Listen as former curator David Whitehouse describes a ribbon glass cup. A new variety of mosaic glass was introduced in the first century B.C. It was “ribbon” mosaic, and the ornament consisted mainly of lengths (not slices) of canes arranged in geometric patterns.
This concave-sided cup is a typical example. Many slices of just a few canes with different patterns were laid side by side on a flat surface and fused to form a disk. The disk was then placed on a convex mold and heated until the glass softened and slumped over the mold.
The glassmaker then applied a softened spirally twisted cane to make the rim, and he finished the object by grinding and polishing. The fashion for brightly colored glass lasted until the mid-first century A.D., when colorless glass gained popularity.