Fused Glass Glossary

This fused glass glossary is a listing of some of the technical terms, items and processes used during glass fusing operations.

Many of the fused glass glossary definitions are linked to other pages where you will find additional information and ideas regarding kiln formed glass art.

The glossary also covers techniques and supplies used in jewelry making.

It is intended that this will be an expanding list of definitions so keep checking back for new information.


Annealing - At the end of the glass fusing process glass is cooled rapidly to reach the annealing point, stresses in the glass are relieved by holding the glass at a particular temperature for a set period of time. It is necessary to remove stresses otherwise the glass may break suddenly at some future time.

Annealing Point - The most efficient temperature point at which a piece of glass is annealed.

Annealing Zone - This is the temperature range beginning at the softening point and finishing at the strain point.

Aperture Pour - Glass is placed in a pot with a hole in the bottom. Melted at high temperature in a glass kiln, molten glass runs out of the hole make vivid circular patterns. Also known as a pot melt.

Art Glass-Used for stainless glass, mosaic and glass fusing. Art glass must be specially made for use as fusing glass.

Art Glass Tools - Techniques and tools used to alter, shape cut or drill cold glass.

Band Saw - Using narrow profile blades band saws can cut intricate patterns and shapes that would be impossible to do by hand. Roughly textured glass can be easily cut on a band saw.

Bat Wash - Is another name for kiln wash.

Bead Release - A compound applied to steel mandrels to prevent glass sticking to the mandrel. Used mainly by flame workers for bead making. Can be used during glass fusing to create holes in fusing projects.

Beetle Bits System - A glass cutting system designed for geometric and repetitive cutting.

Billet - A thick glass ingot used in kiln casting.

Blank - Is a solid bottom layer of glass on which other glass pieces are placed prior to the glass fusing process.

Blowing - Inflating a hot gather of glass attached to a blowpipe by blowing through the pipe.

Blowpipe - Usually about five feet long, this is an iron or steel pipe that is used for blowing glass. They have a mouthpiece at one end with a shape at the other end that helps retain the gather of glass.

BOROSILICATE GLASS - Is a dense glass that is harder than lime or lead glass. With a low co - efficiency of expansion it is used quite often by flameworkers making hand sculptured beads. Finished beads are best viewed in sunlight.

Bottle Cutter - Is a specialized tool used for the cutting of glass bottles.

Bracelet Molds - Stainless steel molds used for the bending of fused glass bracelets.

Break - Separating glass pieces after cutting, break occurs either by hand or with pliers.

Breaking Pliers - Designed to break glass cleanly along the score line.

Bubble Powder - A special powder used to create air bubbles between sheets of glass.

Bubble Squeeze - Squeezing air from between glass layers during the fusing process.

Burn Out - The removal of any contaminants by pre-firing the material in a vented kiln prior to fusing.

Carving - Altering the surface of glass by by sandblasting or using specialized hand or power tools.

Casting - Melting frit or glass pieces in a glass fusing mold or by pouring molten glass into a mold.

Ceramic Fiber - Made from spun fibers this is an insulating material used in glass fusing.

Cerium Oxide - Supplied in powder form and mixed with water for fine scratch removal and glass polishing. Will not remove deep scrathes.

Chap Stick/Bees Wax - Used to protect guide marks on glass when using water during grinding or saw cutting.

Circle Cutters - Glass circle cutters cut very accurate circles in fusing glass.

Cold Working - Techniques and tools used to alter, shape cut or drill cold glass.

Collar - A section added to a kiln to increase the overall height.

Combing - Carried out at high temperatures, a metal rod is drawn across the molten glass to create patterns.

Cold Combing Creating patterns in glass frit powder.

Compatibility- Glass that has the same or similar COE is said to be compatible. There should be an absence of stress when this glass is fused together.

Confetti - Glass confetti are very thin pieces of colored glass, which can be added to glass fusing projects.

Contour Fusing - Fusing glass without losing the basic overall shape.

Copper Oxide - A powder, which when added between pieces of fusing glass will produce turquoise colored bubbles following the fusing process.

Controller - A switch added to a kiln to enable the kiln to be switched on or off. Controllers usually have inbuilt settings to control the heating rate of the kiln. They may be either mechanical or digital.

Crash Cooling - Opening the kiln after fusing to allow a rapid cooling of the fused glass and to prevent further fusing.

Crucible - A special container used to hold glass whilst melting in a furnace or kiln.

Cutter's Mate - Top of the line glass cutting system.

Cutting Oil - A very light oil that is used sparingly to lubricate glass cutter wheels.

