Glass Glossary

Helpful information

This is the controlled cooling of glass to minimise and reduce undesired stress.

Coefficient of expansion (CoE) of glass is the rate at which it expands when heated and contracts when cooled. It is therefore imperative that glass is compatible when completing any hot glass procedure.

Any sand blasting, engraving, grinding, cutting, or polishing of glass is known as cold working, these are all processes which can be done when the glass is “cold”, distinguishing it from fusing, casting, and Blowing which are all done hot.

Glass / colours that can be used together without creating excess residual stress are considered compatible, as they have the same or acceptable CoE. See also CoE.

A frosting or matte appearance can form on the surface of glass after fusing. This is devitrification and occurs when the normally random glass molecules become uniform and crystalise. There are several causes such as contaminants or incorrect firing schedule.

Dichroic glass is made by coating a sheet of glass with many layers of very thin metal sheets or metal oxides. This results in a surface that can display many different colours depending on whether light is reflected or transmitted from the surface. This coating can be applied to smooth or textured surfaces in blocks of colours or patterns. This results in each piece of dichroic being completely unique and a great choice for Jewellery.

Enamel pens or liquid glass pens are a squeezable bottle of coloured high fire enamel deposited through a fine tip, ideal for line drawing and intricate details. Once fired the effects can be stunning.

Frit is crushed glass which has been screened and cleaned to ensure consistent size and quality. It comes in all colours and various sizes Coarse, Medium, Fine.

The Technique of joining two or more pieces of glass by heat in a kiln.

Fusing glue is used as a temporary hold for fine / delicate pieces to avoid any accidental slipping or movement of components before or during firing. The glue is temporary and burns off cleanly when heated.

Glass bits are randomly shaped smashed sheet glass which has been fired to ensure all the edges are smooth and safe to handle. This is available in all colours.

Inclusions are items that can be fused between layers of glass. The inclusions can be metal foils, mica or glassline paper.

A kiln is a thermally insulated chamber used to heat and cool glass to pre set temperatures in a controlled manner, this enables processes to be completed such as fusing and casting.

Pâte-de-Verre is a kiln casting method that means “paste of glass”. It involves mixing frit granules with a binder, which results in interesting and unique pieces of work.

Sandblasting is using compressed air to project a stream of sand at your chosen surface, resulting in fine surface indentations altering the finish to a opaque frosted effect.

Slumping is to heat glass sufficiently so that it bends under its own weight, taking the shape of the mould on which, it rests.

Internal force or tension within a piece of glass. Causes of stress can be incompatibility or incorrect annealing.

Some coloured glasses can appear pale or colourless in the cold sheet form, but they can “strike” or mature to a very different colour when fired.

Stringers are threads of glass pulled from re-melted glass sheet. They come in all colours and several different diameters. They are ideal for creating lines on a piece.

Tack fusing is a technique in which pieces of glass are heated until they are just hot enough to stick together and retain much of their original textures and characteristics.