Technology of Roman glassworks in the Rhineland

The report deals with the excavation of glass plants of the late antiquity in the Hambach forest area, North Rhine-Westphalia (Germany). Within the la st 20 years, five Roman glass plants have been excavated there at an open-c ast lignite mine near the town Julich. Four glass plants were discovered mo re or less by accident in the course of excavations of Roman "villae rustic ae". The fifth and last one (place HA 132) was the subject of a carefully p lanned project in order to learn more about Roman glass manufacture. The ex cavation started in 1994 and ended in summer 1996. It was the first complet e large-area excavation of an ancient glass factory in Germany. What remain ed of the structure was directly beneath the surface and only low stone fou ndations revealed the shape of the furnaces. There were two types, one circ ular the other semicircular. A comparison with the earlier excavated furnac es in the Hambach area revealed the same shape and structural elements and therefore identical functioning. Also, the refractories, pot fragments and glass remains of all five plants proved to be identical in color, shape, an d quality. Numerous finds of uniform raw glass (frit) proved that the Hambach glasswor ks were processing plants where natural-colored household vessels were made from delivered raw glass. After determination of the type of glass plant, it was possible to understand the functioning of the glass furnaces. Glass processing plants need two types of furnaces: the melting (pot) furnace and the annealing oven (lehr), both working in local and temporal connection. By understanding function one can reconstruct an object. There are archaeol ogical and documentary clues that raw glass was an important commodity. The re were factories producing raw glass and others processing it. Produced in Egypt or the Levante, frits were shipped to all other parts of the ancient world.