Glass Blowing Process Explained

How is Glass Blown?

An Inside Look at the Glass Blowing Process

The talent required for the glass blowing process is not something that is easily learned and is certainly only perfected by the most intricate artists. The glass blowing process is depicted by the inflation of molten glass into a parson, or bubble, using a blow tube or a blowpipe. Around 50 B.C., the Phoenicians invented the glass blowing process in the vicinity of the Palestinian coast.

From the old city of Jerusalem comes the earliest evidence regarding the glass blowing process from a glass workshop. A collection of waste including glass rods, glass tubes and blown bottles were dumped in a ritual bath, dated from 37 to 4 B.C.

The Glass Blowing Process

A temperature of about 2,400 degrees Fahrenheit is required for the glass blowing process to take place. At this temperature, enough heat is emitted from the glass where it appears nearly white hot. The first step of the glass blowing process is to allow the bubble to rise and then the temperature is reduced to around 2,000 degrees Fahrenheit. During this stage of the glass blowing process, the material appears orange.

The glass blowing process involves the use of three furnaces, all of which serve different purposes. The first furnace holds a container of molten glass. The second furnace used in the glass blowing process is used for reheating a piece and is referred to as the “glory hole.” The third furnace, called the “annealer” is used for cooling the glass. Depending on the piece size, the cooling step in the glass blowing process can take anywhere from a a few days to several hours. This eliminates the opportunity for thermal stress to crack the glass.

To begin the actual glass blowing process, the blowpipe is preheated and then it is dipped into the molten glass that is in the furnace. After this, the glass is rolled onto the marver, which is a flat, thick sheet of steel. This step in the glass blowing process allows for the exterior to form a cool skin. A bubble is next created by blowing air into the pipe which develops into the piece.

Free-Blowing

This glass blowing process was introduced 20 centuries ago and is still commonly used. It is completed by blowing very abrupt puffs of air in the blowpipe that travels to the molten glass. The glass worker is then able to inflate the glass and work it into whatever shape is desired. A skilled worker using this glass blowing process can shape nearly any piece by controlling and swinging the pipe while they blow.

Mold-Blowing

This alternate glass blowing process involves using a molten glass glob that is placed at the bottom of the blowpipe. It is then inflated to fill up a metal or wooden carved mold. In this glass blowing process, the design is the result of the mold and not the glassblower.

Tools Used in the Glass Blowing Process

The primary tools that are used for the glass blowing process are the blowpipe, the punty, marver, bench, blocks, seers, paddles, jacks, paper, tweezers and sheers.

  • Blocks – These are ladle-like tools used in the glass blowing process that are made out of fruit wood that is soaked with water. They are used to cool and shape a piece.

  • Bench – This is the glassblower's workstation during the glass blowing process and allows a place to rest tools and sit down.

  • Jacks – The glass blowing process uses these tools that resemble giant tweezers. They are used near the end to finalize forming the creation.

  • Paddles – These are flat pieces of graphite or wood that are used in the glass blowing process for flat areas such as the bottom of the piece.

  • Tweezers – This tool simply pulls the glass or picks out any desired details.

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