Stained Glass - Art at the Glass Surface
Cambridge - Monday 4th and
Tuesday 5th September 2017

Jordi Bonet
<[email protected]>

article posted 17 May 2017

Jordi Bonet is Bs.Ch. Chemistry by Universitat de Barcelona and the third generation of stained glass masters at J.M.Bonet vitralls S.L. The work of Jordi Bonet is focused on the conservation of the stained glass, among his research he has worked in the conservation-restoration of cloisonné stained glass, also on the influence of Mediterranean climate in the conservation conditions of stained glass. He has made an investigation on the stained glass work of Daríus Vilàs, stained glass artist collaborator of Gaudí. He has promoted the investigation and joined the team of Prof. Pradell, and Martí Beltran to find out about the enamels used in Barcelona during the XI X century. As a stained glass conservator Jordi Bonet has worked at the XIII century windows of the Cistercian Abbey of Santes Creus, at the Cript of la Sagrada Familia of Barcelona and at the XVIII century windows of Torroella de Montgrí, to name a few. He is advisor on the conservation of the windows at Palau Güell and on the conservation of the windows of Palma de Mallorca Cathedral.

Characterization of enamel used in stained glass in Barcelona at the end of the XIX century.
T. Pradell1, M. Beltran2, J. Bonet*3

The art of stained glass in Catalonia lived especially splendorous moment in the years between the end of the XIXth century and the beginning of the XXth. Many craftsmen from all around Europe came to the city of Barcelona to settle their studio or work in some of the existing studios. Dietrich, Müller, Maumejean for instance where some that can be mentioned. Also foreign panels were sent to be installed in Catalan locations, as for example did Bazin Latteaux.

Unfortunately the stained glass produced during that time has proven to be fragile and delicate, especially the enamels and grisaille on the surface are suffering different types of deteriorations. The most common deterioration of the enamels is an opaque, white powdery aspect and can be mostly detected in blue and green paints. Most windows produced during these years show some degree of deterioration. On the other hand, older windows out of this period show very well preserved blues and greens.

The current research led by the UPC is based the old fragments, bits and stained glass paint collected by J.M.Bonet vitralls studio during the last ninety years. The sampling has been able to obtained pieces not only made by the most popular studios of the period, like Amigó or Rigalt i Granell, but also from some rare and unique windows.

Among the aim of this investigation there is the characterization of the composition of the enamel used, its interaction with the supporting glass, fluxes, and the influence of the kiln used for the firing. The stability and adherence of the enamels and grisailles depends mainly on the thermal properties (softening temperature, thermal expansion coefficient, etc) of the enamels and grisailles and of the base glass, which, in their turn, depend on their chemical composition and microstructure. The thermal properties, chemical composition and microstructure of the sample collection of enamels and grisailles is determined by Differential scanning calorimetry (DSC), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (EDX) analysis attached, Laser Ablation I nductively Coupled Plasma Mass Spectroscopy (LA-ICP-MS) and X-ray Diffraction (XRD).

The end result might give ideas in order to improve current conservation policies and urge in taking measures to protect this fragile heritage.


1. Full Professor. Departament de Física, Universitat Politecnica de Catalunya
2. Ph.D Student. Departament de Física, Universitat Politecnica de Catalunya
3. Bsch in Chemistry. Stained glass restorer at J.M.Bonet vitralls. S.L.