Medieval Stained Glass Windows Research Articles

Impact of a Mn-oxidizing bacterial strain on the dissolution and browning of a Mn-bearing potash-lime silicate glass

This work aims to investigate the role played by a model Mn-oxidizing bacterial strain and its exudates on the alteration of Mn-bearing potash-lime silicate glasses representative of medieval stained glass windows. Two model glasses, with or without manganese, were prepared and used for abiotic and Pseudomonas putida inoculated dissolution experiments. Results show that the presence of P. putida slows down the dissolution kinetics while changing the dissolution stoichiometry. In biotic experiments, the acidification of the solution at the beginning of the experiment favors the release of K. After a few days, a drop in Mn and P in solution is observed, retained by bacterial cells. Reciprocally, the amount of glass influences bacterial behavior. The more glass, the faster the bacterial population increases in size and produces siderophore. In the presence of the Mn-bearing glass, siderophore production is followed by the formation of brown phases, identified as Mn oxides.

Catholic Church Interiors in Fin-de-Siècle Literature

The works of such late-Victorian writers as Lionel Johnson, Ernest Dowson, Theodore Wratislaw, John Oliver Hobbes and Oscar Wilde represent Catholic churches as retreats set apart from the ugliness and mediocrity of Victorian England—religious versions of Des Esseintes’s Fontenay-aux-Roses house in À rebours—filled with incense, organ music, and coloured light filtering through medieval stained-glass windows. In Dowson’s correspondence or in his poem ‘Benedictio Domini’, in Johnson’s ‘Our Lady of France’, in Wratislaw’s ‘Palm Sunday’ and ‘Songs to Elizabeth’, in some of Wilde’s stories, the opposition between inside and outside expresses figuratively the fundamental incompatibility between an ideal of beauty, embodied in the aesthetic experience of the church, and the coarseness of the outside world. This article explores how such a polarised vision reflects contemporary debates about the interior organisation and decoration of churches. Drawing on William Whyte’s analyses of changing attitudes towards church architecture in the 19th century in Unlocking the Church: The Lost Secrets of Victorian Sacred Space (OUP 2017), it shows how literary representations of church interiors in fin-de-siècle literature reflect the shift from the Protestant aniconic, congregation-centred approach to church design, in favour of an architecture of affect and sensation, where space and ornamentation lead the worshipper to experience the divine through a sensory overload. It focuses on two aspects of church architecture and decoration that are foregrounded in fin-de-siècle poetry and fiction—and were highly polemical in the late Victorian context because of their association with the Ritualist controversy and with ‘Romishness’: the eastward position, i.e. the celebration of the Eucharist on a stone altar fixed to the back of the chancel rather than on a wooden communion table facing the congregation; and altar candles, which were condemned in anti-ritualist pamphlets as both pagan and ‘popish’. Through these two examples, this article argues that fin-de-siècle literary representations of church interiors reflect a major change in the perception of sacred space, from the ‘auditory church’ (Whyte) of the 18th century, where function (essentially focused on the proclamation of the word of God) dictated the organisation of space and even the furnishings, to the ‘visual church’, saturated with symbolism, where the eye, rather than the ear, becomes the central organ of religious experience.

Adapting the study of the stained‐glass windows of Notre‐Dame de Paris cathedral to the challenge of restoring a damaged listed building

