Next Article in Journal
Multidisciplinary Approach to the Study of Tableware and Common Wares from Early Medieval Tokharistan
Previous Article in Journal
Radiocarbon Ages of a Possible Titian Painting
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Heritage
Volume 8
Issue 2
10.3390/heritage8020064
heritage-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Diagnostics and Analytical Campaign as Support for the Restoration Activity of a 14th-Century Mural Painting Representing the Virgo Lactans

by
Valery Tovazzi
1,
Claudia Pelosi
2,*,
Claudio Falcucci
3,
Mark Gittins
1 and
Luca Lanteri
2
1
Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), University of Tuscia, Largo dell’Università, 01100 Viterbo, Italy
2
Department of Economics, Engineering, Society and Business Organization (DEIM), University of Tuscia, Largo dell’Università, 01100 Viterbo, Italy
3
Methodology of Investigation for Artistic Diagnostics (M.I.D.A.), Via Leccosa, 15/16, 00186 Rome, Italy
*
Author to whom correspondence should be addressed.
Heritage 2025, 8(2), 64; https://doi.org/10.3390/heritage8020064
Submission received: 16 January 2025 / Revised: 4 February 2025 / Accepted: 5 February 2025 / Published: 7 February 2025
(This article belongs to the Section Materials and Heritage)
Browse Figures
Review Reports Versions Notes

Abstract

:
The restoration of medieval wall paintings often involves the combination of heterogeneous techniques and materials considering their nature and period. One of the many obstacles in the study of the restoration of these types of artifacts is the paucity of sources that remain and the fragmentary nature of the paintings. As support, we can identify information about the modus operandi of the artists and artisans’ workshops that were active in the medieval period. Such information can be derived from important treatises-for example, Theophilus’ mid-12th-century treatise, the Diversarum artium Schedula, and chapter XV of Cennino Cennini’s Book of Art. These all coincide with the paintings presented in this paper, which represent the Virgo Lactans (or Madonna del Latte, Nursing Virgin) and a likely pre-existing figure of a praying woman. The investigated wall paintings are located in the porch of St. Andrew’s church, situated in the neighborhood of Pianoscarano (Viterbo, Central Italy). The historical context and the execution technique of the paintings were carefully studied, supported by a diagnostic and analytical campaign carried out by means of hypercolorimetric multispectral imaging, spot X-ray fluorescence spectroscopy using a portable instrument, Fourier transform infrared spectroscopy, and cross-section analysis. These analyses allowed us to characterize the original materials, the stratigraphic sequence of the paintings, and the previous interventions applied to the paintings’ layers, giving relevant data to support the recently concluded restoration.

1. Introduction

The object of the present work is the diagnostic study of a very fragmentary wall painting dating back to the 14th century and representing the Virgo Lactans (Nursing Virgin, or the Virgin Breastfeeding the Christ Child) and a praying woman, as deduced from iconographic evidence [1] (pp. 65–68). The wall painting is located in the porch of St. Andrew’s church in Viterbo (Central Italy), specifically in the ancient quarter of Pianoscarano (Figure 1).
The motivation for this study was supplied by the recent restoration activity performed during a Master’s degree thesis on the conservation and restoration of cultural heritage [1]. At the beginning of the restoration, the wall painting was characterized by the presence of several layers of previous intervention, both ancient and modern ones, which made the reading and interpretation of the original iconography challenging [2]. This situation is typical in the context of medieval wall paintings, and the restoration of such artwork requires careful archival research and scientific analysis to aid the choices made during the intervention [3,4,5,6,7]. In fact, the current restoration methodology requires the particular consideration of the possible interference not only with the original materials but also with the various superimposed products applied during previous interventions, which cannot be removed due to the fragility of such wall paintings.
The principal matters were, above all, the full comprehension of the complex stratigraphy and of the materials—both the original ones and those added subsequently during the various interventions [8,9]. In this framework, diagnostics was a fundamental method of investigation to clarify several unknown aspects due to the lack of written documentation [10,11]. The restoration performed by our university and completed at the end of 2021 aimed to lead the operation through the minimum intervention approach, avoiding further stress on the already degraded paintings [12,13,14,15]. For these reasons, a scientific approach to the artwork was fundamental in achieving the aim of the restoration [15,16,17,18,19,20,21]. Starting from the well-consolidated methodology of our working team, the analysis of the painting materials started with in situ investigation using non-invasive techniques—specifically, hypercolorimetric multispectral imaging (HMI), ultraviolet fluorescence photography (UVF), and X-ray fluorescence spectroscopy (XRF) [22,23,24,25,26].
Moreover, during the entire period of the restoration activities, microclimate monitoring was performed in the area of the porch in order to determine the environmental conditions to which the wall painting had been acclimated [27].
The in-situ analyses and measurements were accompanied by laboratory investigations of micro-samples taken after the careful non-invasive campaign. This approach helped in the selection of the most appropriate and significant samples and in limiting their number, as an appropriate diagnostic campaign requires [28,29].
The laboratory analyses were carried out via Fourier transform infrared (FTIR) spectroscopy and the stratigraphic study of the samples’ cross-sections.
The direct observation constantly performed during the restoration activities and the study of the written sources and the archived documentation, coupled with diagnostics and analytical tools, allowed us to shed light on the materials, the execution techniques, and the modern restoration of the paintings. Moreover, thanks to the new data collected during the restoration of the wall painting in the porch of the church of St. Andrew, it was possible to establish connections with the pictorial technique of Matteo Giovannetti, an important artist working in the Popes’ Palace in Avignon.
This paper is organized as follows: Section 2 describes the artwork and the main historical information about it and about the porch, as well as the methodology used for the in situ and laboratory analysis; Section 3 reports the data obtained from the analysis and discusses them in relation to the historical context of the painting and the possible previous restorations; and Section 4 presents the synthesis of the main findings and outlines the future development of the research.

