Jewels of Light: Creation, Preservation, Appreciation of Stained Glass

Elizabeth Dent, who holds an MA in Stained Glass Conservation & Heritage Management from the University of York, where she was a Samuel H. Kress Fellow, and now works within the Office of the Director at the National Gallery of Art, Washington, reviews the International Symposium on Technical Aspects of Stained Glass, held at Washington National Cathedral, Washington DC, 19–20 June 2015.

On 19–20 June, Washington National Cathedral in Washington DC hosted an international symposium on the technical aspects of stained glass, organized by the Association for Preservation Technology. Featuring speakers from Canada, the UK, and the USA, the symposium covered a wide range of issues related to the conservation and understanding of stained glass. A round-table discussion on stained glass standards led to important initial decisions regarding guidelines and accreditations for American conservators, and marked a shift towards raising the profile of the medium in the USA and reconsidering its conservation within the broader context of historic preservation.

Fig. 1. Jean Parker Phifer (c) Elizabeth Dent.

Fig. 1. Jean Parker Phifer (c) Elizabeth Dent.

The symposium opened with an introduction to Washington National Cathedral by James Shepherd, Director of Preservation and Facilities. Shepherd provided a history of the cathedral, and focused on the ongoing campaign to repair extensive damage caused by the 2011 Washington earthquake, including stained-glass projects. He emphasized the importance of educating repair and maintenance workers, citing the positive effects visible among staff that underwent an educational course on the history and significance of the cathedral and its fabric. This focus on education and collaboration amongst the various groups responsible for the care and treatment of stained glass was a recurring theme throughout the symposium.

Sarah Brown (Director of the York Glaziers Trust and course director of the MA in Stained Glass Conservation & Heritage Management at the University of York) was a keynote speaker. Brown provided a European perspective on stained-glass repair and conservation practices from the twelfth century to the present. This extensive overview was of particular interest to the audience, as the management of North America’s stained glass heritage is a comparatively recent discipline. In tracing stained-glass repair through the centuries, Brown discussed the development of conservation theory and ethics, which led to the need for a code of practice. She detailed the post-Second World War period, with the creation of the Corpus Vitrearum, and the important milestones in CVMA research, including the development of its guidelines, knowledge of the impact of environmental factors on stained glass, and effective isothermal glazing, a practice that was an important focus of the symposium.

A detailed overview of isothermal glazing was provided by Arthur Femenella Jr (of Femenella & Associates), with special reference to his stained-glass conservation project at the nineteenth-century Old South Church in Boston. The implementation of isothermal glazing at the church allowed historic lead networks to be retained and the glass to be protected for the future. With the concept of isothermal glazing remaining less known in the USA, Femenella’s presentation left the audience with a clear understanding of the advantages of protective isothermal-glazing systems, underscoring the need to further raise awareness.

Isothermal glazing is a cause for which the second keynote speaker, Keith Barley MBE (of Barley Studios) is a leader in the British conservation community. Barley spoke of his decades of research on isothermal glazing, and stressed that it is a practical system that can be implemented by all glaziers – an important consideration for the symposium audience. Barley addressed the importance of isothermal glazing, which allows conservators to retain historic lead, and protect glass from damaging external factors, condensation, and moisture. He discussed the implementation of isothermal glazing in his recently completed conservation of the sixteenth-century Herkenrode glazing at Lichfield Cathedral, and shared innovative techniques employed in the project, including cold painting on the reverse side of original glass and the reduction of mending leads without their removal. These new techniques were explored with success in the project, while maintaining minimum intervention in the treatment of this important sixteenth-century glass.

New technologies employed in the conservation of stained glass at St Patrick’s Cathedral in New York City were presented by Jean Parker Phifer (Consulting Restoration Architect to Murphy Burnham & Buttrick) and Drew Anderson (Conservator at the Metropolitan Museum of Art). An innovative approach to the surveying and documentation of this nineteenth-century glazing scheme was undertaken for the project, with the use of the BIM360 Field program on iPads. Photographs of the windows were uploaded onto iPads in advance, allowing for the glass to be surveyed with the image on the screen, and digital annotations and markings of condition made on site, directly on the image. After surveying the glass, necessary in situ and studio conservation work was carried out by Botti Studios, and the BIM 360 database updated to reflect completed work. Because the cathedral featured an early example of unvented protective glazing, a process of isothermal venting, in which targeted pieces of glass were removed and reinserted as baffles, was undertaken, allowing for the circulation of air in the interspace. The presentation demonstrated the important role technology can play in stained-glass conservation, and the positive results of strong collaboration between architects and conservators.

Fig. 2. 'Round table' discussion (c) Elizabeth Dent..

Fig. 2. ‘Round table’ discussion (c) Elizabeth Dent.

The round-table discussion, moderated by Arthur Femenella Sr (of Femenella & Associates), Stephen Hartley (of Savannah Technical College), Keith Barley, Sarah Brown, and James Shepherd, resulted in a lively and productive debate over standards, guidelines, and accreditation processes for stained-glass conservation in the USA. The outcomes of the discussion were that the CVMA guidelines were sufficient, that they lack marketing and distribution within the USA stained-glass community, and that awareness must be raised in the future. It was also accepted that an accreditation process for stained-glass conservators in the USA should be developed, and that initial steps towards this must be taken.

Ultimately, it is clear that more progress remains to be made in the development of stained-glass conservation in the USA. Initial steps towards standardization and accreditation have begun, thanks to developments at the round-table discussion. The well-attended symposium audience was composed of conservators, architects, historic preservationists, artists, and custodians. The presence of this multitude of disciplines demonstrated an encouraging level of interest that will hopefully lead to collaboration, and continued appreciation and understanding of stained glass and the unique conservation challenges it presents.

Additional topics included the conservation challenges of dalle de verre windows (Mark Rabinowitz of Conservation Solutions, Inc., and Wes Haynes of Fish Church Conservancy); lighting design and architectural stained glass (Conor Sampson of CSDesign); the conservation of lay lights at the National Society of the Daughters of the American Revolution Library (Katie Irwin of Quinn Evan Architects and Nathan Hicks of Silman); the restoration of a medieval French stained-glass panel from the Baltimore Museum of Art (Mary Clerkin Higgins of Clerkin Higgins Stained Glass); and stained-glass conservation projects at the Library of Congress (James Zeeck of the Architect of the Capitol) and the House of Commons in Ottawa (James Maddigan of Robertson Martin Architects). The symposium concluded with site visits to the Library of Congress, the National Society of the Daughters of the American Revolution, and the National Presbyterian Church.

The symposium was sponsored by the Association for Preservation Technology International; the American Glass Guild; Washington National Cathedral; the National Center for Preservation Technology and Training; the Association for Preservation Technology, Washington DC Chapter; and the Association for Preservation Technology, New England Chapter.


Thanks are due to Catherine Williams, MA, for her assistance in the preparation of this review

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