The first comprehensive study of the cathedral's medieval stained-glass windows, supported by restoration charts, was carried out in 1959 by the art historian Jean Lafond and was the first of the collection of French works in the Corpus Vitrearum. Since that date, the publication of the inventory of ancient stained-glass windows in France, as well as other publications, have widened our knowledge of the stainedglass windows of Notre-Dame. The three medieval roses are the most important elements of Notre-Dame's glass heritage. Dating back to the 13 th century, they show evidence of the restorations carried out across the centuries. In the west rose which depicts a psychomachia, the zodiac and the Labours of the Months, only eleven of the original panels are still in place. In the north transept, the rose depicting the Virgin Mary surrounded by figures of the Old Testament is the best preserved window. The rose located in the south, which originally depicted a majestic God presiding over an assembly of saints, virgins and angels, has been substantially modified. A large number of stopgaps are observed in these three roses and are a sign of the restoration techniques used during the 18 th century. The coats of arms of Cardinal and Marshal Noailles, found in one of the choir chapels, are the two last vestiges of this period. The 18 th -century decoration was, in turn, replaced during the restoration of the cathedral by Lassus and Viollet-le-Duc. In keeping with medieval traditions, they sought to present stained-glass windows with large figures in the upper windows of the choir, narrative stained-glass windows in some chapels and grisaille stained-glass windows for the rest of the building. This project took more than ten years to accomplish and was carried out by seven glass painting workshops, chosen amongst the best of their time and assisted by a painter. To restore the missing stained-glass windows, the architects relied on the small number of written reports describing the stained-glass windows before their destruction, but also on the details of fragments remaining in the cathedral, and the stained-glass windows of other medieval buildings. In the second half of the 20 th century, the grisaille windows that had been installed in the nave in the previous century were in turn replaced with abstract windows created by Jacques Le Chevallier. Since 2019, art historians from the Glass working group have been actively committed to updating and synthesizing the historical data on all of the cathedral's stained-glass windows. Documentary research will help to guide the observation of the works and will be completed, in the case of the original stained-glass windows, with the revision of the 1959 restoration chart. The study of the 19 th -century stained-glass windows will focus on the search for archaeological models, on the quality of the materials (glass, lead, etc.) and their implementation, but also on the specificity of the painting work, and ultimately providing a better knowledge of the workshops of glass painters who worked for Notre-Dame.

Glass colourations caused by Mn-Fe redox pair : Application to ancient glass technology

Manganese is a chemical element used as a colourizer in glass industry since antiquity. Combined with iron, manganese often plays the role of a decolourizer leading to uncoloured glasses used to represent hands and faces in medieval stained glass windows. A series of medieval-like glasses has been synthesized in order to relate the colouration of glasses with the conditions of synthesis (temperature, atmosphere, glass composition). Optical absorption spectra in the UV–Vis-NIR range have been measured to follow and characterize the changes in colouration. For a given temperature, the addition of Mn in a Fe-rich glass composition implies a decrease of the concentration in Fe2+and an increase of the concentration in Fe3+ as compared to the Mn-free glass composition. The uncoloured glass composition is obtained for different contents of Mn when melting temperature varies. These results might help deciphering the complexity of colour making in ancient times.

Hydrochromic Smart Windows to Remove Harmful Substances by Mimicking Medieval European Stained Glasses.

Medieval European stained glass windows are known to display various splendid colors and remove harmful airborne substances. At present, the functions of medieval stained glass windows are imperative, from the environment, health, and energy perspectives, to develop multi-functional windows that report/control environmental conditions and remove harmful substances by utilizing visible-near-infrared light sources. Here, we suggest a strategy to mimic medieval European stained glasses for devising plasmonic-based multi-functional smart stained glass windows. The stained glass windows are prepared from the deposition of gold nanoparticles on a glass that is preliminarily coated with a responsive colloidal nanosheet. The temperature responsiveness of the nanosheet enables the effective control the gold nanoparticle density of the stained glasses. Therefore, the windows can display blue, violet, and cranberry colors. The colors become iridescent by introducing a photonic crystal monolayer. The stained glass windows are hydrochromic: they switch the colors (blue ↔ cranberry) and modulate light transmittance depending on humidity conditions. Moreover, they can remove formaldehyde under the illumination of a low-power indoor light. These functions provide a new platform for the futuristic smart windows that clean indoor air for the human health and save energy.

Analytical investigation of 14th century stained glass windows from Santa Croce Basilica in Florence

AbstractThe Basilica di Santa Croce (Basilica of the Holy Cross) is the major Franciscan church in Florence (Italy). Among the prominent masterpieces preserved in this church, there are 22 medieval stained glass windows. Between 2000 and 2013, the Opera di Santa Croce started a restoration campaign of six of the most important ones, dated 14th c. In this paper, the archaeometric data collected during the restoration campaign are reported. Two major base glass compositions (potash‐lime‐silica and soda‐lime‐silica) were identified by quantitative chemical analysis. Results are compared with similar investigations on Italian stained glass windows of the 14th‐15th centuries and many similarities are highlighted. Some interesting “secrets” of the coloring techniques based also on multilayer glass pieces were revealed. Finally, SEM‐EDS analyses allowed the main weathering glass phenomena to be investigated.