2. Materials and Methods

2.1. Historical Sources and Information About the Conservation Aspects of the Wall Painting

Close to the entrance portal of the church of St. Andrew in Pianoscarano, in a room that corresponds to the building’s porch (or portico), there are a few remains of wall paintings executed in different historical periods. Specifically, on the left side with respect to the entrance, we can observe a praying woman and the Madonna del Latte or Virgo Lactans, ascribed, respectively, to the early and mid-14th century (Figure 1) [30].
The wall painting of the Madonna del Latte, although of limited visibility due to its poor state of conservation, has been attributed on the basis of stylistic aspects to the hand of Matteo Giovannetti [30,31], the painter of the Popes’ Palace in Avignon (1343–1367), or to the workshop of the same master [32]. The value of this painting has increased due to the paucity of other artworks left by Matteo Giovannetti in his hometown, Viterbo. In fact, despite several connections proposed with various artefacts in Viterbo’s territory, there are only two artworks directly attributed to his workshop: a crucifixion wall painting in the church of St. Maria Novae [32] and a panel painting with similar iconography in the Cassa di Risparmio bank at Viterbo [32,33,34,35,36,37].
The past modifications applied to the porch profoundly influenced the dynamics of the paintings’ degradation: originally open, the closure of this space seems to have occurred in 1547, along with several other interventions, following a pastoral visit by Cardinal De Gambara [38]. The Cardinal, according to relevant sources, had already ordered an initial intervention for the paintings [38], which were evidently affected by premature degradation only two centuries after their execution, and the closure of the porch was disposed of (Figure 2A). The reasons for this are not clear, but we can affirm that this intervention preserved the artwork, slowing down its degradation until the subsequent reopening in 1945, when further works likely affected the wall painting (Figure 2B) [38].
A photograph, obtained from Federico Zeri’s archive and taken around 1950 [40], compared with a 1981 image captured before the restoration performed by Rossano Pizzinelli in 1982 [41], shows how the deterioration of the paintings—and, in particular, of the Madonna del Latte area—was accelerated exponentially after the reopening of the portico’s infill (Figure 3). The 1950 photograph is particularly important, not only due to the information on the state of conservation but also because it is the only known record of the attribution of Zeri to Matteo Giovannetti [40].
The main evidence when comparing the two images (A and B in Figure 3) is the presence of a dark layer on the surface, appearing in the 1981 photograph, which partially obscured the image. This layer was removed during the restoration of 1982, which included other interventions on the artwork, as reported in the original document written by Pizzinelli and preserved in the archive and photographic laboratory of the Autonomous Institute Vittoriano e Palazzo Venezia [41]. The synthesis of the main interventions and the original archival documents have been also reported in the Master’s degree thesis of Tovazzi [1]. In the historical images, the two angels are still visible on the side of the Virgin, although they are very faint; in contrast, in the recent image (see Figure 1), the only remaining part of the angels is the halo in blue.
Other images collected from various publications clearly show that, despite the important restoration that occurred in 1982, the condition of the paintings inevitably declined, reaching almost total disappearance (Figure 4) [36,42,43]. At the beginning of the restoration performed by the University of Tuscia, the entire surface of the painting appeared covered by a layer of powder and earthy deposits; the pictorial layer was characterized by the presence of extended missing parts and deep abrasions up to the level of the preparatory layers (Figure 4). Moreover, the pictorial layer was extensively detached from the plaster, with widespread spalling phenomena. In addition, the first cleaning tests revealed the presence of some bleaching due to the degradation of the materials applied during previous interventions, which, as outlined in the Introduction, required in-depth investigations [1] (pp. 146–200).

