Excavations carried out at Khirbet (ruins in Arabic) Castra, the site of the ancient Byzantine city of Castra, revealed a large trove of exquisite Roman and Byzantine glassware.
The site known as Khirbet Castra lies to the south of Haifa in Israel, at the base of the western flank of Mount Carmel, some one and half kilometers from the coast. The ancient city of Castra was one of the most important places in the reign of the Byzantine era; it combined the advantages of its location on the coast with flourishing economy of the Carmel range.
The name Castra is to be found in Jewish sources of the fourth century AD, where it is described as a hostile and alien city adjacent to the Jewish city of Caifa or Caiphas (Haifa). "The Lord said unto Jacob your enemies surround you, as does Halamish to Neve, CASTRA TO HAIFA'...." (Talmudic commentary to the Song of Songs). In Christian sources of the sixth century AD, the title Castra of the Samatarians' appears in the text of his travels by the pilgrim Antonius Placentinus (Piacenza), who describes the route from Acre to Haifa, "Castra of the Summerians lies one mile from Sycamina, at the foot of Mount Carmel.."
To date, no traces have been found of a Roman settlement, though the rich findings from some of the tombs are very definitely of Roman provenance. From the fourth century till the beginning of the seventh century, in the Byzantine era, the site was continuously inhabited, and the city grew and flourished. (During the latter Arab conquest, the city dwindled in importance and ruin followed. During the Ottoman era, an Arab settlement (Kfar Samir) was built on the ancient ruins.)
To the west of the city lie the burial grounds with individual tombs, burial niches, burial chambers, and pottery sarcophagi. Most of these are from the Late Roman and Byzantine era. A wealth of burial offerings have been found in the tombs - gold jewelry, artifacts of bone, stone and ceramics, varied Roman and Byzantine coins and complete glass vessels...
Hundreds of undamaged glass vessels have been found in the graves of Castra, as part of the burial offerings. They were found in tombs uncovered during archaeological excavations; the vessels found, were created by varying techniques, some by blowing in a mold, some with engraved horizontal lines on the body, and some by the addition of handles of various type. (It is possible that a local glass industry existed in the city or its environments.) Roman and Byzantine shapes and ornamentation on the glassware were extremely varied which display the great technical ability and artistry.
Glass manufacture became important in all the areas under Roman hegemony. In fact, the first four centuries of the Christian era may justly be called the "First Golden Age of Glass". The craftsmen of that early period were masters of their trade. They were well versed in the making of relatively clear transparent glass. These craftsmen knew of glass blowing, stained glass, and gilding. They knew of the techniques of building up layers of glass of
different colors, and cutting out designs in high relief.
Glass blowing techniques:
The most innovative type of glass crafting, during the Roman era, and even in the history of glass manufacture, was glass blowing. It could of been a stroke of inventive trial and error that glass on the end of hollow metal tube can be blown in a mold; shaped freehand into a form required, and handles, feet and decoration / ornamentation can be added at will. This liberating discovery, around the first century AD, gave rise to the growth of glass manufacture during the Roman era. The skill of the ancient craftsmen astonishes and even baffles the modern technician; common containers in various shapes and sizes produced in common greenish glass were on a scale unmatched till the nineteenth century.
The credit for the discovery of glass-blowing can be credited to Syrian glassworkers who had migrated to Rome where the demand of the their skilled products found a ready market: Evidence to this can be found in the first mold glass artifacts bearing the signature of Syrian master craftsmen and that the ductile soda ash of the Syrian provinces was aptly suitable for the new invention of glass-blowing. Thus, in the course of time, Italy (and its provinces), from the early first century AD, became important glass-producing areas. Glass engraving flourished there and particularly by one form of glass art - "Cameo Glass" - grinding through an opaque white layer to a darker ground in which a design has been treated in the manner of a cameo.
Glass-making spread from Italy to other parts of the Roman Empire - from Gaul to the valleys of Rhone and Rhine. The Rhineland, within time, became another great center of glass making of the Roman world. Several types of glass ornamentation were the specialties of the district - i.e. glass artifacts decorated in serpentine patterns by threads trailed on and then pressed flat and notched are typical and important (Schlangenfadenglaser).
When the Byzantine Empire with its capital Constantinople was founded in the 4th century AD, glass manufacturing was at its height - the manufacture of stained or colored glass was well developed. (Emperor Justinian in the sixth century employed skilled glass artisans to install magnificent gold-ground mosaics in his great church, Hagia Sophia.) The evidence of the importance of Byzantine glass decoration can be bourn out with the edicts of emperors Constantine the Great, Theodosius, and Justinian, which gave distinction between glass-makers (vitrarii), and the skilled glass cutters (diatretarrii). Thus, by these edicts it suggests those glass (cutters) engravers played an important role in Byzantine glass making.
With the breakdown of the Empire, glass-making fared differently in various parts of the former Roman world. In the East, life continued relatively undisturbed and glass-making evolved to patterns of Islamic shape and design. But, in the northern provinces, glass-making turned into a cottage industry producing relatively simple shapes, coloring and ornamentation. (From 500 AD, however, innovative designs were again displayed in the crafting of elaborate and fantastic creations. i.e. "claw beakers" (Russelbecher) - rows of trunk like protrusions running down the side of the vessel to small button feet.)
One can then assume that some of the glass vessels found in the tombs of Castra must be attributed to the late Roman period, although they were found in mixed burial areas together with Byzantine glass artifacts. Some of these pieces, mainly of Roman origin, found in the burial sites were heirlooms and those with characteristics of the Local artisans crafted eastern provinces.
Alexandrian Glass Artisans:
Throughout the Roman era there were two main groups of skilled glass artisans - the Alexandrian (and the Syrian). Although the Romans were not glass-making people they fully appreciated the beauty and texture of artifacts crafted in glass. Transparency and sheerness were the dominant characteristics.
During the Ptolemaic era, around the first century BC, Alexandria became an important glass-making center under Pax Romana. Mold pressing was an Alexandrian technical process, which produced vessels with diversity of designs and of infinite variety - with a combination of designs of millefiori' ("thousand flowers") patterns. Other glass vessels were compounded with mica chips of hematite to give the appearance of aventurine' glass (glittery opaque glass). Sometimes glass was irregularly compounded to give the effect of veined stone; or with occasionally enclosures of gold leaf to simulate the glitter of natural pyrites.
Pieces were then threaded with white opaque thin glass canes to make a vessel of lacy appearance. Some of the glass pieces were finished with a fire polish by returning them to the oven - but many mold pieces were, in fact, given a rotary polish by lathe-work or with abrasives.
It was the Alexandrians who originated glass cutting. From simple engraving in the beginning to more elaborate forms done with cutting and polishing wheels - finally relief engraving made its appearance. The skill of the Alexandrian glass engravers has never been excelled and seldom equaled.