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.
Byzantine glass
In the middle Byzantine period, Byzantine glass-makers adopted silver-staining techniques from the Arab world. Silver-stained glass is created by applying a metallic compound, mixed with a "carrier" of clay or ochre to the surface of the glass object, then the glass is fired below the softening point of the glass. This process results in the breakdown of the smeared compound and its transition into the body of the glass object, creating a "stained" effect. Depending on the makeup of the compound and the "carrier" this process can lead to a wide array of colors. While the Arabs began creating silver-stained glass objects in the late eighth century in Egypt, the first Byzantine silver-stained object has been dated to the ninth century. The most common items featuring Byzantine silver-stain are simple glass bracelets, dating from the tenth to thirteenth centuries, and being discovered across the Byzantine world, from Greece to Anatolia. The most famous example of Byzantine silver-staining is the interior inscription of the beautiful San Marco bowl, dated to the "Macedonian Renaissance" of the tenth century. Several fragments of silver-stained window glass have been discovered. Although silver staining was practiced by the Byzantines, silver-stained works were not as ubiquitous in Byzantium as they were to become in late Medieval Europe. However, the widespread use of silver-staining in Byzantium could in part explain the transmission of silver-stain technique from the Arab world to Western Europe.