Long-term weathering rate of stained-glass windows using H and O isotopes

The understanding of glass alteration is a biogeochemical, industrial, societal (radioactive waste confinement), and cultural heritage issue. Studies have been mainly performed in aqueous conditions. However, glass reactivity under hydraulically unsaturated conditions may be more important than previously recognized. In this context, we evaluate here the role of the alteration layer formed on medieval stained-glass windows on the ongoing alteration in unsaturated conditions. H2O adsorption isotherms were measured to study the relation between the vapor sorption and the relative humidity inside the alteration layer. From it, the average pore radius was calculated, yielding a water vapor diffusion coefficient of 7.8 × 10-7 m² s-1 inside the pore network. Experiments using doped water vapor (D218O) confirm the vapor transport up to the alteration front via fractures and pore network. They also demonstrate that the alteration mainly progresses via an interdiffusion mechanism. The calculated interdiffusion coefficients at 20 °C are 3.6 × 10-20 m2 s-1 at 70% RH and 4.9 × 10-20 m2 s-1 at 90% RH, which is similar to the values measured on model stained-glass samples altered in short durations (1–4 years). Therefore, this study highlights that, given its morphology, the alteration layer is not protective against vapor transport and interdiffusion.

Chemical composition and alteration processes of glasses from the Cathedral of León (Spain)

The Cathedral of León has one of the most important ensembles of medieval stained glass windows in Europe; however, most of them have been altered by atmospheric weathering. The main objective of this study was the characterization of a set of glass samples from the Cathedral of León, the comparison with glasses from previous interventions in the cathedral and the study of the relation between the alteration pathologies, the chemical composition of the glasses and the environment in which they were placed. The samples were characterized by means of binocular microscopy, scanning electron microscopy and energy dispersive X-ray spectrometry, visible spectrophotometry, X-ray fluorescence spectrometry and X-ray diffraction. The main alteration of glasses exposed until the 19th century was the formation of pits by dealkalinization, while the glasses exposed until the present formed CaSO4 deposits as a consequence of the synergic effect of rainwater and gaseous pollutants. Glasses altered by the browning of manganese were also characterized.

Urban air pollutants and their micro effects on medieval stained glass windows

Levels of urban gaseous and particulate pollutants were investigated in the Cathedral of Cologne, Germany in the framework of the EU-project “VIDRIO”. The purpose of this study was to evaluate the influence of a protective double glazing system on the preservation of ancient stained glass windows by sampling at protected and unprotected windows (indoors, in the interspace and outdoor of the Cathedral). The interspace between the ancient stained glass window and the protective glazing is flushed in the Cathedral by indoor air, hence isolating the historic glass from the outdoor air and exposing it to indoor air on both sides of the glass panels. Concentrations of aggressive gaseous pollutants such as NO2, SO2, O3 and CO2 as well as elemental concentrations of bulk particles and relative abundances of single particles were surveyed at all sampling locations. Elemental concentrations in bulk particulate matter were found to be significantly lower inside the Cathedral in comparison to the outdoor air. This result is advantageous for the stained glass windows. Single particle analysis of the samples from Cologne showed also soil dust and organic particles as well as sulphates and nitrates, from which the latter two compounds are dangerous for the stained glass windows. On the base of the obtained results, it can be concluded that the protective glazing system in the Cathedral of Cologne can be considered as predominantly advantageous from both the gases' point of view (except for NO2-candles burning) and from the particles' point of view.

Red layered medieval stained glass window characterization by means of micro-PIXE technique

Red layered medieval stained glass windows on a transparent greenish substrate are characteristic of European medieval cathedrals, but few compositional analyses have been performed on the coloured layers. The PIXE technique has been performed on a red layered stained glass window obtained during the restoration works carried out in Las Huelgas Monastery in Burgos (Spain). Protons of 3MeV with a beam of 4×5μm2 were used to acquire elemental maps of a cross section of the sample, in order to observe the homogeneity of the layered structure and its substrate.In our work, copper was detected as in other layered glasses but a correspondence with lower amounts of zinc has also been determined. Both elements appear enriched in the red coloured layers, while the other quantified elements have the same relative composition along the sample. Corrosion layers, due to the lead supporting structure of the window, were also found.

