Glass Blowing

Glass Blowing

Glass blowing is the process of shaping glass by air pressure. Glass blowing is used to create glass bottles, studio glass, and scientific equipment such as test tubes. Glass blowing can be highly automated, as in the glass container industry, or it can be highly specialized, as in studio glass or scientific glassblowing.

Traditionally, three furnaces are used in glass blowing. The first, simply called the furnace, heats glass to temperatures up to over 2,000 degrees Fahrenheit. The second, called the Glory Hole, is not as hot as the furnace and is used to reheat the glass between steps. The third, called the annealer, is used to slowly cool the glass.

The process of creating glass containers is highly automated, but works in basically the same way as traditional glass-blowing, with fuel- or natural gas-powered furnaces operating at over 2,900 degrees Fahrenheit and complex forming machines handling the shaping of the molten glass. This process, like other forms of glassblowing, leaves the piece with internal stresses that need to be relieved through annealing. An annealing oven, sometimes called a Lehr, heats a piece of glass to 1,000 degrees Fahrenheit and then cools it over a period of about an hour.