Glossary

Stained Glass Traditionally refers to glass that has had a stain applied to the surface which has been permanently fused with the glass by firing in a kiln. The term nowadays is taken by the general public to mean glass that is coloured in the manufacturing process. Some stained glass artists object to this, however when people that use non firing paint to decorate glass also call their work stained glass it is perhaps as well not to get too worked up . Life's too short.
Leaded Light An assemblage of small glass pieces held together by lead cames, their joints being soldered and the panel weatherproofed. Also a term used in the (double) glazing trade to mean a piece of glass to which stick-on lead has been applied. Have they no shame?
Came The H shaped strip of lead (or indeed brass or copper) into which pieces of glass are slotted to form a leaded light.
Heart The centre portion of a came. In engineering parlance equivalent to the web of a rolled steel joist section.
Mouthblown antique glass A glass made by the muffing process whereby a glob ( or gather) of molten glass is blown first into a large balloon and then into a cylinder, the ends are then removed (easier to say than to do) and the open ended cylinder is cut along its length and heated until it opens out flat. The most costly of glass and often the most beautiful, though not necessarily appropriate for period reproduction panels except in small amounts.
Cathedral glass Glass that is produced without blowing, but is completely transparent as opposed to opalescent.
Machine rolled glass Glass passed through rollers rather like an old fashioned mangle with one of the rollers being textured to produce glass that has a definite texture, in quite large sheets.
Hand Rolled glass Similar process to machine rolled but much more human effort employed, smaller sheets. Can produce effects like rippled glass, drapery glass etc.
Crown Glass Glass made by spinning a molten lump of glass until a disc as large as 4 feet in diameter was produced. Subsequently cut to make leaded lights, the flattest glass was reserved for the highest quality work.
Drawn Glass A process of making sheet glass by allowing molten glass to pass through a narrow slot under gravity.
Annealing The process removing stresses caused during manufacure by heating to softening temperature and allowing to cool at a controlled rate. Well annealed glass will cut predictably.
Opalescent glass Glass which is (usually) milky white and other colours. Not transparent though the degree of transparency can vary both in the single sheet and from glass to glass. Pioneered in USA by Tiffany for his windows and Kokomo Glass Co and others.
Norman Slab glass Glass made by blowing into a mould, usually cuboid and then split along edges. The centre of each piece so made is very much thicker than the outer portions.
Streaky Glass Two or more colours in a piece of glass that are deliberately not completely intermixed.
Flashed glass A particular type of mouthblown glass which involves two colours, one a very thin layer on top of a pale or clear background. Red glass has traditionally been made this was for centuries since the copper compounds used to produce red get darker and darker the longer they are heated so pot metal red glass can end up black. The colour of the final glass is controlled by the blower thinning down the red layer.
Pot metal A term referring to mouthblown glass that is the same all the way through, i.e. the glass is from the same pot.
Reamy Mouthblown glass that has not been smoothed out in the blowing process leaving wavy lines in the glass which distort the light.
Seedy Glass Glass that has a lot of air bubbles in it. Apparently seedy mouthblown antique was produced by putting a potato into the molten glass in the furnace to produce the air bubbles.
Bullion A large roundel, or the centre portion of disc of glass made by the spinning method or crown glass process. Was once considered to be the least desirable part of the disc (by people whose Holy Grail was the flattest glass possible, so they would have loved float glass then!).
Roundel A disc of spun glass up to about 150mm in size rather like the base of a wine glass. Used extensively in Victorian leaded panels as design elements. Also refers to a circular leaded panel.
Silver stain A blend of silver nitrate and binders which when mixed with water and brush applied to glass and then fired in a kiln, will turn the glass yellow.
Tracing stain A dense pigment used as a light block to create the line and definition of a painted piece of glass. Hand painted or silk screened on the glass and fired in a kiln it fuses with the glass surface.
Shading stain A less dense pigment used to create tone for shading in a painted piece of glass. Hand painted on the glass and then removed by various methods to lighten the effect before firing in a kiln.
Enamel A very finely powdered coloured glass used for creating colour on a piece of painted glass. The glass and enamel are fired in a kiln to fuse them.
Acid Etching The removal of parts of the surface of a piece of glass, usually flashed glass, to create two colour effects or shading on one piece of glass, by the use of hydrofluoric acid. Distinguishable from sand blasted glass by the clean cut i.e. the etched area is as polished as surrounding areas. If mixtures of acids are used then the etched area can be frosted.
Sand blasting Used to create decorative frosted patterns on the glass surface.
Slumping The process of raising the temperature of glass to it softening point and allowing it to deform under gravity into or onto a mould.
Fusing The process of raising the temperature of one or more pieces of glass to their melting point to allow them to combine. Can be used to combine metals, glass particles etc. for decorative effects.
Work hardening A loss of elasticity in a material caused by repeated strain. The loss of elasticity makes the material brittle and less able to withstand the normal strains put upon it whereupon it fails ie cracks.
Reinforcing bars Steel or brass round or rectangular bars fixed to a panel to provide support in both the horizontal plane and for very tall panels, the vertical plane. Traditionally fixed to the panel with copper wire ties. Often referred to as saddle bars.
Beading Strips of wood used to fix a panel into a wooden frame. Traditionally these were moulded, i.e. shaped.
Rebate The recess in a wood frame or door into which the glazing panel fits and is secured.
Putty Traditionally a mixture of linseed oil and powdered chalk used to seal the edge of a panel to its frame.
Brilliant Cut The process of cutting and polishing glass with abrasive compounds to make v shaped grooves. This is often employed to remove the coloured layer on flashed glass for decorative Victorian 'Glory Stars' and other pieces.
Leaded light cement A linseed oil based compound which is brushed into the lead on both sides of a new or rebuilt panel in order to fill the gap between the glass and the flanges of the lead. This seals and weatherproofs the panel and when hardened gives the panel its strength and rigidity. A very messy business.
Whiting Powdered chalk. Sold under the brand name of Snocal.
Tallow An animal fat used as a flux for soldering lead.