HOME DIR EC TORY ARTI CLES BO OKSHOP WHA T' S ON Lead in Stained Glass Windows Integral Part or Disposable Commodity? Sebastian Strobl 'The leadwork of a window needs replacing after 100 years or so'. Everyone concerned with stained glass - makers and custodians alike - will have heard this remark at some point in their career, and all too many people still believe this statement to be correct, despite the fact that it is one of the most common misconceptions in the trade, and causes needless damage to historic works of art. So, why should releading take place at an artificially set date? Is it because 100 years is such a conveniently round figure, incidentally coinciding with the way we divide our calendar according to centuries? But what about quality of material, manufacturing process, design of the window or its location within the building? Examples of leadwork are known which disintegrated within years of their manufacture, while others are still fully functioning after more than 800 years of exposure to the elements. To get to the bottom of this myth, and to understand when action is needed to repair or relead a window, it will be necessary to take a closer look into the history of glazing in windows, into the changes in the manufacture of lead and, last but not least, into our own attitude towards this material. Figure 1: typical medieval and post medieval window lead profiles (Photo: Barry Knight) The use of lead in windows is to this day predominantly a characteristic of the western culture. Long before it was used as the means to facilitate the transferral of pictures onto glass, it served as the humble link between pieces of ordinary glass. For many centuries, glass suitable for window panes was severely restricted in size, and the only way to create larger windows was to piece together small sheets of glass. One way of doing this was to use of H-shaped rods of lead, called in Latin calamus, hence our modern term lead-calme or its more common version, lead-came. The versatility of the lead-cames resulted in the development of our stained glass windows as the cames are not only comparatively easy to produce, they are even easier to work. It is a straightforward process to form the cames along the lines of the design, to cut them with a knife and to solder the joints with tin. This is, of course, once the skills to do so are acquired. The panels created in this way are at the same time stable enough to withstand external impact such as wind pressure whilst still sufficiently flexible to allow movement of the glass under thermal expansion. We find the earliest reliable description of how the cames were made in the schedula 'De diversis artibus' ('On divers arts'), an unusually accurate compendium collated by the Benedictine monk Theophilus at the beginning of the 12th century. He describes how the moulds were made from pieces of timber, how the molten lead was poured into these moulds to cast the cames, and how the latter were subsequently scraped down to the required Historic Churches , 2002 Author Dr SEBASTIAN STROBL is a trained conservator and art historian, with a PhD on medieval glazing techniques. He is currently Head of Stained Glass Conservation at Canterbury Cathedral, and also a member of the Stained Glass Committee of the Council for the Care of Churches and Secretary of the International Technical Committee of the CVMA. Further information RELATED ARTICLES Stained glass Churches (general) RELATED PRODUCTS AND SERVICES Stained glass Decorative leadwork Glass protection Site Map © Cathedral Communications Limited 2010 Página 1 de 3 Lead in Stained Glass Windows 26/02/2011 http://www.buildingconservation.com/articles/leadstainedglass/lead_stained_glass.htm
