History of glass
Glass remained a luxury material, and the disasters that overtook Late Bronze Age civilizations seem to have brought glass-making to a halt. It picked up again in its former sites, Syria and Cyprus, in the 9th century BC, when the techniques for making colorless glass were discovered. The first glassmaking "manual" dates back to ca. 650 BC. Instructions on how to make glass are contained in cuneiform tablets discovered in the library of the Assyrian king Ashurbanipal. In Egypt glass-making did not revive until it was reintroduced in Ptolemaic Alexandria. Core-formed vessels and beads were still widely produced, but other techniques came to the fore with experimentation and technological advancements. During the Hellenistic period many new techniques of glass production were introduced and glass began to be used to make larger pieces, notably table wares. Techniques developed during this period include 'slumping' viscous (but not fully molten) glass over a mould in order to form a dish and 'millefiori' (meaning 'thousand flowers') technique, where canes of multicolored glass were sliced and the slices arranged together and fused in a mould to create a mosaic-like effect. It was also during this period that colorless or decolored glass began to be prized and methods for achieving this effect were investigated more fully.
History of glass
This account is more a reflection of Roman experience of glass production, however, as white silica sand from this area was used in the production of glass within the Roman Empire due to its high purity levels. During the 1st century BC glass blowing was discovered on the Syro-Judean coast, revolutionizing the industry. Glass vessels were now inexpensive compared to pottery vessels. A growth of the use of glass products occurred throughout the Roman world. Glass became the Roman plastic, and glass containers produced in Alexandria spread throughout the Roman Empire. With the discovery of clear glass (through the introduction of manganese dioxide), by glass blowers in Alexandria circa 100 AD, the Romans began to use glass for architectural purposes. Cast glass windows, albeit with poor optical qualities, began to appear in the most important buildings in Rome and the most luxurious villas of Herculaneum and Pompeii. Over the next 1,000 years, glass making and working continued and spread through southern Europe and beyond.