Decals - Glass fusing decals can be fused between or on top of fusing glass.

Devitrification - May appear on glass surfaces as glass cools. It is a scummy white or hazy, or rough surface on the fused glass. Some fusing glasses may be more subject to devitrification than others.

Devit Spray - Using an overspray can help prevent devitrification affecting the appearance of fused glass items.

Diamond Hand Pad - A popular type of hand polishing pad. These pads are coated with a diamond cutting surface and are ideally suited for hand polishing of glass.

Dichroic Glass - Originally from NASA as part of the space effort it is is a base glass coated with a special metallic coating. Once fused in a glass kiln amazing color shifts occur.

Dichroic Coated Paper - A special paper coated with dichroic which can be fused with glass in a glass kiln. Sold as DICHRO-SLIDE™ in glass supply stores.

Digital Controller - A programmable digital controller module is used to control glass kiln fusing schedules.

Dust Mask - A paper mask that provides some dust and fume protection during glass fusing operations.

E6000 Glue - Use this glue on fused glass to attach metal findings.

Edge Finishing - Tools and techniques for glass edge finishing.

Elements - Special wires inside the kiln that are heated by electricity and provide the heat required to carry out normal fusing procceses.

Embossing Stamps - Use embossing stamps to stamp designs into hot glass.

Enamel - Specially formulated enamel powder or paint suitable for glass fusing.

Engraving - To cut a pattern or design into glass. Can be done with a diamond wheel or bit, or other diamond surfaced tool.

Etching Dichroic Glass - Etching designs on dichroic glass with cream or an engraving tool.

Fiber Board - Usually 1/2" thick or larger and is used to make molds, kiln shelves or other kiln furniture.

Fiber Paper - A ceramic fiber used to protect kiln shelves and glass during the fusing process.

Fire Polishing - Glass is heated to round, polish or restore the edges of a piece that has been "cold worked" by grinding, drilling, sandblasting or sawing.

Firing Log - A written log of previous firing schedules and outcomes.

Flat Lap Grinder - A grinder for smoothing flat or long fused glass surfaces.

Frit - Made from crushed fusing glass and comes in a variety of sizes.

Frit Blends - Blends are made from combining complimentary frit colors together.

Frit Casting - Frit casting usually refers to glass frit melted in a mold.

Furniture - The shelves and posts used within a fusing kiln to support glass during the fusing process.

Fusing Bubbles - Problems arising from unwanted air bubbles appearing during the fusing process.

Full Fuse - Results in separate glass layers completely fusing into a single uniform layer with a smooth top layer with glass pieces being nicely rounded.

Fusing Glues - Hold items in place during the fused glass process with fusing glues.

Glass Clay - A mix of glass powder, binder and water that produces a moldable and fusible clay.

Glass Cracking - Glass cracking or breaking during or after the fusing process.

Glass Cutters - Special wheeled cutting tools are required to cut glass cleanly and accurately.

Glass Cutting - A glass cutter and the use of cutting techniques will produce clean and accurate scoring marks that will allow glass pieces to separate.

Gaffer Glass - Made by Gaffer Coloured Glass Co in New Zealand. High quality glass blowing and casting glasses are available.

Glass Grinder - A water cooled table top grinding machine used to clean up glass edges and to shape glass before or after glass fusing.

Glass Noodles - Use glass noodles to add a range of colors and shapes to designs.

Glassline Paper - Glassline paper is designed to be fired between sheets of fusible glass and is available in colored, plain and crinkled sheets.

Glassline Pens - Glassline pens are a painting and lining medium designed for glass fusing. They are lead free and food safe.

Glass Powders - Glass powders are made from finely ground glass which will add texture and color to fused glass items.

Glass Rods - Thick glass bead making rods are suitable for use in fused glass designs.

Glass Separator - Also known as kiln wash, shelf primer or glass separator, it is a refractory powder mixed with water and applied to kiln furniture to prevent hot fusing glass sticking to a kiln shelf or posts.

Glory Hole Furnace - This furnace is a special type of cylindrical hot flame glass furnace used by glass blowers, glass kiln workers and bead makers to heat and re-heat glass as they manipulate and shape it.

Grozing Pliers - Can be used as breaking pliers as well as nibbling away small pieces of glass.

Haik Brush - A soft brush available in various sizes and used to apply kiln wash to kiln shelves and molds.

Heat Resistant Gloves - Although glass fusing kilns are well insulated it is necessary to wear heat rated protective gloves when opening and closing kilns as as well as for handling hot objects.

High Temperature Wire - Can be fused between glass pieces or used to hold items in place whilst fusing.

