Easy to Understand Glass Fusing Technical Terms

Hopefully this page will help you to understand what these terms mean and how they relate to glass fusing. This page is a glass dictionary of terms and definitions listed.

These technical terms are listed alphabetically for easier reference. Browse through and get familiar with the terms of this hot craft.

Technical Terms

Annealing – The process of cooling a piece of glass to remove stress. This is done between the cooling of the glass from 1000° degrees Fahrenheit down to 600°degrees Fahrenheit.

Annealing Point - The temperature, at the upper end of the annealing range.

Annealing Zone - The temperature range beginning at the softening stage and ending at the strain point.

Art Glass - Colored glass used in glass fusing and stained glass. It may have certain properties required for fusing.

Bails – Arched hooplike pieces that are attached to glass pieces, allowing you to hang the glass piece on a chain or link it to another object.

Bent - Another term for slumped glass. When glass has been heated in a kiln so that it softens and slumps into or over an object

Blank - The bottom layer of glass on which other pieces of glass are placed before fusing.

Break – When glass separates and becomes two or more pieces.

Breaking Pliers – Used like your hands to break off glass at the score line.

Brittle Zone - Also referred to as the cold zone. This is from room temperature to about 900 degrees Fahrenheit.

Burn Out - Pre-firing material in a vented kiln to remove any undesired contaminants.

Cane - A string or rod of glass.

Cast Glass - Melting glass into a mold to provide shape and texture

Casting - Pouring hot molten glass into a mold to achieve that shape.

Ceramic Fiber Insulation - A refractory material that is made from spun fibers.

Circle Cutter - Scores ovals and circles on flat glass. It is easy to operate and has a suction cup that secures the cutter to the glass.

Cold Combing - The process of achieving the look of combing without working inside a hot kiln.

Cold Working – Working with or changing glass in its natural state. This could involve sanding, grinding, drilling, or sandblasting.

Combing - When a rake like tool is pulled across molten glass to create patterns.

Compatible - Glass is compatible if it has the same COE, and if after firing and annealing properly it remains relatively free from internal stress.

Confetti – Thin shard of glass used to add shading and design.

Controller - The switch on a kiln that allows you to turn it on or off, with different positions in between for heating rates.

Cutter - The technical term for this would be glass cutter. This is a tool consisting of a handle and a beveled cutting wheel.

Cutter Oil – A high-viscosity fluid used with a glass cutter. The oil keeps the wheel clean of dust and glass chips, which increases the life of the cutter.

Devitrification - A crystalline substance that appears as a foam or dull finish on the surface of some glasses when heated above 1000° F. This is caused by the glass going through a change in the texture from glassy to crystalline.

Devitrification Spray - This spray is applied to the surface of glass before firing to avoid devitrification and helps to give the piece a shiny exterior.

Dichroic Glass - This Technical term is derived from two Greek roots, "di" for two and "chroma" for color. So "dichroic" literally means "two-colored." This glass appears to be diverse colors when viewed from different angles. It is created by adding a thin layer of metallic oxides to glass. It transmits certain light wavelengths while reflecting others, causing an iridescent effect.

Dust Mask – Fits over your nose and mouth to protect you from breathing in harmful dust, or glass particles.

Elements - Wires inside the kiln that produce heat.

Enamels - This technical term refers to a paint made from finely ground glass and pigments that can be used to add color. Then they are fired on to the glass.

Fiber Paper – Thicker than thin shelf paper,used to protect the kiln shelf and for making channels in glass. Can be used many times.

Fine Silver Wire - This wire will shine up to bright silver after it is fused.

Fire Polishing Fused Glass - Heating glass to the point where the edges round and it has a shiny appearance.

Firing Log - Log of various firing schedules. Assists in understanding what has happened in past procedures.

Firing Schedule - Written details of the times and rates of heating and cooling during a particular cycle.

Fit - Compatible glass is said to "fit" each other.

Flash Glass - A piece of glass made up of a base layer with a thin separate layer of another color fused to the surface.

Flash Venting - Opening the kiln door or lid during the firing process to stop the process.

Float Glass – Commonly known as window glass. It has been created by flowing molten glass on a bed of hot tin. This causes it to have a shiny polished surface on both sides of the glass.

Fluid Zone - Also referred to as molten zone. Glass becomes fluid like and can flow. This occurs above 1350 degrees Fahrenheit. Fusing of the glass occurs around 1500 - 1600 degrees Fahrenheit.

Freeze and Fuse – The process of mixing powder glass and water in a flexible mold, freeze and then fired in a kiln. The technical term for this procedure is "pate-de-verre"

Frit – Glass that has been broken or ground into smaller pieces. It usually comes in different sizes, coarse, medium, fine, or powder.

Frit Casting - Filling a mold with frit and heating it until the frit fused into a solid mass.

