- Glass dates back some 3,500 years ago, making it one of the oldest art forms. Originally it was manipulated through a technique called core forming, meaning that glass vessels were created by wrapping hot glass around a clay base. However, around 50 B.C. the technique of glassblowing was invented. Through the discovery of glass blowing, glass became a household object throughout the Roman Empire, with glass being used for decoration inlaid with gold or as a vessel to store perfume.
- The No. 1 ingredient used in glass blowing is, of course, glass. Glass's base ingredient is silica, which is otherwise known as sand. However, silica alone has a very high melting point so glassblowers will mix it with metals and metal oxides, which help to lower the melting point and makes it easier to manipulate. In addition, to add color to the glass, a glassblower might add metal oxides. To get a deep blue-colored glass the glassblower would add cobalt to the mixture. Depending on the ingredient used, these can either make the glass appear more transparent or more opaque.
- The temperature at which the glassblower's mixture turns into glass is around 2,400 degrees Fahrenheit. However, the actual glassblowing is done at around 1,600-1,900 degrees Fahrenheit. A glassblower will use three different furnaces. The first is the furnace which contains a pot known as the "crucible," which holds the molten glass. The second furnace is referred to as the "glory hole" and is used to reheat glass pieces while they are being worked on, while the third is used to slowly cool down the glass piece. The glassblower uses a blowpipe, which is preheated and then dipped in the molten glass, and is used to gather the glass on the end of the blowpipe. The glassblower will then blow through the pipe to create a bubble in the glass. Additionally, glass can be added by dipping the blowpipe back in the furnace. The glassblower uses flat steel surfaces known as marvers to roll and shape the glass. The glass can also be shaped and manipulated using a variety of tools such as tweezers and a block and a jack (a shaping tool and a bladed tool).
- The third furnace is used for the final cool-down. It is more commonly called the annealer. If the glass were allowed to cool on its own, it can crystallize and crack. To prevent this, glassblowers cool down the glass through a controlled period. The temperature is monitored using a pyrometer while the glass cools over a long period of time. The time can vary depending on the dimensions of the glass piece. Once the piece is cool it enters the cold shop where it will be ground and polished as well as have any other decorative effects added such as glass etching.
- In addition to glassblowing there are several others forms of glass working techniques that are popular. Lamp workers use a blowtorch to melt and work the glass. Glass casting is another popular art form, in which the molten glass is poured into a mold. Glass cutting is yet another popular way of working with glass.
