Glassmaking technique: mosaic glass

(lute playing softly) - [Voiceover] Mosaic glass vessels are made from long canes of glass that are cut into thin sections and then fused together. To make a spiral cane, a mass of colored glass is thinly coated in colorless glass, then rolled on a marver to give it a cylindrical shape. The glass is flattened by pressing it against the marver with another tool. Gradually, the flattened glass is pulled to form a thick ribbon. The ribbon is rolled up onto itself. The glass is then cut free of the metal rod. The rod is reattached, but this time to the side of the rolled up glass. After reheating, a second rod is attached to the other side. The rolled up ribbon is gently stretched from its edges to form a long cane. The cane is cut into manageable lengths. Once cooled, the cane is cut again, this time into thin sections. The sections are arranged on a ceramic slab, and then placed into a furnace. After the glass softens, and begins to flow slightly, any gaps are squeezed closed. While the mosaic sections are still soft, a decorative edge cane is added. After further reheating, the sections and edge cane are squeezed and pressed together, to form a perfectly flat disk. The disk is transferred to a slumping form, and placed into the furnace. After a few seconds, gravity forces the glass downward over the form. As the glass and form cool, they can be separated. Finally, after annealing, or slow cooling, the bowl can be ground and polished. (lute playing softly)