Ageing of 'The Creation’
Multi faceted challenges in the conservation and restoration of monumental glass appliqué, as confronted in saving the appliqué stained glass post war Dutch masterpiece‘ The Creation’ by Karel Appel.
The recently started research project focuses on a neglected area of the Dutch cultural heritage; namely appliqué glass art in post war architecture. Appliqué glass can be considered a Dutch invention. Since 1951, applied arts of a monumental scale were integrated in many Dutch buildings with a public function. Glass appliqué technique involves use of blown or machine coloured glass fragments bonded to plate glass with an adhesive. Many Dutch artists of the period, amongst them the notorious Karel Appel, applied this technique for their creations. In comparison with stained glass, the appliqué technique meant a great creative freedom for the artists, without the limitations of a lead network and its specific dimensions.
But as time progressed ageing constituted a growing threat to these marvellous works of art. Many of the glass panels mentioned above are nowadays in poor condition, fall apart, adhesives are discoloured or disintegrated. Moreover, growing numbers of buildings from the post war period in the Netherlands are on the list to be demolished. Some of the windows end up in garbage containers while others are stored with a vague possibility for conservation and put back in the future.
Conservation and restoration professionals trying to save these appliqué glass windows from the grip of time are confronted with a bewildering number of challenges. It is not only about which techniques to use to clean the glass fragments, remove the decayed adhesives painstakingly and restore the glass windows to their original brilliance, but more fundamentally their work of reconstructing the original works of art consists of avoiding making the very same uninformed mistakes the original artists of the glass appliqué period made.
The adhesive quality and degradation of adhesives within the context of glass appliqué art has not received much attention up until now. There has been no adequate documentation of the materials used. Also, no serious attempts have been made to scrutinize their in-service behaviour after approximately 60 years of natural ageing. The conservators of historical glass compositions in architectural context are confronted with challenges that need more in-depth and methodical research of this multifaceted issue. Well-studied and scientifically founded sets of choices are to be made.
The case study of the wonderful applique windows 'The Creation' (1957) for the Paaskerk in Zaandam by Karel Appel offers an incredible opportunity to study glass materials, their amalgamation by means of adhesives and their ageing properties over time in all their condition’s complexity and mutual dependency. The research project discussed in this presentation focuses on isolating and describing scientifically the exact influences of the applied materials, techniques and the influence of environmental factors on the condition of the complex glass constructions under scrutiny. Insights and best practices that will be developed in this project are meant to be tools and theoretical frameworks for both glass conservators and scientists in the area of cultural heritage.
Keywords: Architectural glass, post war appliqué glass, glass-to-glass bonding, ageing, conservation and restoration strategy.