Long term assessment of atmospheric decay of stained glass windows

Several studies indicate that the decay of medieval stained glass windows is related to both the glass composition and the characteristics of the environment. The kinetics of the decay processes has been always described through experiences performed in aqueous confined conditions, which are obviously not encountered in real condition. A research programme has been set up in order to assess the kinetics of atmospheric weathering. The long and short term weathering has been studied through respectively ancient glass fragments and glass analogues exposed in the field. This paper presents the preliminary results of the long term. A characterisation of the morphology and chemical modification induced by weathering has been performed. Results will be used in the next step to build up a model of long term atmospheric weathering kinetics.

Early stage of weathering of medieval-like potash–lime model glass: evaluation of key factors

Throughout history, a consequent part of the medieval stained glass windows have been lost, mostly because of deliberate or accidental mechanic destruction during war or revolution, but, in some cases, did not withstand the test of time simply because of their low durability. Indeed, the glasses that remain nowadays are for many in a poor state of conservation and are heavily deteriorated. Under general exposure conditions, stained glass windows undergo different kinds of weathering processes that modify their optical properties, chemistry, and structure: congruent dissolution, leaching, and particle deposition (the combination of those two leading together to the formation of neocrystallisations and eventually crusts). Previous research has studied the weathering forms and the mechanisms from which they are originated, some others identified the main environmental parameters responsible for the deterioration and highlighted that both intrinsic (glass composition) and extrinsic (environmental parameters) factors influence glass degradation. Nevertheless, a clear quantification of the impact of the different deterioration extrinsic factors has not been performed. By analysing the results obtained with model glass (durable and nondurable) exposed in the field, this paper proposes a simple mathematical computation evaluating the contribution of the different weathering factors for the early stages of exposure of the stained glasses. In the case of non durable glass, water runoff was identified as the main factor inducing the leaching (83.4 ± 2.6% contribution), followed by gas (6.4 ± 1.5%) and particle deposition (6.8 ± 2.2%) and adsorbed water (3.4 ± 0.6%). Moreover, it was shown that the extrinsic stimuli superimposes with the impact of glass composition to the weathering. Those results show that the role played by dry deposition, even if less important than that of the wet deposition, cannot be neglected.

Corrosion of Lead Glasses by SO<sub>2</sub> Gas

This paper presents the corrosion of potassic glasses by SO2 gas at high-temperature. The corrosion phenomenon of potassic glass is well-known for medieval stained-glass windows under natural conditions of weathering [1]. Nevertheless the corrosion is also possible without humidity at high temperature in presence of polluting gas such as SO2 gas in the furnace. All source of SO2 gas can thermodynamically involve the main formation of K2SO4 and other alkaline salts such as Na2SO4. This corrosion manifests itself by the presence of “white flakes” in the bulk glass and this defect leads to discard of the piece for a crystal-maker like Daum. Alkali sulphate formation was determined by using scanning electron microscopy and presents a very particular morphology. This study allowed underlining on, one hand the influence of the temperature and on the other hand the role of gas concentration on the formation of the potassium sulphate. Thermal analysis technique (TGA) was carried out in order to understand the corrosion chemical kinetic of potassic glasses by SO2 gas.

Investigation of gaseous and particulate air pollutants at the Basilica Saint-Urbain in Troyes, related to the preservation of the medieval stained glass windows

The influence of a protective double glazing system in the preservation of ancient stained glass windows in the Basilica Saint-Urbain, Troyes (France) was evaluated. In order to study the levels of gaseous and particulate pollutants, sampling was performed at protected and unprotected windows, as well as indoor, in the interspace and outdoor of the Basilica. Measurements were carried out for a period of one year. The concentration of NO2 was found to be higher inside of the church than in the interspace and outside of the church in contrast to O3 and SO2, which showed higher concentrations outdoor. In the case of CO2, an average concentration of 412 µg g−1 inside the Basilica was detected. However, during special ceremonies quite high, but only short-term lasting CO2-levels were observed. For the bulk analysis and for the studies of the chemical composition and abundance of individual particles, energy dispersive X-ray fluorescence (EDXRF) and electron probe micro analysis (EPMA) were applied. The average concentrations in bulk particles of the elements Al, Si, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, and Pb were comparably high indoors and outdoors. The composition of single particles was found to be more aggressive inside the church than outside. The fine fraction consisted mostly of soil dust, organic particles, ammonium nitrate and Ca–O–C-rich particles. In the coarse fraction, Ca–O–C-rich and organic particles showed the highest abundances. In the interspace also ammonium sulfate was detected. The results show that the installation of the protective glazing in the Basilica Saint-Urbain is from the gases’ point of view predominantly advantageous, but from the particles’ point of view it is only fairly good.

