Window Glossary

Traditional window and leaded light / leaded window glossary

Old glass is a major contributor to the visual appeal of an older property and windows. With its rippled and irregular surface imperfections (such as seeds or bubbles) it gives the glass a vitality when light is reflected and contributes so much more to the character of a building. We’ve put much of the common terminology for traditional windows and glazing here.

  • Antique Glass – Generally refers to the process of flat glass production using the traditional mouth-blown method. The sheets produced are of modest size but are large enough for most restoration works.
  • Art Deco – a decorative and architectural style of the period 1925-1940, characterized by geometric designs and bold colours. Crittall Windows are strongly linked with this & modernist styles.
  • Came – Thin strips of lead, in an H-section used to hold small pieces of glass (historically called “quarrels”) usually diamond or square shaped.
  • Casement Window – Generic name for a window that has openers which are hung on hinges, at the side – usually metal or timber frames.
  • Cathedral or Rolled Glass – “Cathedral” is a rolled glass and started to be commercially available in 1830’s. Produced by pouring molten glass onto a metal or graphite table and immediately rolling it into a sheet using a large metal cylinder. The rolling can be done by hand or machine and can produce a very wide variety of colors and surface textures including hammered, rippled, seedy, and marine textures.
  • Crown Glass – Crown glass was an early type of window glass and relatively primitive. It was formed by twirling a sphere of molten glass into a disc. At the centre of the crown glass, a thick remnant of the original blown glass would remain, hence the name “bullseye.” First made in 1674, and until 1830’s.
  • Float Glass – A modern & standard technique since 1959, molten glass is poured onto molten tin to create an even, smooth and uniform finish.
  • Glazing Bars (also called Georgian Bars or Astragal) – Originally glazing bars of both sash and casement windows were abundant and thick. On the inside they were moulded to refract light and reduce glare. On the outside they were rebated to hold a glass pane, and generally glazed with putty as it is to this day (with traditional wooden or metal frames).
  • Horns – Small spurs of timber that project on a Sash Window – hanging down from the top sash and up from the bottom sash). Horns were introduced in the 19th Century to strengthen the joints.
  • Leaded Light – Leadlights or leaded lights are windows that are made of small sections of glass supported in lead cames, being held by the soldering of the lead joints and leaded light cement.
  • Muff, Cylinder or Broad Glass – Preceded Crown glass and was made by blowing a cylinder of molten glass, which was then cut along its side and flattened in a furnace, leading to seeds and bubbles.
  • Mullion – Vertical bar or pier made of masonry or timber that separate opening casements and/or “fixed” lights to cater for larger windows.
  • Quarrel/Quarry – A small pane of glass, usually diamond or square and which are used to construct a traditional “leaded light” panel.
  • Rebate – A rectangular recess along the edge of a timber [frame] designed to receive a shutter, door or window.
  • Saddle Bars – Also known as “Tie Bars” they are horizontal bars, traditionally made of Iron set into a window frame and to which the leaded light panel is tied – usually with Copper wire or sometimes lead.
  • Sash – In the first sash windows produced the top sash was fixed and the bottom sash slid upwards in a groove, held open in position by means of pegs or metal catches. In the late 17th Century a variant was introduced as we are familiar with today – the ‘double hung’ sliding sash window, with both upper and lower sashes hung on cords and counter-balanced by hidden weights.
  • Stained Glass – Traditionally this is glass that has had a stain applied to the surface and permanently fused with the glass by firing in a kiln. Panels constructed in the same way as traditional leaded lights.
  • Stanchion – An architectural term applied to upright iron bars in windows that pass through the saddle bars or horizontal irons to steady the leadlight.
  • Stay – A horizontal length of metal bar affixed to an opening casement and that attaches to the window frame to hold open.
  • Transom – A horizontal bar dividing a window into two or more “lights”.