Fritting/Sintering - The process of creating frit.

Full Fusing – Heating two or more pieces of glass until the melt and flow together.

Furniture - Ceramic posts used in a kiln for shelves or glass.

Fused Glass - This Technical term refers to specially designed glass that has been fused or melted together in a kiln.

Fusing Glass/Warm Glass - These technical terms refer to the heating of glass through the use of a kiln. This causes the glass to melt together into one piece of glass

Fusing Gloves - Gloves used to pick up hot glass and for opening up your kiln while it is in the fusing process.

Fusing Glue/GlasTac Glue/Elmer’s Glue – These technical terms are liquids used to hold glass pieces in place while transferring them from your work place to the kiln shelf.

Glass Casting - When you heat glass until it melts, and then it is poured into a mold.

Glass Cleaner - Any commercial ammonia-free glass cleaning product, soap and water or vinegar. Always use a lint-free towel when drying glass.

Glass Cutter - Used to score (scratch) the glass. See cutter above.

Glass Paints - Pigments, powdered or liquid glass paints applied to a glass surface

Glass Saw - Used to cut any glass shape out of any type of glass, quickly and with minimum glass waste.

Glassline Paints – Paints designed for applying color either between layers of glass or on top of glass.

Glass Compatibility – The technical term for making sure that every piece of your glass expands and contracts at the same temperature.

Gold Pen – Pre-filled pens for adding fine trim, detailed designs, enhancing and personalizing your glass.

Goggles - Used to protect your eyes while working with glass. Not used during firing techniques, will not protect against glare, ultraviolet and infrared radiation.

Grinder – Electrical tool that is used for the precision shaping of glass.

Grinding - Using an abrasive wheel on a grinder to smoother or shape the edges of glass.

Groze – The process of filing or chipping away small of glass.

Grozing Pliers – Used for chipping away small areas of glass. They have small serrated teeth.

Haik Brush – Used to apply shelf primer to kiln shelves and molds.

Hard Glass – A glass of high viscosity at elevated temperatures. Has a high softening point and is difficult to melt.

Hi-temp Wire – The technical term for this would be High temperature wire. Rated at 2000' Fahrenheit. High-temperature wire is sometimes used for making connections in fused glass jewelry. This wire will hold up to fusing temperatures, but will fire scale a bit and turn almost gray.

High Temperature Gloves - Safety gloves worn when hand are exposed to dangerous temperatures.

Hot Glass - Working with or manipulating glass while it is in a molten condition.

Inclusions - Any object fused between two layers of glass.

Iridescent - A surface treatment where a metallic oxide is bonded to the glass while the surface is hot. This causes the surface of glass to reflect a rainbow like color.

Jewelry Findings - Everything you need for jewelry making.

Jewelry Glue – For glass projects most people use E6000 or two part epoxy glue.

Kiln – Thermally insulated chambers, usually made out of fire bricks.

Kiln Forming – Using a kiln to heat and form glass.

Kiln Posts – These are put under your kiln shelf to raise it up. They are good for high temperatures have fluted sides and a hole in the center.

Kiln Shelf – These can come in different sizes and shapes and should be purchased to fit your kiln. They come in round, half round, rectangular, square, multi sided, hexagonal, octagonal, 10 sided and 12 sided. You place your items on this when you are going to fire them in the kiln.

Kiln Sitter - A devise that is set to automatically regulate the temperature inside a kiln.

Kiln Wash – This is a refractory powder that can be mixed with water and painted on kilns, kiln shelves and molds to prevent glass and accidental glaze drips from sticking.

Laminate - Using heat to bond glass to the point of just sticking together.

Liquid Stringer - A unique gel that you can mix with any brand or form of crushed glass, frits, powders or enamels before firing. It is a clean burning, water soluble binder.

Molds - Used for glass slumping, and fusing. They can be used to make jewelry, plates, bowls, etc. They come in a variety of shapes and sizes.

Needle Points - Sharp pieces on the edge of glass that are formed when the contracting glass sticks to parts of the kiln wash.

Morton Products – A commercial line of glass cutting products.

Mosaic Cutter – Used for cutting up thick pieces of glass.

Noodle - Long flat and broad pieces of glass. These look a lot like fettuccini. They can be broken into smaller pieces for decorations, and used as accents in fusing.

Painted Glass - Glass that has been painted with special paints then heated in a kiln hot enough to fuse the pigments into the glass.

Pate de Verre - Powdered glass is mixed with a liquid to form a paste and then spread or molded into a decorative design and fired in a kiln.

Pattern Bar - A bundle of glass that has been fused together to form a solid shape.

Pattern Slices - Thin slices cut off a pattern bar.

Peep Hole – A small opening in the kiln used for observation of glass during firing process.

