The next time you watch the clouds floating past your window, you might want to consider the fact that the privilege of doing so was a few thousand years in the making.
According to legend, glass was discovered when soda ash merchants were shipwrecked in Phoenicia. They supposedly used lumps of their wares to prop up their cooking pots, and when the sand melted, and voila, glass was born. Although this makes for an entertaining tale, historical evidence shows that glass was actually first made in Mesopotamia around 2500 BCE.
For the next thousand years or so, glass was mainly used for trinkets like beads and seals before any practical applications evolved. Tableware was the primary use for glass for quite a span of time. The Roman poet Propertius noted that the glass dinnerware was, "especially good for summer banqueting."
Vessels of all description flourished as glass production techniques were honed around 1500 BCE. At first, glass items were formed around a clay core. Later, molds were employed. Around 50 BCE, the discovery of free-blowing techniques revolutionized the art form. Glassblowing techniques created during this time would remain relatively unchanged thought the ages.
Finally, another use for glass was discovered. Glazed windows became commonplace in Rome in the first century CE. Although they let in light while keeping out the elements, that early version was rather thick and it couldn't be seen through clearly. Medieval glass blowers eventually started making crown glass, which was spun out from a central point that left a sort of belly button effect in the center of the pane. Windows made from this glass were also not very easy to see through.
In the late 1700s, plate glass finally came into being. The process was developed in which the glass was poured out into a mold before it was ground and polished by hand, which was an expensive proposition.
It wouldn't be until the early 1800s that technology advanced to the point where the molten glass could be rolled out in a continuous, smooth sheet. Technological advances continued to mechanize the glass making process. In 1902, the sheet glass drawing machine was invented by Irving Colburn. Window glass could now be mass produced. Further innovation came in 1959 when Sir Alastair Pilkington introduced float glass production. Nearly 90% of flat glass is still manufactured in this manner.
Although glass is now available in any number of varieties, it's interesting to note what a long road it took to allow people to gaze though its panes.
by Linda Childers