Glassblowing Terminology, Definitions & Phrases 2021 [Updated]
Glassblowing is a traditional art form that involves many specialized techniques and tools.
Those who are new to glassblowing may feel overwhelmed at first by the intricacies of the craft, but knowing key terminology and phrases can encourage higher confidence and a deeper understanding of the glassblowing process.
Whether you are a brand new hobbyist, a seasoned professional, or are just curious about learning the basics of glassblowing, this list of glassblowing terminology, definitions, and phrases will be beneficial in deepening your knowledge of the art form.
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Abrasion
Creating shallow decorations by grinding glass with a wheel.
Acid Etching
Creating decoration on the surface of glass through the use of hydrofluoric acid.
Acid Polishing
Established in the 19th century, this technique involves dipping a glass into a mixture of hydrofluoric acid and sulfuric acid to create a glossy surface.
Air Trap
An air-filled void that can be any shape but is frequently tear-shaped, elongated, or twisted when located in glass stems.
Alkali
One of the essential ingredients of glass, making up to 15-20% of the batch and consisting of sodium carbonate or potassium carbonate.
Annealing
Slowly cooling a glass object to prevent stresses and cracking at a later date.
Applique
Hot glass bits that are attached to the surface of glass for decoration.
Art Glass
Ornamental glassware, glass created with new textures, colors, and casing.
At-the-fire
Reheating blown glass at the glory hole to allow for inflation, manipulation, or fire polishing.
Batch
Silica, soda, potash, lime, or other raw materials that are melted down to form glass.
Battledore
A wooden paddle used to smooth the bottoms of glassware.
Bench
Work station of a glassblower.
Bit
Freshly gathered molten glass taken from the furnace.
Blank
A cooled glass object that still needs to be formed and decorated.
Block
A hollowed out wooden tool that is dipped in water and used to form glass into a sphere.
Blowing
The process of forming glass by inflating the molten glass on the end of the blowpipe. Air is blown through the pipe to inflate the glass.
Blowpipe
The iron or steel tube used to blow air into hot glass. Usually 4-5 feet long.
Borosilicate Glass
First created in 1882, this glass has boric acid flux instead of alkali, making it more resistant to quick changes in temperature.
Carving
Using tools or sandblasting to remove glass from the surface of an object.
Casting
Forming glass in a mold by paving molten glass into a sand mold or placing a mold in a kiln.
Cold Working
Altering and decorating glass when cold through the use of cutting, copper-wheel engraving, and other techniques.
Collar
A band of glass that forms the rim of some vessels like bottles.
Copper-wheel Engraving
Decorating a glass object through the use of copper disks rotating on a spindle.
Drawing
Making a piece of glass narrower by pulling it.
Enamel
Finely powdered glass and metallic oxide suspended in an oily medium used for decorating glass.
Feathering
Making fine lines in glass that resemble feathers.
Finishing
Forming, cracking off before annealing, cutting, enameling, and/or polishing a product to complete it.
Firing
Reheating an object while it is being worked.
Flame-cutting
Burning apart pieces of rod or tubing using the heat of a flame.
Flaring
Spreading out the open end of a bottle or tube to create a wider opening.
Fluting
Vertical lines or grooves that act as decoration in glass.
Folded Rim
A glass rim that is extra strong due to being doubled in thickness.
Gaffer
Senior member of a blowing team who directs the production of a project.
Gather
Molten glass collected on a rod or punty.
Glory Hole
The opening of a furnace.
Hydrofluoric Acid
Corrosive acid that creates a polished surface on glass.
Iridescence
Created by introducing metallic substances into a batch, or by applying stannous or lead chloride, a rainbow effect that changes depending on the angle it is viewed.
Kiln
Electric oven used for casting, fusing, and annealing.
Marver
A flat table on which glass is rolled to shape it and cool it.
Necking
Forming a bottle neck by reducing an end of blown glass.
Openwork
Perforated work
Overlay
Layers of colored glass that cover each other, produced through casing or flashing.
Polishing
Smoothing a glass surface using a fin abrasive and hand tools.
Prunt
Blob of glass used for decoration or in the place of a handle.
Punty
Solid metal rod that holds an object after it is removed from a blowpipe.
Reverse Painting
Applying paint to the back of an object to be viewed from the front. Pigments are applied in reverse order.
Ringer
A glass worker who applies rings to large pieces of glass.
Seam mark
A thin ridge in glass that shows it was made in a mold.
Seeds
Tiny gas bubbles that exist in groups.
Silica
A main ingredient in glass, silicon dioxide.
Stemware
Name for drink ware and dishes that have a stem supporting the bowl.
Studio Glass
Glass products made in a studio instead of a factory, therefore unique in style or limited in their quantity.
Thermal Shock
Strain created when heating or cooling glass abruptly.
Waster
A defective object that is recycled.
Weathering
Changes caused by a chemical reaction with the environment.
Wetting off
Using cold water to break a glass work off the blowpipe.
Yoke
Supports the weight of the blowpipe while a glass work is in the glory hole.