Blue ribbed bowl
Period: 1st century A.D.
Material: Cobalt blue glass
Dimensions: Height: 4.5 cm, diameter: 16 cm
Ex-Japanese private collection, assembled in the 1980s-1990s
Complete and in good condition, but reglued from several fragments. Superficial wear and minor chips.
This shallow, thick-walled bowl is outstanding both for its excellent state of preservation and for its perfect shape. It was worked in a beautiful cobalt blue glass; the horizontal lines were incised by grinding as the piece was rotated on a lathe. The tall, smooth rim is barely rounded; the inner decoration is embellished by two incised lines near the bottom and by a small central circle. The slightly concave base provides the vessel with good balance.
The bowl is simply adorned with a horizontal frieze of vertical ribs, engraved on the lower body; their presence recalls the metallic origin of the vessel, inspired by the gadroon vases made of precious metal.
The obvious differences between each rib prove that they were not molded, but rather handmade after the body was modeled. According to modern experiments, it appears that the craftsman could produce these vessels very quickly by simply placing a very hot glass disk on a semispherical mold, which was then spun on a potter’s wheel. Given its flexibility, the hot glass adapted perfectly to the mold profile. The rim and the ribs were then shaped immediately (during the rotation of the lathe) using a short stick on the edge and another longer, narrower stick on the body.
This process allowed the bowl to be manufactured rapidly (in about a minute, according to some modern tests); indeed, in order to meet the incredible success of this form, the craftsman had to work as fast as possible, while ensuring excellent quality.
Ribbed cups and bowls can differ greatly in their type and color. The first examples of ribbed bowls date back to the second quarter of the 1st century B.C.; from the middle of that century, the shape suffered a minor variation, with the adoption of a flatter or slightly concave bottom, which made the vessel more stable. Their production increased considerably from the late Hellenistic period on and continued during the 1st century of the Empire with a very elaborate typology and various dimensions. The most common colors were fi rst orange-brown, cobalt blue and aubergine; these were gradually replaced by light blue, dark and light green around the mid-1st century A.D., when the taste for bright colors became old-fashioned.
These bowls were largely used as tableware across the Mediterranean world, from Italy to the more western and northern colonies of the Empire, from the Aegean to Anatolia and the Levant.
On the production of these vessels and on some related examples, see:
ARVEILLER-DULONG V. and NENNA M.-D., Les verres antiques du Musée du Louvre : Vol. I, Contenants à parfum en verre moulé sur noyau et vaisselle moulée, VIIe siècle av. J.-C.-Ier siècle apr. J.-C., Paris, 2000, pp. 187-193.
GROSE D.F., The Toledo Museum of Art: Early Ancient Glass, New York, 1989, pp. 72-79 (technique) and 307 ff.
LIERKE R., Antike Glastöpferei: Ein vergessenes Kapitel der Glasgeschichte, Mainz/Rhine, 1999, pp. 51 ff. (technique).
MATHESON S.B., Ancient Glass in the Yale University Art Gallery, New Haven, 1980, pp. 14-16.