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Fused Glass

Sometimes referred to as warm glass. Glass fusing and slumping are often referred to as warm glass, or glass art fusion. 


These firings range from 1100 degrees Fahrenheit to about 1700 degrees Fahrenheit. A kiln is used to make the glass molten and to join two or more pieces of glass. This process is also known as kiln-forming.

The art of fusing different glasses together can be used to create sculptures, jewelry, dishware, and other beautiful pieces. Despite the intricate appearance of fused glass, the process of fusing glass together is quite simple. With the right tools and safety gear (and a bit of practice) you can learn how to fuse glass into dazzling works of art.


Coldworking, as it sounds, is changing the shape or surface texture of glass using tools and processes that do not rely on heat. Coldworking methods include grinding, carving, engraving, polishing, sandblasting, and other techniques.

What happens to glass in the kiln?

When glass is heated, it softens and if more heat is applied, it begins to melt and flow. 

When two or more pieces of glass are heated together at first they will stick, or tack together. 

When heated further, they will melt together, flatten out, and become one solid piece of glass.

This solid piece can then be slumped into a mold. 

To read more about this procedure, check out the glass slumping process.

This will allow the glass to take on the shape of the mold and become a plate, bowl or just about any shape. 

You could also take a piece of glass and drape it over a mold.

There are many other types of manipulation that can be done in a kiln, like combing, fire polishing, glass casting, etc.

Slumping – Heating glass until it bends over or into a mold. 1200 to 1300 Fahrenheit.

Fire Polishing Fused Glass – Heating glass to give it a shiny appearance. 1300 to 1400 Fahrenheit.

Tack – Fusing two or more pieces of glass until the glass just sticks together, with each piece still keeping its own individual texture and character. 1350 to 1450 Fahrenheit.

Full – Joining two or more pieces of glass by heating until they melt together forming a flat rounded surface. 1450 to 1550 Fahrenheit.

Glass ovens heat single layers from the top, while ceramic units heat multiple layers from the side. 

Most glass projects are relatively flat, and with the heat radiating from the top, the entire face of the glass receives heat at the same time. 

This helps to keep the temperature differences within the glass uniform and helps to prevent cracking. 

You can still obtain these uniform heating results in a ceramic oven by slowing down the firing.



As glass heats up, it expands and when it cools down it contracts. 

The pace at which it expands can be measured. 

Distinct glass expands and contracts at various rates. 

These rates could have an affect on your artwork if using two dissimilar kinds of glass, each one melting at different temperatures and then each contracting at various rates.

Therefore it is important that your glass be compatible.

This rate of expansion is referred to as the Coefficient of Expansion which is abbreviated and called the COE of the glass.

Remember, all glass is not created equal and when heated and cooled the COE has to match or it will crack upon cooling.


Much like its humble cousin sandpaper, the diamond hand lap is used to make rough surfaces and sharp edges smooth. Unlike sandpaper, the abrasive surface of a hand lap is composed of bonded diamonds. This surface is attached to an ergonomic foam grip, making it a convenient and versatile coldworking tool that serves a number of functions in the kilnforming process. 

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