A Transparent Dialogue Between Iconography and Chemical Characterisation: A Set of Foreign Stained Glasses in Portugal Alexandra J. Rodrigues ( [email protected] ) Instituto Politecnico de Setubal Escola Superior de Tecnologia do Barreiro https://orcid.org/0000-0002- 4688-7159 Mathilda Larsson Coutinho Laboratório HERCULES, Universidade de Évora Andreia Machado VICARTE Research Unit Bruno A. Martinho Parques de Sintra - Monte da Lua Luís Cerqueira Alves C2TN: Centro de Ciencias e Tecnologias Nucleares Maria Filomena Macedo Faculty of Science and Technology: Universidade Nova de Lisboa Faculdade de Ciencias e Tecnologia Márcia Vilarigues Universidade Nova de Lisboa Faculdade de Ciências e Tecnologia: Universidade Nova de Lisboa Faculdade de Ciencias e Tecnologia Research article Keywords: stained glass, iconography, chemical composition, u-EDXRF, UV-Vis spectroscopy, PCA Posted Date: October 29th, 2020 DOI: https://doi.org/10.21203/rs.3.rs-97368/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Version of Record: A version of this preprint was published on February 18th, 2021. See the published version at https://doi.org/10.1186/s40494-021-00480-w. Rodrigues et al. RESEARCH A transparent dialogue between iconography and chemical characterisation: a set of foreign stained glasses in Portugal Alexandra Rodrigues1*†, Mathilda Coutinho1,2, Andreia Machado1, Bruno A. Martinho3, Lu´ıs Cerqueira4, Maria Filomena Macedo1,5 and M´arcia Vilarigues1,5 Abstract This work presents the first results of the iconographic study and analytical characterisation of a set of four stained-glass panels that are part of the collection of National Palace of Pena (Sintra, Portugal). These panels were collected by the King Ferdinand II in the mid-19th century, for his main residence the Palace of Necessidades (Lisbon, Portugal), and only first presented to the general public in 2011. This study contributes with the knowledge of Technichal Art History and Heritage Science to a better and deeper understanding of their history, materials and techniques used in the production, where an art-historical and a scientific approach are applied to attribute their origins. Based on the analysis of the formal and stylistic characteristic of the panels, it is proposed that the drawings used for the production of three of these panels may be based on the design and painting being carried out in the same workshop, and that the four panels have the same provenance (Germany). The composition of the glass and grisaille was determined and colourising elements were identified. Through this approach, conclusive correlation among the analysed glasses was possible: all are calcium rich or calcium-potassium rich types, and the results also suggest that the same source of silica was used for their production. A typical mixture of glass and lead oxide was found on the grisaille applied on the painted panels. However, less usual was the use of a copper oxide pigment for the black grisaille. All these findings support the proposals made regarding provenance and production period (15th century). Keywords: stained glass; iconography; chemical composition; µ-EDXRF; UV-Vis spectroscopy; PCA Introduction mestic setting with highly personalised imagery. From The art of stained glass has always sought to interact the 18th century onwards, medieval and later stained- with the surrounding space by creating architectural glass panels were collected in order to decorate pri- planes that allowed illumination while transforming vate houses and chapels [1–3], often bought in the art the experience of light into one specific and meaning- market and/or through an intricate network of deal- ful to the purpose of a building [1]. From the begin- ers which grew throughout the 19th century [4]. This ning, production of stained glass developed side by side was the case of Ferdinand II’s stained-glass collection, with economic, social and cultural innovations. In the housed today at the Pena National Palace (PNP) [5]. Middle Ages, stained glass gained an important role These stained-glass panels – produced in central Eu- with the construction of cathedrals, reaching its peak rope (namely, in the territories of modern Switzerland, in the 15th century with Gothic architecture. During Germany and the Netherlands) – had been originally the Renaissance period, single glass sheet panels and installed in churches, monasteries, manor houses, and roundels showing themes of family and local interest artisan’s workshops, prior to their disposal in the Por- brought stained glass into a more intimate and do- tuguese Palaces, which is merely a short chapter in their long history [5]. *Correspondence: [email protected], [email protected] 1VICARTE, Research Unit Vidro e Cerˆamica para as Artes, Hangar III, The history of this unique stained-glass collection FCT-NOVA, campus da Caparica, 2829-516 Caparica, Portugal begins with King Ferdinand II (1816-1885) – born