Glass Coloring Technologies of Late Roman Cage Cups : Two Examples from Bulgaria
Résumé
This article presents the results of recent analytical work (LA-ICP-MS) performed on fragments from two cage cups: a figural beaker found near the ancient town of Serdica, modern Sofia, and a beaker with an inscription found near Yambol. In a set of 12 fragments, the authors identify two different chemical compositions of colorless glass, three compositions of blue glass, and one composition each for green-blue and purple glass.
The new data allow these scholars to investigate the relationship between the colorless main body and the colored external layers of the cage cup blanks, and provides hitherto unsuspected insights into the making of blanks. Two of the blue compositions are unrelated to the colorless base glass, but the other three colored compositions were probably produced by the addition of coloring materials to the colorless glasses of the blanks.
This technological approach seems to be beneficial for securing adequate annealing and compatibility when different glasses are combined in a single blank and intended for further elaborate cold working.