Pliable Zone - Also referred to as the workable zone. Glass will begin to slump or move from about 1250 degrees Fahrenheit to 1350 degrees Fahrenheit. This is the zone where glass slumping occurs.

Powders - Glass that has been ground into a fine powder. It can be used to decorate glass before fusing, mixed with liquid stringer and used as paint, or mixed with water and used in the Freeze and Fuse method.

Prefire Adhesive - Glue that can be used to hold glass in place before firing.

Pyrometer - A high-temperature thermometer that measures the heat inside a kiln.

Ramp Time - The time required for the kiln temperature to increase or decrease. The amount of time stated in each step of a firing schedule for your kiln to go from its current temperature to the next indicated set point, in consistent degrees per minute.

Ramps - This term refers to the rapid heating cycles.

Reaching Tongs – Used to reach far into your kiln to put in or remove items. They are also great for picking up and working with hot items in the kiln. They have serrated tips that help in grabbing your item. These are made from stainless steel.

Refractory - This is high temperature brick that is used to construct ovens or kilns for melting glass.

Rigidizer - A chemical added to certain ceramic fibers to bind them into a solid state.

Ripple - The surface texture on glass. It usually consists of irregular bumps and valleys.

Rods - Cylindrical pencil-thick glass. They come in a wide range of colors and different COEs.

Run – When the glass begins to break at one edge and runs to the other edge.

Running Pliers – Used to control the breaking of glass. They are placed on the edge of the glass and when squeezed, the pressure causes the glass to break.

Safety Glasses - Safety glasses provide protection against glare, ultraviolet and infrared radiation. If they fit close to your face, they can be used during glass cutting.

Sagging Process – Heating glass until it sags and conforms to the shape of the form on which it rests.

Score Line – A light scratch on the surface of glass when the cutter is pressed against the glass and then drawn or pushed across the surface.

Seeds - Air bubbles that are trapped in glass during the manufacturing process.

Set Point - A goal temperature of the kiln in any given step of a firing schedule.

Shards - Glass that has been cut or broken from a sheet of glass.

Shelf Primer – Used to keep glass from sticking to kiln shelf. Sometimes called kiln wash.

Shotgun Annealing - The process of taking glass through different annealing points.

Side-firing Kiln - The elements have been placed around the sides of the inside of the kiln.

Slumped Glass – Placing glass piece over a mold and heating it causing the glass to slowly soften and conform to the shape.

Slumping – Heating glass and shaping it over or into a mold.

Soak - To hold the kiln at a steady temperature for a specific length of time.

Soak Time - The length of time to hold the temperature of the kiln at a certain set point or temperature before continuing to the next step.

Soft Shoe Brush – Used to clean your work surface after cutting glass.

Softening Point - The point at which glass when heated starts to soften and bend.

Stacking - The layering sheets of glass to create patterns or images.

Strain Point - This is the lowest annealing temperature. If there is any stress in the glass at this point, it is permanent.

Stress - The tension in glass that could cause it to break.

Stringers – Smaller thin round rods of glass that are approximately 1.5 mm thick. They look a lot like spaghetti. They can also be broken into smaller pieces and used for decoration or accents in fusing.

Tack Fusing - Fusing glass until it just sticks together. Each piece still retains its individual character.

Tested Compatible - Glass that has been tested and marked prior to sale to guarantee the compatibility with other glass with the same COE.

Texture Fire - Fusing glass to the point where it is bonded and the texture remains on the individual pieces.

Textured Glass - A rolled texture is imprinted on the glass as the sheet is being formed. A natural texture is created without mechanical inducing. A cold glass texture includes etching or any surface treatment performed on room temperature glass.

Thermal Shock - Breakage that occurs in glass because of rapid heating or cooling.

Thermocouple - The probe of a pyrometer. It is inserted into the kiln to measure the temperature.

Timer - Used to remind you to look at your piece of glass while firing. This clock needs to have an alarm.

Top Firing Kiln - The elements are placed in the lid of the kiln.

Transitional Zone - Glass begins to change from about 900 degrees Fahrenheit to 1250 degrees Fahrenheit. The strain point is at the lower end of this temperature, while the upper end is where the softening point and the annealing point are somewhere between.

Venting - The process of opening the kiln lid or door during the fusing process.

Viscosity - A liquid's internal resistance to flowing.

Vitrigraph - The act of maneuvering molten glass as it flow from the bottom of a raised and supported kiln.

Wedge Venting - Using a wedge of 1/2 inch to 1 inch to vent the kiln during firing.

Wet Felt - Soaking a ceramic-fiber with rigidizer and using it for mold making.

Wire Wrapping - The act of using wire to enhance a piece of artwork.

Wire Wrapping Tools - The use of tools to bind and twist wires together. Some of the tools used include pliers and wire cutters.

If you know of any other technical terms that you would like to see listed on this page, or some technical terms that you have any questions about, please let me know.

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