article posted 13 Jun 2016
Jonathan Cooke ACR served a traditional four-year apprenticeship at York Minster: he has worked as an
independent stained glass conservator since 1987. He undertakes stained glass conservation projects
throughout the UK and beyond: most are ecclesiastical, and he also works for a number of national and
regional museums, the National Trust and private clients. He teaches glass-painting regularly at
Swansea and elsewhere - this year in Trondheim and York. His glass-painting manual
Time and Temperature
was published by Swansea Metropolitan University in 2012.
Glass jigsaw puzzles; a conservator's notebook
Jonathan & Ruth Cooke Ltd, Stained Glass Conservation, 5 Tivoli Place, Ilkley, LS29 8SU
phone: 01943 602521 mobile: 07968 967490
Architectural glass is vulnerable to loss through neglect, accidental or intentional damage, and deterioration
over time, and with each successive restoration and rearrangement of what remains.
Attitudes to the stained glass of previous generations have varied at different periods: the concept of the
'conservation glazier' is arguably something of a late c20 phenomenon. Previous restorations and reorderings
present complex challenges: while there are more advanced conservation techniques and materials now
available, the ethical debate about the purpose as well as the scope of any restoration continues, and this
is particularly sensitive in the case of degraded or jumbled ecclesiastical glazing. In the nineteenth century
and sometimes later, restoration of ancient glass could include a generous amount of artistic licence.
In the recent past, conservation has sometimes resulted in a fossilisation of an intermediate arrangement
at an arbitrary point in its existence; there are also instances of careful collaborations to achieve
improvements in legibility. Sometimes the glass is deemed to be beyond practical conservation by any
Using a series of varied examples, this presentation provides an overview of dilemmas encountered by
the conservator, client and heritage bodies, and an insight into decision making processes and
contrasting results of various 'conservation' interventions.