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Glass Fusing Terms
The following list are some of the common terms you may come across relating to glass fusing and our attempt to explain their meanings.
Anneal: The process of cooling the glass in a controlled manner to reduce internal stress between different pieces of glass caused by the expansion and contraction associated with heating and cooling. Bring the fused piece back to room temperature without breaking.
Annealing range: The temperature range where annealing takes place in a fused glass piece.
Base glass: The bottom layer of glass in a fused glass piece.
Coefficient of expansion (COE): The rate at which a material (glass) expands when it is heated. There are kinds of glass made specifically for fusing so that they all have a similar COE.
Cold working: Glass working techniques that do not involve heat like sandblasting, and polishing the glass.
Combing: also called Raking, is done when the glass is heated to around 1650 degrees and a tool is "raked" through the glass creating a pulled pattern.
Compatibility: Glasses that have the same COE are considered compatible with one another, meaning they can be fused together without introducing to much stress between the pieces.
Confetti: Very thin blown glass shards that can be fused with other glass to make a design.
Devitrification: Crystallizing of the surface of the glass.
Dichroic: Glass with a thin metallic layer on the surface which allows light to reflect one color and transmit another.
Firing schedule: The heating and cooling rates associated with making a fused glass project.
Frit: Glass that has been ground or crushed. It is available in different sizes.
Full fuse: The point at which all of the pieces in a fused project melt to form a single smooth surface.
Initial heat: The first stage or ramp of a firing schedule.
Kiln: An enclosed oven that is capable of reaching sufficient temperature to melt glass.
Kiln shelf: A flat removable ceramic surface used in a kiln.
Mold: Any form used to melt glass into, over, or through.
Pattern bar: Glass that has been fused together in a bar form to be sliced on a wet saw and used as design elements.
Pot melt: A technique where you fill a crucible or ceramic pot that has a hole in the bottom with glass. Put it in a kiln raised above the kiln shelf and heat it so the glass melts and runs out through the hole. It swirls out of the hole and mixes the different glasses into a small sheet on the shelf.
Powder: Very finely ground glass.
Ramp: The rate at which a kiln is set to heat or cool on a particular segment of a firing schedule.
Rapid cool: When a fused glass project is cooled from fusing temperatures to the annealing temperature.
Rods: Glass that has been pulled into a rod like shape.
Sagging: Bending glass in a kiln or with a torch.
Screen melt: Similar to a pot melt described above only the glass is placed on a metal screen and heated to melt through to the kiln shelf mixing together.
Shelf paper: A ceramic fiber paper used to keep glass from sticking to the kiln shelf
Shelf primer: Also called kiln wash is a mixture of finely ground ceramic materials that are mixed with water and painted on a kiln shelf or mold to keep the glass from sticking during firing.
Slumping: Bending glass into a mold
Stringers: Very small glass rods, usually 1/16" across or less.
Strip construction: A technique using thin strips cut from sheet glass and laid on end to create a pattern that is then fused together.
Tack fuse: Fusing glass together at the lowest possible temperature so the pieces keep their character and don't all melt into one smooth surface.
Thermal shock: Breaking of the glass due to heating or cooling it to rapidly.
Vitrograph: A bottom draw glass furnace. Glass is melted in the furnace and gravity feeds it out the bottom where it can be manipulated.
This is by no means an exhaustive list, but covers a lot of the basic terms associated with glass fusing.