and Full list of author information is available at the end of the article raised in Vienna, married to Queen Maria II (1819- †Current research position at Escola Superior de Tecnologia do Barreiro, Instituto Polit´ecnico de Set´ubal, Portugal. Research for this article fully 1843) since 1836, and King of Portugal since 1837 [6] developed as member of VICARTE Research Unit. –, who dedicated part of his life to collect and finance Rodrigues et al. Page 2 of 14 works of art and his vast collection of glassware and Fluorescence (µ-EDXRF) was used in order to obtain stained glass occupied a place of pride [5]. a non-destructive characterisation of the composition Ferdinand II kept the greater part of the objects ac- the glass and grisaille used in the production of three of quired in Portugal and overseas – collections of paint- the panels (Virgin of the Apocalypse, Saint Ambrose, ings, armour, sculptures, porcelain and others – in his Saint Gregory). This information was, in turn, used royal residence, the Palace of Necessidades (located in to help establish the origins, art schools and artistic Lisbon). These collecting activities included a group trends involved in the manufacture of the panels, as stained-glass panels of different origins and sizes, with well as its recently established relation with the fourth which he decorated the windows of the Palace’s din- element (Sigmund von Sch¨onfels’ coat of arms). ing room, very much in the style of the other Saxe- Coburgs’ castles [5, 6]. Later in his life, he lived in Materials and Methods the old cloister of Pena (restored and turned into a Visual observation and art-historical approach Palace), where he also ordered to be mounted another The four panels under study are nowadays held by group of stained-glass panels in the windows of the PNP (acc. nrs. PNP2809, PNP2810, PNP2821 and Great Hall [6]. The choice for the use of stained-glass PNP2822) (figs. 1 to 2). These stained glasses were windows in the openings of the main rooms of resi- observed with the aim of understanding their produc- dences reflected a central and northern European tra- tion technology and evaluating their state of conserva- dition [6]. tion. An iconographic analysis (an art historical anal- Unlike the windows installed in the main hall of ysis) also made use of observation, and of what could Pena Palace’s, the stained-glass windows first located be seen in the objects being considered. On the ba- in Palace of Necessidades remained unknown to the sis of these observations, the objects were related to general public until very recently. As such, the trans- other primary sources (images and texts), and since ference of the panels to PNP is a story in and of it- this work is published elsewhere [10], it will herein be self [6]. The stained-glass windows were transferred used as single reference, providing it is an authoritative by 1949, since during the Republic (after 1910), the secondary source. Palace of Necessidades was handed over to the Min- istry of Foreign Affairs and its contents were stored Chemical analyses and statistical methods and gradually dispersed. It was in 1949 that, after be- Energy Dispersive X-ray Fluorescence ing requested by the conservator of PNP, the ‘eight Concerning the chemical characterisation, several frag- wooden frames with stained-glass windows’ arrived at ments of the panels of Virgin of the Apocalypse, Saint this Palace. Unfortunately, their poor state of preser- Ambrose, Saint Gregory (fig. 1) were accessible to vation required an intervention before they could be be analysed by µ-EDXRF. The analyses were carried installed, and so they were to lie forgotten in the store- out using an ArtTAX, Intax R spectrometer, equipped room for the next sixty years [6]. It was only in 2010- with an air-cooled low-power X-ray tube with a Mo 2011 that this important and unique group of stained target and Xflash R Peltier cooled silicon drift detec- glass panels was restored and displayed [6]. The col- tor. The primary X-ray beam is focused to a diameter lection’s main group currently consists of thirty-seven of 70 micrometers by means of a polycapillary X-ray panels, to which ninety Fernsterbierscheiben (window mini lens. The spectrometer was operated at 40 kV, 0.6 beer panels, i.e. small rectangular glass pieces painted mA and 360 s acquisition time, in a He atmosphere. At to celebrate the opening of a house or an important least three different measurements were made in each family event, such as a wedding) have been added. This glass fragment selected, based on their visual aspect is a highly diverse set of stained-glass panels, produced (colour, etc.). between the 14th and 18th centuries, which were ran- Quantitative analyses were carried out with the domly grouped together [7]. WinAXIL program, making use of spectra obtained This study aims to contribute to the knowledge of from CMOG A, B, C and D glass standards.