Thermal Stress as a Possible Cause of Paintwork Loss in Medieval Stained Glass Windows

One of the main causes of the loss of paintwork from medieval stained glass windows is the propagation of cracks in the grisaille and in the underlying glass, which cannot be considered the result of a stabilization process, but the evidence of an ongoing stress. The thermal behaviour of different-coloured painted glass pieces exposed to direct solar radiation was investigated in order to study the effect of thermal stresses on the conservation of the paintwork. Experimental results have been compared with laboratory tests as well as with measurements carried out on original stained glass windows. The grisaille showed a thermal behaviour similar to that of the glass on which it is fired. A clear correlation was found between the glass thermal cycles, the increase in stress at the glass–grisaille interface and the growth of cracks in the grisaille. According to these results, protective glazing aids the preservation of the paintwork from the risk of damage and loss, reducing the thermal stresses on the glass of the stained glass windows in terms of amplitude and frequency.

Medieval stained glass windows from Pavia Carthusian monastery (northern Italy)

Abstract Stained glass windows of the Carthusian monastery (Certosa) of Pavia (15th century) were investigated during a recent restoration campaign, to define chemical compositions and to understand manufacture techniques. Analyses were performed on six stained glass windows, representing S. Caterina (St. Catherine), S. Gregorio (St. Gregory), S. Agostino (St. Augustine), la Natività (the Nativity), S. Bernardo (St. Bernard) and S. Girolamo (St. Jerome), and on two undecorated windows. The methodological approach couples micro-sampling with micro-analyses. The detailed chemical analysis reveals four compositionally distinct glass-types: mixed alkali, soda and two potash glass types. These last two types display a rather constant MgO content but variable CaO content and define two main compositional clusters, CaO rich (Type II) and CaO poor (Type III), that have been ascribed to the pristine glass. The compositional boundary of Type II and Type III glass fits those already defined in recent literature. The mixed alkali and soda glass are considered to be related to later repairs. The narrow compositional cluster represents a good statistical result defining the composition of the pristine glass panes and allows compositional comparisons with stained glass from coeval cathedrals of Northern Europe (Germany, Switzerland and France). Close similarities are found to stained glass from Rouen and St. Maur des Fosses.

A conservation assessment on metallic elements from Spanish Medieval stained glass windows

This paper is focused on the analysis of some metallic materials (lead cames and iron supporting elements) from Spanish Medieval stained glass windows of the Monastery of Pedralbes (Barcelona) and the Cathedral of Seville. The main goal of the research was to assess their current state of conservation by studying processes of decay and corrosion due to weathering. The samples were characterised through metallographic examinations, conventional wet chemical analysis, scanning electron microscopy (SEM), energy dispersive X-ray microanalyses (EDX), and X-ray diffraction (XRD). The degree of deterioration has proved to be stronger in iron elements than in lead ones, providing data that are useful for future restoration and conservation of such historical materials and for approaching technological aspects of ancient production processes.

Alteration processes of medieval stained glass windows. Study and protection treatments

The anxiety caused by the fast growing decay of historical stained glass windows as a consequence of increasing environmental pollution, encouraged institutions of several countries to sponsor a series of scientific works aimed both to slow down this fast forwarding deterioration and to develop repair and preservation methods. After an initial review of the chemical composition of the stained glass windows and of the differences depending on historical epochs and origins, a discussion about chemical attack mechanisms, degradation processes and formation of superficial crusts opens up. Finally, the methodology used in their cleaning and restoration is briefly exposed and some criteria on the still polemic quest.