Annealed (kiln) - Annealing is the process of slowly cooling glass in a temperature-controlled kiln to relieve internal stresses after it has been worked. Un-annealed glass will retain thermal stresses built up during the forming process which could cause the final piece to crack or shatter. Annealing glass is critical to its durability and longevity.
Bead Release - bead release is a substance used to coat the mandrels before glass is wound into them; it acts as a barrier between the glass and the metal so the beads can be taken off (released!) easily after they have been annealed. Dried bead release should be thoroughly cleaned from the bead before it reaches you, the buyer.
Borosillicate (boro) - Also known as 'hard glass' or Pyrex, Borosilicate glass has a higher melting temperature than other types of glass used for lampworking. Clear borosilicate glass is known for its clarity, while borosilicate colours have a unique and distinct palette. Usually, borosilicate colours are natural in shade and can change with the light. Borosilicate colours often really shine in natural light.
Bullseye - a US manufacturer of primarily fusing glass - classed as a COE 90, all of their glass is tested compatible and comes in a wide range of colours, textures and finishes. The company also produces rods for flame-working in a lot of the same colours as the fusing glass, and is again COE 90, as opposed to usual soda-lime lamp-working glass at 104.
Co-efficient of expansion (COE) - a number assigned to the different types of glasses which signifies the rate at which the glass expands. Mixing glasses with different COEs in the same piece can lead to compatibility issues.
Dichroic - often referred to as 'dichro' this word means two-coloured - it is glass that transmits (or allows through) one coloured light and reflects another. Modern day dichroic glass effects are achieved by a special coating process using metal oxides - this process was developed by NASA. In fusing, it can be fired with the coated side up, or capped with clear glass creating different effects. In lamp-working, it is usually encased.
Effetre - An Italian brand of COE 104 glass, most commonly used for making lampwork beads. Manufactured on the famous bead-making island of Murano.
Encasing - coating one colour of glass with another. Encasing is often used to describe the coating of a decorated or plain core of glass with clear glass. It can often seem to magnify the core.
Etched (glass) - etching is a process which alters the surface texture of glass, turning it from shiny to matte and frosted.Etched glass often resembles sea glass.
Float glass - a type of sheet glass. The technique was pioneered in the UK by Alistair Pilkington in the 1950s and involves floating molten glass on a bed of molten metal, usually tin - this gives a smooth finish and a consistent thickness desired for windows but which can also be used in glass art.
Frit - crushed glass often used as a decorative feature. When added to hot glass it produces a speckled or sprinkled effect.
Fusing (fused glass) - the process of heating glass in a kiln, up to a point to a point where it is molten - usually the consistency of honey - so that two or more layers will stick together and become one single piece of glass. Glass can be fused to different stages, from tack fusing where the glass is just stuck together and retain the squarish edges of the cut glass and layers will looked stacked, to full fusing where the edges are rounded off and layers will appear to be all in one.
Fuming - heating silver or gold in the flame so that the metal vaporizes or "fumes" microscopically thin layers of particles onto warm glass placed further back in the same flame.
Lampwork - Lampworking (also known as flameworking) uses a gas fuelled torch to melt rods and tubes of clear and coloured glass. Once melted, the glass is formed into beads and other glass objects using tools, hand movements, gravity and blowing.
Mandrels - Rods of stainless steel coated with bead release and used for winding glass onto to create beads. The size of the mandrel will dictate the size of the bead's hole.
Mica powder/pixie dust - a very fine powdered mineral which gives a subtle sheen or sparkle when applied to glass.
Murrini (canes) - small, intricately patterned pieces of glass that are used as decoration. Glass is built up in the flame in layers, which form an image or pattern when viewed in cross-section. This glass is then stretched until a thin rod (called the cane) is formed, and small pieces snipped off. It is these pieces which are placed as decoration into beads and glass.
Press - (noun) a tool which shapes hot glass by pressing in between its two halves. Results in a more uniform, standard shape.
Raised decoration (raised florals, dots) - decorative elements that aren't flush with the surface of the glass, similar to bas-relief. These may take the form of flower petals, pictures, dots or lines (see 'Bumpy beads)
Silver rich/reactive glass - glass specially formulated to react to temperature or flame atmosphere change to produce a range of colours, often metallic or iridescent.
Slumping - the process of heating glass in a kiln either over, or inside a mould so that it is just hot enough that it starts to sag under its own weight - it usually takes on the shape of the mould. There is not usually a change of thickness of the glass.
Stringer - a very thin rod of glass (often from 3mm thick to hair-thin) pulled from a thicker rod and used for decoration. Often used to draw lines and patterns.
Twistie - two or more colours of glass twisted together to form a striped spiral cane, used for decoration.