Glass Reflections
Cambridge 7th to 9th September

Presenting Author:
Tom Küpper

article posted 20 Mar 2015

H Tom Küpper

Tom Küpper was raised and educated in Bad Neuenahr-Ahrweiler, Germany. In the early 1980's he moved to the UK, setting up a small stained-glass studio in Cockermouth, Cumbria. In 1993 he joined the Lincoln Cathedral Glazing Department and has been Team Leader of the department since 1999.

Tom gained his Postgraduate Diploma in the "Conservation of Historic Objects" from DeMontfort University, Lincoln in 2001 and his MA in 2003 in the same subject. His dissertation topic discussed "Manganese Browning on Medieval Glass". Since 2011 he has been an Accredited Conservator Restorer (ACR) awarded by the Institute of Conservation (ICON). Tom is a stained glass conservation advisor to both the Lincoln and the Nottingham Diocesan Advisory Committee and to the Church Building Council, London. In the past he has lectured at the University of York, and at Savannah Technical College, Georgia, USA. Tom has written and published a number of papers on the subject of historic stained glass and its conservation and has given presentations on the same subjects. Tom is currently studying for a PhD at Lincoln University researching "19th Century Amateur Art in Places of Christian Worship".

Contact details:

Mr. Tom Küpper
Lincoln Cathedral
Works Department
28 Eastgate
Lincoln LN2 4AA
Great Britain

'Preparing a Poultice'
Stained Glass Conservation

H. Tom Küpper
Lincoln Cathedral

In December 2008 an intruder badly damaged a section of a thirteenth century stained glass window whilst escaping from inside the Cathedral. The broken window, one of the oldest in the Cathedral, is one of a set of four lancets containing images of Old and New Testament stories. When the damaged occurred it was first suggested to restore the panel and place it back into the building. However, after examining the artefact and the conservation necessary it became apparent that this may be an opportunity to conserve all of the medieval glass within the four windows together with the medieval wrought iron lug bar ferramenta and the historic oak timber sub-frames.

Nothing ever happens quickly in a cathedral, well at least not in Lincoln and seven years on, after a series of meetings, discussions, research & development, policy making and finding the necessary funds Lincoln Cathedral Glazing Department is about to begin on the conservation of the four lancet windows which is scheduled to take between 4-6 years.

The paper will discuss some of the key elements of the forthcoming conservation.
... The mapping of the windows using state of the art digital documentation especially developed for the project.
... How to deal with the extremely corroded external glass surfaces and to what extent the pollution and deterioration crusts can be removed. Is chemical cleaning appropriate compared to mechanical cleaning techniques, and what type of chemicals and methods are suitable? Will the gel layer be damaged?
... How to approach the conservation of the internal side of the glass with its entirely different deterioration catalogue of fine surface dirt adhering onto friable glass paint. What are the appropriate cleaning and stabilisation methods here?
... What about the art historical aspect and the significance of the artefact. Should the glass be re-ordered for a better interpretation and is a subsequent re-leading justified?
... What happens after conservation? Are the windows going to be protectively glazed? Is environmental monitoring necessary to record the surrounding climatic conditions and what about the visual impact of a protective glazing?
... Do we need assistance from other conservators, IT experts, material scientists or environmental specialist to deal with the particular issues which are out of the knowledge base and the expertise of a stained glass conservator?
... Not to forget to mention the medieval ferramenta and the timber frames. How are these components going to fit neatly into the conservation scheme?
... Whilst all this work is going on how can we assure minimum disruption to the building and still guarantee a visitor experience for the many visiting tourists and worshippers?

Questions upon questions.

There are indeed a number of key points which are not only raising practical and technical issues but also philosophical and ethical debates which need to be addressed before any complex conservation of historic stained glass can take place.

The talk is an attempt to address at least some of the issues guiding the audience in a practical approach through the various project stages.

Figure Captions:

Fig. 1: Four medieval lancets under the Bishop's Eye rose window. Image: Dean & Chapter, Lincoln.
Fig. 2: Damaged medieval panel. Image: Dean & Chapter, Lincoln.
Fig. 3: Pre-conservation cleaning. Sample 1. Image: Dean & Chapter, Lincoln.
Fig. 4: ESEM picture. Sample 1 before cleaning. Image: Federal Institute for Materials Research and Testing (BAM).
Fig. 5: Monitoring of various surface temperatures. Image: Tobit Curteis Associates.