Core-formed and cast glass vessels were first produced in Egypt and Mesopotamia as early as the fifteenth century B.C., but only began to be imported and, to a lesser extent, made on the Italian peninsula in the mid-first millennium B.C. By the time of the Roman Republic (509–27 B.C.), such vessels, used as tableware or as containers for expensive oils, perfumes, and medicines, were common in Etruria (modern Tuscany) and Magna Graecia (areas of southern Italy including modern Campania, Apulia, Calabria, and Sicily). However, there is very little evidence for similar glass objects in central Italian and Roman contexts until the mid-first century B.C. The reasons for this are unclear, but it suggests that the Roman glass industry sprang from almost nothing and developed to full maturity over a couple of generations during the first half of the first century A.D.
Doubtless Rome’s emergence as the dominant political, military, and economic power in the Mediterranean world was a major factor in attracting skilled craftsmen to set up workshops in the city, but equally important was the fact that the establishment of the Roman industry roughly coincided with the invention of glassblowing. This invention revolutionized ancient glass production, putting it on a par with the other major industries, such as that of pottery and metalwares (as 20.49.2-12). Likewise, glassblowing allowed craftsmen to make a much greater variety of shapes than before. Combined with the inherent attractiveness of glass—it is nonporous, translucent (if not transparent), and odorless—this adaptability encouraged people to change their tastes and habits, so that, for example, glass drinking cups rapidly supplanted pottery equivalents. In fact, the production of certain types of native Italian clay cups, bowls, and beakers declined through the Augustan period, and by the mid-first century A.D. had ceased altogether.
However, although blown glass came to dominate Roman glass production, it did not altogether supplant cast glass. Especially in the first half of the first century A.D., much Roman glass was made by casting, and the forms and decoration of early Roman cast vessels demonstrate a strong Hellenistic influence. The Roman glass industry owed a great deal to eastern Mediterranean glassmakers, who first developed the skills and techniques that made glass so popular that it can be found on every archaeological site, not only throughout the Roman empire but also in lands far beyond its frontiers.
Although the core-formed industry dominated glass manufacture in the Greek world, casting techniques also played an important role in the development of glass in the ninth to fourth centuries B.C. Cast glass was produced in two basic ways—through the lost-wax method and with various open and plunger molds. The most common method used by Roman glassmakers for most of the open-form cups and bowls in the first century B.C. was the Hellenistic technique of sagging glass (81.10.243) over a convex “former” mold. However, various casting and cutting methods were continuously utilized as style and popular preference demanded. The Romans also adopted and adapted various color and design schemes from the Hellenistic glass traditions, applying such designs as network glass and gold-band glass to novel shapes and forms. Distinctly Roman innovations in fabric styles and colors include marbled mosaic glass, short-strip mosaic glass, and the crisp, lathe-cut profiles of a new breed of fine as monochrome and colorless tablewares of the early empire, introduced around 20 A.D. This class of glassware became one of the most prized styles because it closely resembled luxury items such as the highly valued rock crystal objects, Augustan Arretine ceramics (as 10.210.37), and bronze and silver tablewares (as 20.49.2-12) so favored by the aristocratic and prosperous classes of Roman society. In fact, these fine wares were the only glass objects continually formed via casting, even up to the as Late Flavian, Trajanic, and Hadrianic periods (96–138 A.D.), after glassblowing superceded casting as the dominant method of glassware manufacture in the early first century A.D.
Glassblowing developed in the Syro-Palestinian region in the early first century B.C. and is thought to have come to Rome with craftsmen and slaves after the area’s annexation to the Roman world in 64 B.C. The new technology revolutionized the Italian glass industry, stimulating an enormous increase in the range of shapes and designs that glassworkers could produce. A glassworker’s creativity was no longer bound by the technical restrictions of the laborious casting process, as blowing allowed for previously unparalleled versatility and speed of manufacture. These advantages spurred a rapid evolution of style and form, and experimentation with the new technique led craftsmen to create novel and unique shapes; examples exist of flasks and bottles shaped like foot sandals, wine barrels, fruits, and even helmets and animals (17.194.251; 17.194.231). Some combined blowing with glass-casting and pottery-molding technologies to create the so-called mold-blowing process. Further innovations and stylistic changes saw the continued use of casting and free-blowing to create a variety of open and closed forms that could then be engraved or facet-cut in any number of patterns and designs.
At the height of its popularity and usefulness in Rome, glass was present in nearly every aspect of daily life—from a lady’s morning toilette to a merchant’s afternoon business dealings to the evening cena, or dinner. Glass alabastra (17.194.286), unguentaria, and other small bottles (30.115.16; 17.194.259) and boxes held the various oils, perfumes, and cosmetics used by nearly every member of Roman society. Pyxides (91.1.1335) often contained jewelry (74.51.4244, 17.194.332, .334, .344, .346) with glass elements such as beads, cameos, and intaglios (41.160.710), made to imitate semi-precious stone like carnelian, emerald, rock crystal, sapphire, garnet, sardonyx, and amethyst. Merchants and traders routinely packed, shipped, and sold all manner of foodstuffs and other goods across the Mediterranean in glass bottles and jars of all shapes and sizes, supplying Rome with a great variety of exotic materials from far-off parts of the empire. Other applications of glass included multicolored tesserae used in elaborate floor and wall mosaics, and mirrors containing colorless glass with wax, plaster, or metal backing that provided a reflective surface. Glass windowpanes were first made in the early imperial period, and used most prominently in the public baths to prevent drafts. Because window glass in Rome was intended to provide insulation and security, rather than illumination or as a way of viewing the world outside, little, if any, attention was paid to making it perfectly transparent or of even thickness. Window glass could be either cast or blown. Cast panes were poured and rolled over flat, usually wooden molds laden with a layer of sand, and then ground or polished on one side. Blown panes were created by cutting and flattening a long cylinder of blown glass.