The Venetian city state grew during the decline of the Roman Empire as people fled barbarian invasions to the safety of islands in the Venetian Lagoon. Small communities grew in the lagoon, and Venice became the most prominent. The city of Venice became a highly successful trading port, and by the 11th century dominated trade between Europe, North Africa, and the Middle East. It also had a strong navy. 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 glass. Successful trade bred a wealthy merchant class in addition to the nobles, and the wealthy became patrons of Venice's famous art and architecture.
It is thought that glass production in Venice began around 450, as glassmakers from Aquileia fled to the islands to escape barbarian invaders.[Note 1] The earliest archaeological evidence of a glass factory in the area comes from the Venetian lagoon island of Torcello and dates from the 7th to 8th century. The original Venetian glassmakers were joined by glassmakers from Byzantium (a.k.a. Constantinople) and from the Middle East—which enriched their glassmaking 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.[Note 2] Early products included beads, glass for mosaics, jewelry, small mirrors, and window glass.
Venetian glassmaking grew in importance to the city's economy. Around 1271 the local glassmakers' guild made rules to help preserve glassmaking secrets. It was forbidden to divulge trade secrets outside of Venice. If a glassworker left the city without permission, he would be ordered to return.[Note 3] If he failed 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.
Island of Murano
A law dated November 8, 1291 confined most of Venice's glassmaking industry to the "island of Murano". Murano is actually a cluster of islands linked by short bridges, located about 1.2 kilometres (0.75 mi) north of Venice in the Venetian lagoon. The furnaces used to make molten glass were a fire hazard, especially in cities with wooden structures nearby. Moving the glassmaking industry to Murano removed the threat of a disastrous fire in Venice. The move also kept the technology of glassmaking, and the glassmakers, confined to Murano. This prevented the spread of Venetian glassmaking expertise to potential competitors. Glassmakers were not allowed to leave the island without permission from the government. Leaving without permission, or revealing trade secrets, was punishable by death. Locating the industry on a single island also made it easier for the government to monitor imports and exports.
Murano in the 1200s was a summer resort where the aristocrats of Venice built villas with orchards and gardens. It took about an hour to row a boat from Venice to Murano. Although the glassmakers could not leave the island, the nobles had no such constraints. Despite their travel restrictions, the glassmakers lived on a beautiful island, were under the direct rule of Venice's Council of Ten (the Venetian state-security committee), and had extra privileges. They did not work during the hot summer, during which furnace repair and maintenance was performed. During the 1300s, the annual summer vacation lasted five months. In the 1400s, the Venetian government shortened the summer vacation to three and a half months. Murano glassmakers sometimes complained they were not working enough.[Note 4] Glassmakers also enjoyed heightened social status. On December 22, 1376, it was announced that if a glassmaker's daughter married a nobleman, there was no forfeiture of social class, so their children were nobles.