2.2. Hypercolorimetric Multispectral Imaging (HMI) and Ultraviolet Fluorescence Photography (UVF)

The first analysis of the paintings was performed through imaging techniques, specifically HMI and UVF.
HMI is a multispectral method and was performed by Profilocolore (Rome, Italy), composed of three parts.
(1) The acquisition system was composed of a modified digital camera, a Nikon D800 (Nital SpA, Moncalieri Torino, Italy), which captured images in the spectral range of 300 to 1000 nm; three bandpass filters for the selection of the spectral region; a series of white reference patches; a color checker with 36 colors from the Natural Color System (NCS)®© (NCS, Milan, Italy); two modified flashes covering the region from 300 to 1000 nm; and two CR230B-HP 10W UV LED projectors, with peak emission at 365 nm, mounted at 45° with respect to the camera, for the acquisition of the UV-induced fluorescence (UVF). Further details of the acquisition system and procedure are reported in previously published papers [44,45,46,47].
(2) The calibration software named SpectraPick® (v1.1, created by Profilocolore, Rome, Italy) was used to calibrate the images acquired in the previous step. The calibration software processes the .nef files directly produced by the digital camera and, at the end of the process, gives seven .tiff monochromatic images centered at 350, 450, 550, 650, 750, 850, and 950 nm, as well as the RGB output. Calibration is usually performed onsite because it requires about ten minutes, so that, in the event of problems occurring during acquisition, step 1 can be immediately repeated.
(3) The processing software named PickViewer® (v1.0, created by Profilocolore) served as an instrument enabling us to work on the calibrated images. Different tools can be applied to obtain information about painting materials, such as infrared and ultraviolet false color images, chromatic and reflectance similarity maps, principal component analysis (PCA) on selected bands from UV to IR, and so on. The results can be saved as images in tiff, png, or jpeg format.

2.3. X-Ray Fluorescence Spectroscopy (XRF)

XRF analysis was performed onsite by Dr. Claudio Falcucci (M.I.D.A. Company, Rome, Italy) using a portable, in-house-built XRF spectrometer (M.I.D.A. Company, Rome, Italy). The instrument operates with the following settings: Au tube at 40 kV, current at 0.04 mA, and acquisition time equal to 50 s. The instrument was equipped with a Si-PIN detector (resolution 155 eV at 5.9 keV).
Thirty-two points of analysis were selected for XRF measurements in order to characterize the pigments of the original painting layer and the eventual restoration and/or degradation products (Figure 5). Details of each point are reported in the Supplementary Materials (Figures S1–S32).

2.4. Temperature and Relative Humidity Monitoring During the Restoration

The monitoring of the temperature and relative humidity (%RH) was performed by using a robust datalogger, Testo Model 175-H2 (Testo SpA, Settimo Milanese, Milan, Italy), at the frequency of 1 datum every 60 min. The temperature and relative humidity accuracy, resolution, and range of the used sensor were the following: temperature range of −20 to 70 °C with accuracy 0.5 °C and resolution 0.1 °C; %RH range of 0 to 100% with accuracy 3% and resolution 0.1%.

