Jobs - Glass Blower

From Charleston Footprints:

I am often asked why the old panes of glass on Charleston’s historic buildings have a ripple or wavy texture. The answer comes from the old methods of making window panes. Prior to the 1830’s, glass was made by hand, as individual artisans created windows with a simple, rustic process. The basic ingredients of soda and lime were baked into a molten mass called a “crown”, which was then attached to a metal pole called a pontil. The pontil was mounted on hand-powered gears to spin the molten mass at high speeds, spreading the still-liquid glass by centrifugal force into wide, thin circles that were cooled and cut into individual panes. This became universally-known as Crown Glass. 

The spinning motion itself created the wavy ripple that characterized old glass, and also made certain imperfections. Where the spinning began at the pontil attachment had larger ripples and became known as the “bulls eye”. Air pockets were common as the shape of the molten glass change with exposure to sudden cooling. Both the bulls eye and air pockets were still cut into functional panes, typically mounted in lesser-viewed windows. One such window is on the North side of St. Michael’s church, where the imperfect panes are clearly visible. 

Another limitation of the old Crown glass-making was that the thin sheets became more brittle as larger sections were cut, leading to the preponderance of colonial “nine-over-nine” windows that feature so many individual panes.