The invention of glassblowing in the first century B.C. in the Syro-Palestinian region created a remarkable change in the use and availability of glass objects. Previously, from the third millennium B.C., glass objects had been made using other techniques, such as casting in a mold or forming glass around a removable core. These methods were slow and labor-intensive; consequently, glass was made in relatively small quantities and was not widely available. Glassblowing—in which molten glass is gathered on the end of a blowpipe and a vessel is formed by inflation and manipulation with tools—enabled craftsmen to create vessels quickly and in a wide range of shapes, making glassware affordable and available (The Corning Museum of Glass: 54.1.73, 54.1.129, 50.1.38).
The surface of most utilitarian objects was not decorated; as glass objects were principally designed for everyday use, the majority of ancient glass preserved today, in complete or fragmentary form, is plain. This type of glass is often regarded as “study” material by collectors, who favor more artistically accomplished objects. Undecorated objects, however, represent a continuity of traditions through their shapes and forms or because their practical functions deserve closer examination. When a plain glass vessel is placed in the proper context and systematically analyzed, its shape, color, and technical details can be as revealing as those of any elaborately decorated object and may provide links otherwise difficult to understand.
Carboni, Stefano and Qamar Adamjee. “Blown Glass from Islamic Lands.” In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/blow/hd_blow.htm (October 2002)