Tortoise Shell Spiral Flute. The Tortoise Shell Series is a magical marriage of classical forms and boldly elegant color. The result is a contemporary work of functional art. Based on a proprietary process developed by Michael Cohn in the early 1970’s, the Tortoise Shell pattern has evolved over many years into one of the Studio’s signature lines. The process is complex, special furnaces were constructed to melt the four glasses required. In making a Tortoise Shell piece, the first step is to gather a molten 2100 degree opaline luster glass onto the blowpipe and form it into an elongated bubble. This becomes the inside of the piece and provides the luminescent golden glow which sparks the warmth of the Tortoise Shell pattern. Next, a milk glass layer is added, over which a special chemical mixture is applied. A very spectacular chemical reaction occurs when a layer of small chips of a third formula of colored glass is added. Precise temperature and atmosphere in the glory hole (reheating furnace) are critical to obtaining the desired color and character of the design. Finally, the decorated bubble is encased with crystal clear glass and blown into its final form. Each piece is created with a unique richness and depth of patterning a timeless combination of contemporary and classical art.