Byzantine craftsmen played an important role in the development of Venetian glass, an art form for which the city is well-known. When Constantinople was sacked by the Fourth Crusade in 1204, some fleeing artisans came to Venice. This happened again when the Ottomans took Constantinople in 1453, supplying Venice with still more glassworkers. By the 16th century, Venetian artisans had gained even greater control over the color and transparency of their glass, and had mastered a variety of decorative techniques.
Despite efforts to keep Venetian glassmaking techniques within Venice, they became known elsewhere, and Venetian-style glassware was produced in other Italian cities and other countries of Europe.
Some of historical factory of glass in Murano are today the most important brand of glass in the world: Venini, Barovier & toso, Pauly, Seguso. The oldest factory of glass are Pauly & C. - Compagnia Venezia Murano (it was founded in 1866)
Murano’s reputation as a center for glassmaking was born when the Venetian Republic, fearing fire and destruction to the city’s mostly wood buildings, ordered the destruction of all the foundries within the city in 1291. Though the Republic ordered the destruction of the foundries it authorized and encouraged construction outside the city, and by the late 13th century the glassmaking industry was centered in Murano. Murano glass is still interwoven with Venetian glass.
Murano's glassmakers were soon the island’s most prominent citizens. By the 14th century, glass makers were allowed to wear swords, enjoyed immunity from prosecution by the Venetian state and found their daughters married into Venice’s most affluent families. Of course there was a catch: Glassmakers weren't allowed to leave the Republic. However, many craftsmen took this risk and set up glass furnaces in surrounding cities and as far afield as England and the Netherlands.
Murano’s glassmakers held a monopoly on quality glassmaking for centuries, developing or refining many technologies including crystalline glass, enameled glass (smalto), glass with threads of gold (aventurine), multicolored glass (millefiori), milk glass (lattimo), and imitation gemstones made of glass. Today, the artisans of Murano are still employing these century-old techniques, crafting everything from contemporary art glass and glass jewelry to murano glass chandeliers and wine stoppers.
Today, Murano is home to the Museo Vetrario or Glass Museum in the Palazzo Giustinian, which holds displays on the history of glassmaking as well as glass samples ranging from Egyptian times through the present day.
The process of making Murano glass is rather complex. Most Murano glass art is made using the lampworking technique. The glass is made from silica which becomes liquid at high temperatures. As the glass passes from a liquid to a solid state, there is an interval when the glass is soft before it hardens completely. This is when the glass-master can shape the material.
The other raw materials, called flux or melting agents, soften at lower temperatures. The more sodium oxide present in the glass, the slower it solidifies. This is important for hand-working because it allows the glassmaker more time to shape the material. The various raw materials that an artisan might add to a glass mixture are sodium (to make the glass surface opaque), nitrate and arsenic (to eliminate bubbles) and coloring or opacifying substances.
Colors, techniques and materials vary depending upon the look a glassmaker is trying to achieve. Aquamarine is created through the use of copper and cobalt compounds whereas ruby red uses a gold solution as a coloring agent. The millefiori technique begins with the layering of sliced canes of glass and conterie or tiny glass beads are formed by cutting thin glass canes into sections when cold then rounded when hot. Filigree, incalmo, enamel painted, engraving, gold engraving, lattimo, ribbed glass and submersion are just a few of the other techniques a glassmaker can employ.
Murano artisans use specialized tools in the making of their glass. Some of these tools include borselle (tongs or pliers used to hand-form the red-hot glass), canna da soffio (blowing pipe), pontello (an iron rod to which the craftsman attaches the glass after blowing in order to add final touches), scagno (the glass-master's work bench) and tagianti (large glass-cutting clippers).