Pay More

from Frederick Carder: Portrait of a Glassmaker by Paul V. Gardner

p. 27

Many other uses of powdered glass were successful in the late teens and twenties. Among them was Cluthra, often described as Cintra with bubbles. Unwanted bubbles have been the bane of glassmakers for centuries. While Carder made fine transparent glass free from bubbles, he also appreciated the use of bubbles to enhance this medium. He often said, “bubbles give life to the glass” and that he “got so sick of people complaining about an occasional tiny bubble which got by inspection” that he decided to put in a lot of bubbles and “make ’em pay more” for the bubbly piece s. The bubbles in Cluthra were due to what he called “a chemical” (probably potassium chloride) mixed with the powdered glass on the marver. This “chemical” produced bubbles in the powdered glass when exposed to the heat of the parison. A layer of crystal glass gathered over the parison, encrusted with the bubbly powdered glass at just the right moment, locked the powdered glass and bubbles forever in delightful suspension.