Alison Gilchrist reports
The team at Barley Studio has completed its four-year project to conserve the sixteenth-century stained glass of Lichfield Cathedral’s Lady Chapel, part of a larger £3.7 million restoration project [Fig. 1]. Seven of the windows were originally made for the Abbey of Herkenrode, near Liège in present-day Belgium, in the 1530s and were brought to Lichfield through the agency of Sir Brooke Boothby of Ashbourne in the first decade of the nineteenth century. In his Memoirs Illustrative of the Art of Glass-Painting (London, 1865), the nineteenth-century barrister and antiquarian Charles Winston described the Herkenrode glazing as ‘perhaps the finest specimens of pictorial glass-painting in the world’ (p. 251). Two further windows, thought to originate from Antwerp, were restored and installed to complete the Lady Chapel glazing by Charles Eamer Kempe in 1895.
Concerns about the condition of the stonework of the Lady Chapel had been raised as early as 1983, when Martin Stancliffe took over as Cathedral Architect. Surveys of the glazing highlighted loss of paintwork and corrosion of the painted surface, and in 1997, English Heritage undertook a monitoring study of the environment of the Lady Chapel windows. In 2002, Martin Stancliffe commissioned Keith Barley to survey the windows and undertake a preliminary study of their condition. Robert Kilgour took over as Cathedral Architect in 2003, and work continued with trial installations of protective glazing by Barley Studio and a sensor study of its effectiveness by the Fraunhofer Institut (Warzburg). Finally, as the long-needed repairs to the stonework became urgent, requiring the glazing to be removed for safety, the conservation work and re-installation of the windows with internally ventilated external protective glazing was agreed. Specifications and tender documents were produced in 2009, and Barley Studio began the conservation work in 2010.
During the project, we have been privileged to collaborate with stained-glass historians from the Belgian CVMA, Yvette Vanden Bemden and Isabelle Lecocq, who have regularly visited Barley Studio to study the Herkenrode windows as they were being conserved. It has been a pleasure to discuss these beautiful windows with such eminent scholars; Yvette has already published extensively on the Herkenrode glass (‘The 16th-century Stained Glass from the Former Abbey of Herkenrode in Lichfield Cathedral’, Journal of Stained Glass, XXXII (2008), 49–90) and a joint publication by the English and Belgian CVMAs is planned. As we examined each scene, we were newly astonished at the remarkable completeness of the original artwork, the result of its long history of minimal and sympathetic restoration. One element of this previous restoration was the re-use of original Herkenrode glass, carefully selected to fill areas of damage in a most unobtrusive manner. Indeed, we believe that the Herkenrode windows in Lichfield comprise more original sixteenth-century glass than survives in present-day Belgium [Fig. 2].
Barley Studio’s conservation approach has continued this tradition of minimal intervention, whilst also introducing some innovative conservation techniques with the aim of enhancing the visual appearance of the glass. As previously reported (see Vidimus 63), re-leading of the panels was not considered to be necessary, as the 1890s leadwork of Burlison & Grylls (London) and Wingfield (Birmingham) is in good condition and is reasonably sympathetic to the glass. However, many later ‘strap’ leads (probably added after the windows had been removed for safety during the Second World War) have been removed, and visually disturbing mending leads have been reduced by removing the surface leaf of the lead calme. Fractured pieces were edge bonded where necessary using conservation-grade silicone and epoxy adhesives. The glass surfaces were carefully cleaned using only deionised water on cotton wool swabs; a gentle treatment that very effectively removed the black sooty deposits covering the internal surface, considerably brightening the overall appearance [Fig. 3].
Although the glass is physically very complete, the environment has taken its toll on the imagery, as the painted detail has suffered through corrosion of the glass and paint of the internal surface. Where the paint survives, it shows the remarkable skill of the Renaissance glass-painters, with layers of delicate shading combining different colours of glass paint [Figs 4–5].
However, in some scenes the fading is so severe that faces, in particular, have been left almost completely blank, with the slightest of ghosting showing where the painted lines once were. We have undertaken some restoration of this lost painted detail in key areas of the imagery by painting on the reverse of the glass using a cold (unfired) paint mixed from traditional glass pigment and gold size [Fig. 6]. This paint is reasonably robust to water and scratching once dry, but will remain easily removable in the future, wiping off with an organic solvent such as ethanol.
Conservator Alison Gilchrist commented: ‘One of the challenges of this project was its sheer scale, both in terms of the overall windows (each around 11m tall including the tracery, totalling over 600 individual panels) and of the imagery. Each complete scene is spread over twelve or fifteen panels, so it was important to get an overview of the artwork rather than working separately on individual panels. The large light tables and viewing gallery in our new studio have come in very handy indeed! [Fig. 7]
‘Along the way we have enjoyed finding the marks left by our predecessors, who were clearly proud of their work on these windows [Fig. 8]. We have resisted the temptation to add our names to the glass, though of course all of our work is fully documented through restoration diagrams and photographs.’
Director Keith Barley added ‘Having acted as consultant to Lichfield Cathedral almost thirteen years ago, and carried out the initial trials of protective-glazing installations, I was delighted to win the contract to carry out this major conservation project. We have been able to develop innovative techniques to preserve and enhance this internationally significant glass, whilst making minimal intervention to its structure. Conserving the Herkenrode glass has been a long and rewarding project, and a very important part of my career in stained glass conservation.’
The windows have now been re-installed, protected by their new external protective glazing (which was installed when the windows were removed back in 2010). The cathedral will celebrate the return of this world-famous glazing with a service of thanksgiving and dedication on 10 March 2015.