2.5. Fourier Transform Infrared Spectroscopy (FTIR)

FTIR analysis was performed through a Nicolet Avatar 360 spectrometer supplied by Thermo Fisher Scientific (Waltham, MA USA). The spectrometer was equipped with an IR source and a deuterated try-glycine sulfate (DTGS) detector and operated in the mid-IR spectral range between 400 and 4000 cm−1 with a resolution of 4 cm−1. For each sample, 128 scans were acquired in the diffused reflectance (DRIFT) modality. To operate this accessory, the samples were ground with potassium bromide (KBr) in an agate mortar. Salt was also used as background material. The acquired spectra were post-processed through the software OMNIC 8.0 supplied by Thermo Fisher Scientific (Waltham, MA USA). Seven samples were examined through FTIR spectroscopy (samples S1–S7, see Figure 6). The DRIFT modality for the acquisition of spectra is well consolidated and widely applied within our research team for the analysis of materials both related to cultural heritage and to other fields, so we have a relevant internal database of DRIFT-FTIR spectra of compounds of cultural heritage interest. This is useful in supporting the identification of materials in complex mixtures, such as those generally found in artworks [48,49,50].

2.6. Microstratigraphic Analysis Under Optical Microscope

Four micro-samples (S7–S10, see Figure 6 for sample locations) were selected and taken from the wall painting to prepare cross-sections for microscopic examination, with marginal portions of the artwork chosen or those close to pre-existing lacunae. Sample cross-sections were prepared by LabSTONE snc (Palermo, Italy) after the micro-samples were embedded in a resin, suitably cut, and polished. The prepared cross-section was observed via a polarized light microscope, the Zeiss Axioskop, equipped with reflected, transmitted, and UV lighting. The images were acquired through the Zeiss AxioCam NRc (Zeiss, Oberkochen, Germany) camera and processed using the AxioVision software, version 4.7, to trace the sequence of the stratigraphic layers and to identify possible traces of organic material or the characteristic fluorescence of materials by means of observation via ultraviolet radiation.

3. Results

As underlined in Section 2.1, the investigated wall paintings underwent several interventions starting shortly after their execution, as determined from our careful observations during the restoration. In particular, the Virgo Lactans’ background is characterized by many pictorial layers and a superficial bleached appearance. The analysis of this layer’s paintings was conducted by starting with non-invasive multispectral imaging techniques performed with portable instrumentation and subsequently with the addition of micro-invasive techniques (FTIR and cross-sections under optical polarizing microscope). The aims of this analysis were (1) clarify the execution technique of the Virgin painting so as to reconstruct the original palette and to distinguish the added pictorial layers, included the protective modern coating; (2) to match the various interventions with those deduced from bibliographic research and perform a comparison with the history of the pigments and materials themselves; (3) to analyze the case of the missing angels on either side of the Virgin, seeking to determine their origin and the causes of their disappearance; (4) to address some questions raised during the observation of the scene attributed to the Viterbo master, Matteo Giovannetti, through the comparison of the Virgo Lactans’ original pigments with those found in Matteo Giovannetti’s paintings in the Avignonese Popes’ Palace. All data collected during the analysis were compared with those inferred from transcriptions of the worksite diary of Matteo Giovannetti himself, which was written during the decoration of the Consistory Hall in 1347 in Avignon [51].

3.1. HMI and UVF

The HMI processing software supplied some data about the Virgin scene, confirming the complex stratigraphy and the layers’ superimposition. The response in terms of infrared false colors (IRFC) and ultraviolet false colors (UVFC) allowed to identify the use of azurite for the blue in the Virgin’s dress, in the haloes visible on the sides of the Virgin, and in the background (Figure 7). Azurite shows a dark blue or brown color in IRFC and a green hue in UVFC [52,53]. Another hypothesis based on false colors was derived for the reds and yellows visible in the frame of the scene and in the haloes. These responses are typical of natural iron oxide pigments: light yellow in IRFC and violet in UVFC.
Further processing was performed to compare the blue color of the Virgin’s dress and that of the angels’ haloes, which appear differently in visible light.
The results of the reflectance and chromatic comparison are shown in Figure 8. The two colors exhibit significantly different reflectance values, especially in the 450 nm band (11.72 and 22.36%) and in the 950 nm band (18.78 and 26.45%). The xy coordinates also show a clear difference between the two blue colors, where that of the Virgin’s dress is less saturated and bright. This result suggests that the blue of the Virgin is more degraded with respect to the blue of the halo. The latter was applied over the yellow of the halo and indicates clear inpainting.
The UVF acquisitions were performed in order to obtain more information about the original technique of the painting and to attempt the identification of any protective or superimposed materials on the surface. By observing the UVF image, a dark and non-homogenous surface emerges, suggesting a poor state of conservation and the presence of several interventions (Figure 9). In general, the surface appears quite dark, mainly on the left side corresponding to the figure of the praying saint, with some spotted or diffuse fluorescence visible in the throne and at the lower edge of the painted scene. This is probably due to the presence of protective restoration and inpainting, which generally appear dark under UVF, and to the various interventions applied to the painting [54,55,56]. In the detailed image shown in Figure 9B, it is possible to observe intense yellow fluorescence localized within the halo of the angel on the left of the Virgin. Some hypotheses can be proposed to explain this inhomogeneous, intense fluorescence. It can be attributed to the presence of the mixture used to glue the gilding (the so-called missione, composed of siccative oils and natural terpenic resins) [47,57,58]. However, it could be due also to superimposed layers applied during past restorations. Further analysis will confirm this. The light blue fluorescence visible in various zones of the painting, especially in the lower part, may be associated with the calcium carbonate present in the mortars and in the flesh tones where it is used as a pigment.

