity, such as pliers, scissors and wooden shovels. "Glass-blowing" refers to a method of blowing inside the pipe to give the glass object a form.
The magnificent appearance and coloring of Murano glass is achieved by adding gold or silver foil to the glass mixture and/or adding minerals such as zinc for white, cobalt for blue, manganese for violet, and so on. Once the object is finished, it is placed in a cooling oven, called "tempera", to cool down slowly; in this way it doesn't break due to the extreme variations in temperature.
|Clear glass that features metal particles embedded into it to create a shimmery, sparkling look. The particles are made out of copper or other metal oxides. This manufacturing process is very difficult, and has been invented in the seventeenth century. It is said that avventurina glass was invented by accident when a Murano glass maker spilled copper filings into the glass he was working. The glass that resulted from that lucky occurrence was named avventurina - from Italian word "ventura" (translated as "fortune" or "chance").|
|Glass which is decorated with a regular pattern of evenly spaced air bubbles that become gradually larger or smaller. This widely used art glass technique was especially popular with Murano glass artists during the 1950s.|
|Glass featuring polychromatic veins running through the dark-colored glass. This look is obtained by mixing various metal compounds in a certain fashion, to imitate the natural stones such as chalcedony, agate, and malachite. It was known and used in ancient Egypt, and then re-discovered in Murano in the fifteenth century. The secret of the technique was then lost again and subsequently re-discovered by Lorenzo Radi in the later part of the 19th century.|
|Extraordinarily difficult technique which consists of first fusing two glass layers of different colors, and then raised-carving the object to create a design based on revealing portions of the underlying colors . The first known examples of the use of this technique date back to first century A.D. The technique was particularly popular in early 20th century in Britain.|
One of the best known examples of this technique is The Great Tazza - an elaborate ornate bowl that is based on five layers of different colored glass. The piece was presented to much amazement at the 1990 Paris International Exhibit.
|Venetian crystal is the first truly colorless glass, invented in 1450 by Venetian glass master Angelo Borovier, and obtained by bleaching glass mixture using manganese or other decolorants. It is a fragile sodium-based glass, and is best suitable for manual etching.|
|'Fenicio' (Phoenician) is a technique used to produce festooned motif on glass. It was adopted in Murano at the end of the 17th century, though it was used on glass as far back as the 2nd millennium AD. To achieve this decoration, the glassworker wraps the incandescent glass threads with a thin pontil, or "speo", and then while the object is still hot, he combs the threads with a hooked tool, called a "maneretta". Then, once the threads are merged into a single piece of glass, the obtained decoration is similar to festoons or feathers.|
|Filigrana is a name used to describe several techniques to create glass formed by colorless or white rods with inner threads of white, golden or colored glass. The technique is called "reticello" when the threads cross and form a grid, where small air bubbles form in between the threads. Glass is called "a retorti" or "retortoli" when threads form a spiral pattern and do not cross. This is one of the most ancient techniques, that has been in use as early as the sixteenth century.|
|The term comes from the Italian for "ice". This kind of glass appears cracked on its entire surface. This effect is obtained by immersing still hot shaped glass object in cold water and then covering the crackles with another layer of glass. It was very popular from the 16th to the 18th centuries. This results in a finely-crackled glass surface similar to crocked ice.|
|An ancient glass technique requiring a particular dexterity from the master performing it. It is used to create objects formed by separate parts blown one at a time, usually of different colors, and then joint together while still warm, and shaped to the desired form.|
|(From Italian "latte" - milk). Opaque white glass produced for the first time in Murano in the fifteenth century, imitating the look of fine china. It was originally used for manufacturing objects decorated with multicolored enamels.|
|(From Millefiori - "a thousand flowers"). The basis of this technique is the use of glass canes (rods) which contain a single flower design visible only on the surface of cross sections of the cane. The object is then formed using the cross-sections of multiple such rods, which are melted together to cover the surface of the glass object. This technique was first used in Egypt between the third and the first century B.C.|
|(From Italian "Sommerso" - submerged). Creates a layered appearance where one colored layer of glass is covered by another layer of differently-colored glass. This effect is achieved by repeatedly dipping a glass object into molten glass of another color. This technique was invented in Murano in 1930's.|