Inclusions - Inclusions are objects fused between glass layers.

Infinite Control Switch - A rotary style control switch fitted to manually controlled glass Kilns. Kiln heat settings are set and adjusted with this control.

Iridescent Glass - Iridescent glass has a shimmering metallic coating.

Kiln Carving - Kiln carving is a process whereby a pattern is ‘carved’ into glass during the glass fusing process.

By placing an object between the kiln shelf and the bottom of the glass an impression of the object will be left in the glass.

Kiln Forming - Using a glass fusing kiln to heat, manipulate, alter or shape glass.

Kiln Wash - Used as a glass separator to prevent glass sticking to kiln shelves and other kiln furniture.

Lamp Working - Using a flame or torch to work with glass. Generally used to make glass beads.

Lava Cloth - Textured lava cloth is used to prevent glass sticking to kiln surfaces during glass fusing. The cloth leaves a textured finish on the glass.

Liquid Stringer - Liquid Stringer Medium is a special gel that is mixed with powdered frit or enamels enabling the mixture to be applied with a squeeze bottle or cake applicator.

Mandrels - Using a mandrel to create a hole or channel in fused glass.

Marver - Used in glass blowing and bead making this is a flat sheet of steel or graphite used to shape and cool the glass.

Mica - Mica powder and flakes are a mineral that can be used to create a wide range of metallic effects and sparkle to fused pieces of glass.

Millefiori - Made with various layers of color to form a flower like pattern for inclusion in fused glass projects.

Mold - May be made from refractory material and used for glass to slump or drape into or over the mold. Stainless steel molds are also used.

Morton Portable Glass Shop - This glass cutting system produces repetitive cuts and a large range of geometric shapes.

Pate de verre - A paste of frit or glass powder is placed in a mold and fused to form a fused glass object.

Pattern Bar - A pattern bar is a solid stack of fused glass strips which can be cut and added to glass projects.

Pattern Slices - Thin slices of glass cut from a pattern bar.

Pot Melt - Glass is placed in a pot with a hole in the bottom. Melted at high temperature in a glass kiln, molten glass runs out of the hole making vivid circular patterns. Also known as a an aperture pour.

Powder Vibe Tool - The powder vibe tool is used to add frit to fusing glass projects.

Pyrometer - A meter attached to a glass fusing kiln to monitor the interior kiln temperature.

Refractory - A material used for the interior construction of a glass kiln as well as molds and kiln furniture.

Respirators - Cartridge filter respirators provide a high level of protection against dust and fumes encountered in aglass fusing studio.

Ring Saw - These saws have a large rigid round diamond coated ring, which allows fusing glass to be cut in any direction. They can cut slightly tighter curves than a band saw.

Running Pliers - Can break thicker pieces of glass along the score line.

Safety Glasses - Approved clear safety glasses used when operating power tools and equipment, handling chemicals or hazardous liquids.

Sagging - Glass will begin to slump and sag under its own weight when it is heated to softening point.

Sandblaster - A sandblaster will remove blemishes, baked on kiln wash and devitrification from fused glass. Glass carving and etching may be applied with suitable sand blasting equipment.

Shaded Safety Glasses - Specially rated kiln safety glasses protect eyes from infrared radiation emitted by open hot glass kilns. Infrared radiation can cause cataracts in later life.

Shelf Paper - A special thin paper placed between glass and the kiln shelf to prevent the glass from sticking to the shelf.

Slumping- Slumping glass into a glass slumping mold

Soak - The period of time when glass is held at a specific temperature.

Softening Point - The exact point when heated glass, starts to soften and bend.

Strain Point - The lower end of the annealing zone, any stresses remaining in the glass are unlikely to be changed.

Stress - Tension left in the glass from incorrect annealing or incompatibility.

Stringers - Stringers are long thin glass rods,usually about 1.5 mm thick and available in a range of colors.

Thermocouple - A temperature sensing probe inserted into the kiln chamber and attached to the pyrometer to provide temperature readings.

Thermal Shock - Rapid temperature change due to uneven heating and cooling can cause glass to break.

Tile Saw - These saws are used for straight line cutting of fused glass. Will cut thick pieces of glass such as pattern bars and pot melts.

Volume Control - Glass volume control is a method of dealing with shape distortions that can occur during the glass fusing process.

Wheeled Glass Nippers - Small shapes and pieces can be cut with this tool.

Wet Belt Sander - Like other belt sanders it relies on an endless belt to provide a grinding surface for glass. Belts are easily changed and come in coarse, fine, ultra fine and cork for final polishing.

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