A-Z List of Glassblowing Terminology [Updated]

Working the Flame is supported by its readers. We may earn commission at no extra cost to you if you buy through a link on this page. As an Amazon Associate we earn from qualifying purchases.

Glassblowing Terminology, Definitions & Phrases 2021 [Updated]

glassblowing terminology and phrases
Glassblowing terminology and phrases are unique to the craft and are important for all hobbyists to familiarize themselves with.

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.

Devardi Glass Lampworking, Blowing, Beadmaking COE 104 Beginner Starter Kit - Basic
  • Basic Lampwork Starter Kit for beginners. 2 hours of instructional video on DVD, plus full email...
  • (Requires disposable propane or Mapp Gas canister. or bulk tank propane with hose.)
  • Please use saftey lenses and adequate ventilation when lampworking.


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. 


One of the essential ingredients of glass, making up to 15-20% of the batch and consisting of sodium carbonate or potassium carbonate.


Slowly cooling a glass object to prevent stresses and cracking at a later date.


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.


Reheating blown glass at the glory hole to allow for inflation, manipulation, or fire polishing.


Silica, soda, potash, lime, or other raw materials that are melted down to form glass. 


A wooden paddle used to smooth the bottoms of glassware. 


Work station of a glassblower. 


Freshly gathered molten glass taken from the furnace.


A cooled glass object that still needs to be formed and decorated.


A hollowed out wooden tool that is dipped in water and used to form glass into a sphere.


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.


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.


Using tools or sandblasting to remove glass from the surface of an object. 


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. 


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.


Making a piece of glass narrower by pulling it.


Finely powdered glass and metallic oxide suspended in an oily medium used for decorating glass.


Making fine lines in glass that resemble feathers.


Forming, cracking off before annealing, cutting, enameling, and/or polishing a product  to complete it. 


Reheating an object while it is being worked. 


Burning apart pieces of rod or tubing using the heat of a flame. 


Spreading out the open end of a bottle or tube to create a wider opening.


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.


Senior member of a blowing team who directs the production of a project.


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.  


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.


Electric oven used for casting, fusing, and annealing.


A flat table on which glass is rolled to shape it and cool it. 


Forming a bottle neck by reducing an end of blown glass. 


Perforated work 


Layers of colored glass that cover each other, produced through casing or flashing. 


Smoothing a glass surface using a fin abrasive and hand tools.


Blob of glass used for decoration or in the place of a handle.


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.


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. 


Tiny gas bubbles that exist in groups. 


A main ingredient in glass, silicon dioxide. 


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. 


A defective object that is recycled.


Changes caused by a chemical reaction with the environment. 

Wetting off 

Using cold water to break a glass work off the blowpipe.


Supports the weight of the blowpipe while a glass work is in the glory hole.

Leave a Comment