Glass is believed to have been created around 3000 BC, during the Bronze Age. There is archeological evidence that the Egyptians were familiar with Fused Glass techniques around 2000 BC. Fusing was the primary method of making small glass objects for approximately 2,000 years.
How glass is made has changed very little since it was first created. Glass is made from sand (65%), sodium carbonate (15%) and limestone (5%). The sodium carbonate and limestone make the glass more durable. An additional ingredient is to add color i.e., metallic oxide (cobalt for blue, chrome for green, manganese for purple, gold for pinks and roses, and erbium (rare) for pale pink). Yes gold and erbium, which is why pink glass is very expensive. If you are really curious to see how glass is made, bullseye (the manufacturer of the glass I use) has a fabulous video out explaining the art glass process. http://www.bullseyeglass.com/education/what-is-glass.html
For fusing purposes art glass is produced in the follow manner: sheet glass (for fused panels, plates, and for slumping), frits are ground grains of glass (powder, fine, medium and coarse) that can be used for casting, tapestry, or frit painting, rods and stringers (typically for Flameworking, however can be used in fusing as well), and billets (used for casting). As for me, I use sheet glass to make bowls, plates, etc., but I can also cut it up and use it for jewelry and as components for other techniques. I am also really starting to use frits (every size and color) for numerous fused glass techniques including frit painting, bowls, jewelry, etc. I bought some glass rods the other day and I am actually going to make a plate soon so we will see how that works out. I have never used billets; they are typically for larger casting projects.
Some of the key phrases I use in my fused glass descriptions are listed below:
Fused glass is glass that has been fired (heat-processed) in a kiln at a range of high temperatures (from 1,099°F to 1,501 F) until they bond. There are three main distinctions for temperature application and the resulting effect on the glass. Firing the glass at the higher spectrum of the temperature range 1350–1501 F is a “full fuse”.
Kiln is an oven used to heat and fuse glass.
Fire polishing is using the kiln to expose glass objects to significant heat so it assumes a smooth surface. Firing in the middle ranges temperatures 1251–1350°F is also considered “tack fusing”.
Casting is the generic name for techniques used to form glass in a mold.
Slumping (sagging / bending) is the process of reheating a formed glass blank, until it becomes soft and gradually assumes the shape of the mold. Firing in the lower ranges temperatures 1099–1251°F is used for slumping.
A mold is a form used for shaping and/ or decorating molten glass. Molds are used to give the object its final form by draping (over the mold), drop (through the mold), or slumping (into the mold). Most molds are now made of metal or ceramic.
Cold working is the collective term for several techniques to alter or decorate glass when the glass is cold. Some of the cold-working techniques include sandblasting, grinding, polishing etc.
Vitrograph is glass that is in a crucible that is heated to 1700 degrees and flows from a hole in the kiln floor in a stream of molten glass. It is used to make stringers and other abstract shapes that can then be used as components in other fusing projects
Flameworking/lampworking is the technique of forming objects from glass rods that, when heated in a flame, become soft and can be manipulated into the desired shape.
Hopefully this will help you understand some of the words I use in the descriptions of my fused glass artwork. Please let me know if you have any questions.
*The information above is from my experiences, the bullseye website, and wikapedia.