To begin only the finest raw material is used:
-Sand: silica 70%
-Soda: sodium carbonate
-Chile saltpeter: sodium nitrate
The Fusion Process:
The raw materials are mixed together in the heat-resistant crucible (ceramic or metal container) and then fused in a kiln that can reach up to 1.400°C.
The Murano glass in its basic composition is colorless. The colors are obtained by adding small amounts of minerals, oxides, and chemical derivatives to the base composition of the glass powder.
The kilns, “fornaci”, used nowadays on Murano are large with a maximum capacity 2000 pounds. There are also kilns made up of a number of smaller containers with capacity varying from 10kg to 2 hundred pounds, the smaller crucibles being used for colored and opalescent glass.
Modern-day kilns on Murano are equipped with heat retainers and with equipment that makes it possible to control temperature and the rate of fuel combustion.
Raw materials used for creating Murano glass are fused in a kiln at a temperature of 2500 degrees fahrenheit.
When the elements are fused together, the temperature of the viscous paste is lowered from 2500 degrees F to 2,000 degrees F.
At this point, the paste is removed from the oven as it is “solid” enough to be shaped by the glass artisan. When the artisan is done with his creation, he lets the glass set at a temperature between1,000 and 1,200 degrees F . The glass must be cooled slowly.
In fact, since glass is a poor conductor of heat, the inner and outer surfaces tend to cool at different rates. If the process happens too quickly, tensions within the glass can lead it to crack. Even some time after it has cooled completely. This slow cooling process takes place in what are known as “annealing ovens”, where the temperature is slowly decreased.
The raw materials used to tune the proprieties of Murano Glass are called flux or melting agents, which soften at lower temperatures.
Sodium oxide, for example, slows down the solidification process. Therefore, it is often used in Murano for doing freehand glasswork or “a mano volante”. This way the glassmaker has more time to shape the material.
Other raw materials often added to glass mixtures are sodium, nitrate, and arsenic. Sodium, for example, is used to make the glass surface opaque. Nitrate and arsenic, on the other hand, help to eliminate bubbles within the glass. Other substances are added to glass mixtures to either color or opacify the final product.
To make complex Murano Glass pieces the Master sets up and coordinates his team. The team, or “piazza”, consists of 2 or 3 people which help him in making of the piece.
The “serventino” handles the blowpipe. To do so, he takes molten glass from the kiln and rolls it against an iron plate, or “bronzin”.
The “servente” blows in the pipe creating a balloon, or “colletto”. He then rolls it again against the iron plate, to ensure symmetry. At this point, artistic work must immediately begin.
The Master quickly works with his tools on the viscous Murano glass mass whose temperature is rapidly dropping.
The Master must work very quickly for two reasons. Firstly, because if the temperature drops below 1,000 degrees F, the glass becomes totally rigid and fragile. Secondly, because a sudden decrease of the temperature creates tensions in the glass and lead it to eventually break.
During the process, the Master often interrupts his work to let his team heat up the glass again. The temperature must increase but not too much, or the piece could lose its shape. The heated piece is then handed back to the master who continues modeling it. If more material is required for the work, further glass is heated and added.
When the piece is done, it is put in a kiln (“muffola”) at a lower temperature than the main oven. The temperature is then slowly lowered (“tempera”) until it reaches the room temperature.
So How can you identify an original Murano Glass object?
2) When Murano artisans make glassware, they use various minerals to give color to the glass mass. As the glass mass gets heated, the minerals melt and give transparent glass specific colors, such as blue from cobalt or red from gold, green from iron, or pink from manganese. Often the colors get layered on top of each other in a special technique called Sommerso. In addition, the masters often use thin sheets of gold or silver that get added to the glass mass and create a layer of gold or silver sparkles inside the glass. A special demonstration of mastery, the artisan may create glassware that looks like a bright quilt of mosaic-like pieces, the ancient Roman technique known as Millefiori or Murrina.
My Italian Decor hand blown pieces include fruit sculpted in to pears, apples, lemons or limes, as well as stylized mosaic glass pieces. Each has a distinct shape and vibrant coloring and includes the technique called Sommerso.
3) Authentic Murano Glass contains small imperfections in size, shape and content:
When masters create Murano Glass by hand, they do not use exact measurements or machines to create perfect shapes or perfect polish. Therefore, most Murano Glass pieces may come out slightly asymmetrical, with bottoms that have slightly rough pontil marks where the glass piece was taken off the stick. There may be bubbles captured inside the glass. Two items of the same model may vary in terms of shape, size, color, shade, or pattern. The process is manual and ancient, where only the same basic tools are used. Masters take pride following these techniques and traditions of their fathers and grandfathers. My Itlalian Decor is dedicated to offering this traditional art form to all its customers.
4) Murano glass color is unique:
Colored glass is achieved by adding selected chemical compounds to the silica during melting. Incredible amount of accuracy is required in terms of proportions, heat and timing. Aquamarine color is formed when cupric oxide is added to the blend. The color red is created when cuprous oxide is added to the blend, blue when cobalt oxide is added to the blend and green when iron oxide and chrome oxide are added to the blend.
Red, the most difficult of colors to master is a signature of authentic Murano glass. Many of the particular shades are still secrets held by some glassmaking factories and not shared, even within Murano.
5). Authentic Murano Glass is sold in physical stores or on websites, like My Italian Decor
If a store, whether physical or online, sells large gorgeous colorful vases, sculptures, and recognizable expensive typically Venetian pieces such as gondolas, lovers, Moores, clowns, Goldonian ladies and gentlemen, Millefiori glassware, as well as elaborate Venetian chandeliers, most likely this store carries genuine Murano Glass from a number of highly skilled masters and factories.
6) Authentic Murano Glass sellers know Murano Glass and are able to answer all your questions
If you are unsure and can’t decide on the purchase, have a conversation with the seller and business owner of My Italian Decor, Elizabeth Graceffo. Ask her about the piece, its technique, and the glass-making process, and question her about Murano and Venice. Her level of knowledge and expertise is a testament to her authority on real Murano Glass. While her relationships with artists and their locations are proprietorial information, rest assured the piece that captures your attention, is the real deal.