Easy to Understand Glass Fusing Technical Terms

Have you seen some technical terms in glass fusing that you just don't understand?

Maybe you have heard the name of an item, but are not sure how it is used in glass fusing?

Or, you have a general idea what an item is, but need more information for your fused glass project.

Hopefully this page will help you to understand what these various 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 Temperature – This technical term is also known as the annealing point. It is the stress-relief point during the cooling phase of glass fusing.

Annealing Zone - The temperature, at the upper end of the annealing range. It is at located at the beginning of 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.

Bead Release – Used to coat mandrels when making a hole in glass.

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.

Bottle Cutter - A tool used to cut glass bottles.

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.

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

Canes - A string or rod of glass created by pulling and stretching molten glass from both ends.

Casting Glass - There are various ways to achieve casting glass. From melting frit to pouring hot molten glass into a mold to achieve a particular shape, each method is unique and different.

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

Chap Stick/Bees Wax - Used to protect marks that are made on glass. This protection will keep the mark in place when grinding or using a glass saw.

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 - Technical term for 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. Also referred to as shards.

Controller - The device on the kiln that helps control the temperature. It could be manual or digital.

Crash Cooling - The act of opening the kiln after firing to release heat and freeze the project to keep it from fusing further.

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.

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

Diamond Hand Pads - The most popular type of diamond polishing pads. A type of hand finishing tool that is used when the circumstances call for polishing by hand.

Dichroic Glass - This glass appears to be diverse colors when viewed from different angles.

Dichroic Coated Paper - The brand name for this product is DICRO-SLIDE™. It is also referred to as dichroic paper or dichroic slide. Add this to your plain glass to enhance it with dichroic.

Dust Mask – Technical term for a dust mask that 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. They are usually made from a metal alloy called Kanthal

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 Board – This material can be cut to make shelves, kiln posts, or molds. This material is ver versatile for creating projects in glass fusing.

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

Fiber Rope – Fiber rope is generally used to keep a space open when fusing glass.

Fine Silver Wire - This wire can withstand the temperatures inside the kiln. Once cleaned it 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 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 Fuse – Heating two or more pieces of glass until the slump and flow together to form one solid piece of glass.

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 Glues – 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 Molds – Molds that are used for the various glass casting techniques.

Glass Clay - Glass powder that is mixed with a binder and water to product clay.

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

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

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 Powder - 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.

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

Glass Sifter - Used to sort various sizes of frit or to dust glass with powder glass.

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

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.

Grozing – 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.

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

High Temperature 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.

Hot Casting - A type of casting where molten glass is poured into a mold.

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 Blanks - Jewelry that has a space to add a piece of fused glass.

Jewelry Findings - Everything you need for jewelry making.

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

Kemper Fluid Writer Pen – Used to write or draw on glass with a liquid medium.

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

Kiln Carving – Using ceramic fiber paper to imprint a design into glass.

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

Kiln Furniture – This term is generally referring to kiln posts, kiln shelf and other materials used inside the kiln to support or assist in the firing process.

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.

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.

Lost Wax Method - A glass casting process where wax is used to make a mold.

Mandrel - Used to maintain an opening in glass. This channel is usually for a necklace opening.

Millefiori - Tiny circles of glass used for embellishments.

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.

Morton System – A commercial line of glass cutting products.

Mosaic Tile Nippers – Used for cutting pieces of glass quickly. The shapes will not be straight or even.

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

Noodles - Long flat and broad pieces of glass. These look a lot like fettuccine. 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 Bar Slices - Thin slices cut off a pattern bar.

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

Pilot Pen - These pens are used to decorate or sign glass and will hold up during the 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.

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 – Technical term for stainless steel tools that are 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 Bricks - 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.

Ruling Pen - A ruling pen holds paint or ink in a slot between two flexible metal jaws.

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.

Sairset - This technical term refers to a material used in kiln building and to fix chipped or broken molds.

Sand Casting - Pouring molten glass into a mold made out of sand.

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. Also referred to as confetti.

Shelf Paper – Sometimes referred to as "Fire Paper" or "Shelf Release Paper" it is thinner than fiber paper and is used to protect glass from sticking to objects inside the kiln.

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 – Glass that has been placed over a mold and heated until the glass softens and conforms 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.

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.

Stained Glass Fusing - Fusing glass and using the pieces in a stained glass project.

Stainless Steel Molds - These can be purchased molds made for glass fusing, or metal bowls and other objects made out of stainless steel.

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.

Texture Pad - Earthenware molds that add texture to glass.

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.

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.

These technical terms and their definitions are recognized and taught by educators in the glass fusing field. This Technical Terms page is update as new information is found, or new technical terms are discovered.

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.

You can submit any Technical Terms to be added to this list by going to the Contact Me page.

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