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Glossary of Glassblowing Terms

A

Annealing: Annealing is the process of controlled cooling of hot glass objects to relieve internal stresses and prevent cracking.

Atmosphere: Atmosphere refers to the relative amounts of oxygen and fuel in a kiln. The atmosphere plays a crucial role in determining how glass behaves during the heating and forming processes.

B

Bench: The place where a glassblower works is the bench.

Blow Hose: A blow hose is a hose that a glassblower can position and blow into to put air inside of a bubble of glass while working with it.

Burner: A glassblower's heat source is called the burner.

C

Casing: Casing in glassblowing refers to the technique of applying one layer of glass over another. This method is primarily used to achieve a layered effect, which can enhance the visual appeal and complexity of the finished glass object.

COE: The coefficient of expansion (COE) is a measurement in glassblowing that describes how much a material will expand for each degree of temperature increase.

Compatibility: In the context of glassblowing, compatibility refers to the ability of different types of glass to be joined together while they're hot and remain that way without cracking when cooled.

Cracking Off: Cracking off is a technique used in glassblowing to detach a glass piece from the rod or pipe.

D

Devitrification: Devitrification is a problem that can occur during glassblowing in which the glass crystalizes improperly, creating brittle glass that lacks transparency. This phenomenon occurs when the glass is not properly cooled or is subjected to prolonged exposure to high temperatures.

Dichroic: Dichroic glass exhibits different coloration when viewed from different angles. This effect is achieved by adding metal oxides to the glass as it's made.

Didymium: Didymium is a type of glass used in safety glasses for glassblowers. The glass has a purple hue that blocks the bright yellow light given off when glass is heated, which can be bright enough to damage the glassblower's eyes.

Drawing: Drawing in the context of glassblowing refers to a technique where a piece of hot glass is elongated to make it narrower.

F

Flame-Annealing: Flame annealing is the process of annealing glass in a relatively low-temperature flame.

Flame-Cutting: Flame cutting, as the name suggests, is the process of using a flame to cut through an object, burning the two pieces apart.

Flameworking: Flameworking, also sometimes known as lampworking, is a glassworking technique that involves forming objects from rods and tubes of glass.

Flaring: Flaring is a technique used in glassworking where the open end of a bubble or tube is spread out to create a wider opening.

Frit: Ground-up bits of colored glass are called frit. Frit is applied to add colored detailing to a piece.

Fuming: Fuming is a technique used in glassworking in which a rod coated with a metal is inserted into the furnace along with a hot glass object. As the metal vaporizes in the heat, it permeates the glass, creating interesting colors or patterns when the glass cools.

G

Gather: In glassblowing, a gather is a lump of molten glass collected on the end of a rod.

Glass: Glass is a solid material formed from silica (silicon dioxide) and other additives, which are melted together at high temperatures and then cooled.

Graphite: Graphite is a form of carbon used to make glassblowing tools, as it's highly heat-resistant.

H

Hard Glass: Hard glass is another name for borosilicate glass, a type of glass that's highly resistant to thermal shock.

K

Kiln: A kiln is a specialized oven used for heating glass to high temperatures.

L

Lathe: A lathe is a specialized machine used to shape a piece of glass.

M

Mold: A mold is a form used to help shape glass.

O

Oxidizing: An oxidizing atmosphere is one that has a high oxygen content.

P

Paddle: A paddle is a common tool used to shape hot glass.

Point: A point is a piece of glass tubing that's tapered on both ends. This shape can be a starting point for glassblowing projects.

Pontil: A pontil is a metal rod used to handle and shape molten glass.

Preheating: In glasswork, preheating is required to bring a glass piece up to a temperature that's hot enough so that it can be introduced into the flame without cracking.

R

Reamer: A reamer in glassblowing is a specialized tool used to widen an opening in a piece of glass.

Reducing: A reducing atmosphere is one with a low oxygen content. Heating glass in a reducing atmosphere can induce different effects, like changes in opacity or color.

Regulator: A regulator is a device used in glassblowing to control the flow of gas to a torch.

S

Shears: Shears are specialized scissors used to trim and shape hot glass.

Sodium Flare: Sodium flare refers to the intense yellow light emitted when sodium atoms in glass are heated.

Strike: When a piece of glass strikes, that means that it changes color when it's re-heated.

T

Thermal Shock: Thermal shock is a condition in which a piece of glass is heated or cooled too quickly, causing uneven pressure within the material that leads to cracking.

V

Vermiculite: Vermiculite is a mineral that can be used to cool down a piece of glass. Surrounding the piece with this insulating material helps to draw down the heat gradually.

Additional Resources

• Glossary of Glass Terms
• Glass Terminology and Facts
• Glassblowing for Beginners: How to Get Started
• How Glassblowing Works
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• What's the Science of Glassblowing?
• The Ancient Art of Glassblowing and the Contemporary Artists Who Blow Us Away Today
• Glassblowing: A Complete Beginner's Guide
• Beginner's Glassblowing Guide: Tips and Techniques
• The Glassblowing Process
• Bulk Glass Bottles
• What Is Machine Glassblowing?
• What Is Scientific Glassblowing?
• Glassblowing Tools and Their Uses