York Glaziers Trust - Illustrated Glossary

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York Glaziers Trust is the oldest and largest specialist stained glass conservation studio in Britain. YGT is a charitable trust dedicated to the care and conservation of historic stained glass in York Minster and throughout the UK. Discover more

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Illustrated Glossary

To help you understand the medium of stained glass better, here is an illustrated Glossary:

Abrade

To grind away the coloured upper surface of a flashedglass, revealing the base glass beneath. Tell-tale scratches left by the grinding tool will often remain around the edges of the abraded area. This technique is most commonly found in the context of flashed ruby glass.

Armature

A shaped iron framework inserted into a lancet window-opening to provide support for panels of stained glass. Armatures were used until the late thirteenth century

Back-Painting

Painting applied to the exterior surface of the glass.

Badger

A broad brush, traditionally made of badger hair, used to spread glass paint evenly across the glass.

Bull's Eye

The raised knob of glass marking the point at which the pontil iron was formerly attached to the centre of a crown of glass. These thickened pieces are usually cut off and discarded, although in the interest of economy they were sometimes used for decorative effect in less expensive secular or domestic settings.

Calmes or Cames

From the Latin calamus, meaning a read. Cast strips of lead, H-shaped in section and cut to the requisite length, were used to hold glass pieces together in the assembly of a stained glass panel. The centre of the lead is called the heart, while the overlapping areas that cover the glass edges are called the flange or leaf. From the end of the 16^th century onwards calmes were milled rather than cast. Milled lead often reveals the marks of the teeth of the lead mill on the heart which can sometimes be inscribed with names and dates. Leads are soldered at the intersections in order to make the panels rigid and strong.

Cartoon

The full-size outline drawing from which a stained glass panels is made. For much of the medieval period the cartoon was drawn out on a whitened table and was not, therefore, preserved at full size. Only in the 17^th century were cartoons marked out on paper, meaning that they could more easily be stored and retained for adaptation and reuse.

Corrosion

The deterioration of the glass surface, usually the result of chemical decomposition of the base glass brought about by exposure to moisture. The process can manifest itself in pitting or crusting of the surface and will eventually reduce the thickness of the glass and/or result in holes. Any surface decoration is lost as a result.

Cross-Hatching

A network of fine intersecting painted lines used to model or shade areas of a design.

Crown Glass

Made by spinning an opened-up cylinder of glass still attached to the pontil iron, so that centrifugal forces open and flatten the glass into a circular sheet.

Diaper

A repeated geometrical pattern used to decorate a background or drapery etc

Enamel

A coloured painting pigment made from a metallic oxide colour mixed with a flux of molten glass. This can be fired to the interior surface of an uncoloured base glass, allowing a multi-coloured painterly effect, comparable to the application of paint to a canvas.

Ferramenta

The general term denoting the range of ironwork set into the masonry of a window to provide support for stained glass panels (see also armature,stanchion, lug-bar, T-bar).

Flashed Glass

A coloured glass made by the application of a thin layer of coloured glass to a base glass of another colour (most commonly uncoloured) during the blowing of a sheet. The flashed upper surface can either be ground way (abraded) or removed with acid (acid-etched) to create complex decorative effects. This is most commonly found as red on an uncoloured base (flashed ruby).

Glass Paint

A mixture of finely ground glass, iron or copper oxide, and a flux. When mixed with a binding medium and diluted to a range of consistencies, the paint can be applied and then fired to the glass surface.

Grozing Iron

The flat, grooved metal tool used to cut and shape glass throughout the medieval period. Glass cut with a grozing iron has a distinctive 'nibbled' and chamfered edge.

Lug Bar

A flat, slotted support bar to which stained glass panels are attached using a wedge of metal.

Matte

An even, overall wash of glass paint.

Muff

A large cylinder of blown glass, cut along its length while still hot and flattened to form a sheet from which stained glass can be made.

Murrey

A glass colour ranging from purple to browny-pink.

Pitting

The phenomenon of small craters or cavities in the surface of glass, caused by the process of corrosion.

Plating

The doubling up of glass by the attachment of an additional layer, held within a single lead. This can be an artistic technique used as a means of modifying or intensifying colour, or can be used as a protective measure during conservation.

Pot-Metal

Glass coloured throughout its thickness when molten (i.e. in the 'pot') with the addition of one or more metallic oxides.

Quarry

From the French carré, meaning square. A small pane of glass, usually diamond-shaped but also rectangular or square. Quarries can be plain or painted with a decorative motif.

Rinceau

A foliate design used to decorate background or drapery.

Roundel

A general term used to denote a unipartite panel, usually circular, but sometimes oval or even rectangular, bearing a self-contained design.

Ruby

Red glass, usually made by flashing red glass onto an uncoloured base glass. An unflashed red glass would appear opaque when held to the light.

Saddle Bar (or Tie Bar)

A bar set horizontally into the masonry of the window opening to which stained glass panels are tied with lead or copper ties, preventing panels from flexing out of the vertical plane.

Sanguine

An iron-based painting pigment, first introduced in the 16th century, that turns pink to red-brown after firing.

Silver Stain (or Yellow Stain)

A surface stain produced by the application of a silver compound to base glass. When fired the stain turns yellow, ranging in hue form pale lemon to dark orange. It is normally applied to the exterior surface of the glass. Introduced into stained glass repertoire only in the early 14^th century.

Smear Shading

An application of thin paint to the glass.

Stanchion

The vertical support bar set into the masonry, internally or externally (or both). In some cases the stanchion passes through a lug in the horizontal saddle bar.

Stick Work

Also called needle work or scratching out. The technique of picking out a design or detail from a layer of glass paint, allowing light and colour to show through. A variety of fine pointed tools were used, including needles, pointed sticks or the end of the paint brush.

Stipple or Stipple Shading

A method of modelling achieved by dabbing the wet surface of unfired glass paint, usually with the bristles of a dry brush.

T-Bar

T-shaped in section, set horizontally into the masonry of a window opening at the divisions between stained glass panels, each bar supporting the weight of the panel above.

Trace Line

A strong line of paint, delineating the main lines of a design.

Tracery

The stone elements used to subdivide a window opening, a characteristic of window design from the second half of the 13th century onwards. When applied to the stained glass in a window, the term refers to the smaller, more elaborately shaped openings at the head of the window.