3.2. XRF Results

The first step of the diagnostic procedure allowed us to gather an overall view of the painting in terms of the materials and state of preservation, as well as enabling the XRF point analysis and the sampling for the laboratory investigation.
XRF spectroscopy, applied non-invasively onsite, allowed a broad view of the chemical elements in the thirty-two examined points, chosen to cover all possible colors visible in the wall paintings. The results are summarized in Table 1. Based on the elements revealed, it is possible to identify the type or types of pigments used by the artist and during subsequent restoration interventions to obtain the various colors and shades. Pigments exclusively containing elements with a low atomic number (in our case, less than 19), such as all organic pigments and ultramarine blue, cannot be identified. The presence of these pigments can, however, generally be deduced from the absence, at the analyzed point, of other pigments of the same color. It should also be noted that, as it is based on the identification of chemical elements, XRF analysis is not able to distinguish between pigments of the same color and with a very similar chemical composition, such as verdigris, malachite, and copper resinate. In these cases, only the presence of copper will be highlighted. The results of the XRF analysis, presented in the form of counts, cannot be interpreted in a quantitative sense but only qualitatively or semi-quantitatively due to the characteristic inhomogeneities of pictorial layers and the absolute non-destructiveness of this type of analysis. Because the results could not be interpreted in a quantitative sense, it was not considered appropriate to carry out numerical corrections related to the excitation efficiencies, the production of fluorescence photons, and the detection of the different elements [59,60].
The data shown in Table 1 indicate the presence of common elements such as calcium (Ca), rubidium (Rb), strontium (Sr), zirconium (Zr), and iron (Fe). These elements are commonly detected in wall paintings, being associated with the components of the mortars (binder and aggregates) [26]. Iron was detected in high counts in correspondence to red and yellow areas, where it could be associated with iron oxide-based pigments (points 21, 22, 23, and 31). In some blue areas (points 3 and 4), the presence of iron could be associated with Prussian blue, which was clearly used as a restoration pigment starting in the beginning of the 18th century [61]. Calcium is probably linked also to a white pigment used to obtain light hues, such as those corresponding to the flesh (points 24 and 25). In fact, Ca is the white component of calcium carbonate, a material that has been widely used as a pigment in wall paintings since antiquity [62].
As derived from the data in Table 1, lead white has been also used in the wall paintings of St. Andrew’s porch. In fact, lead is revealed in almost all measured points, sometimes with high counts (points 6, 7, 15, 16, 17, and 32). The presence of lead white, a basic Pb carbonate, suggests the use of a secco technique, which is confirmed using copper-based pigments and vermilion/cinnabar (mercury, Hg, detected at points 19, 20, 23, and 32). These materials, in fact, cannot be used in a fresco application due to the alkaline nature of the binder. Thus, part of the painting was produced by fresco, such as the flesh hues, and it was preserved, while the secco parts were detached and underwent restoration and inpainting. Cu was detected at several points consisting of blue and green colors, suggesting the use of azurite, malachite, and possibly other copper-based pigments.
The presence of cobalt (Co) at point 5, which is a green–blue color, may be due to the presence of cobalt blue, used as a restoration pigment. Cobalt blue is in fact a synthetic pigment that was introduced in the painter’s palette starting in the 19th century [63].
The presence of tin (Sn) at point 15, which corresponds to bright yellow in the halo of the angel and is visible in traces in the light blue color of the halo (Figure S15), may be associated with lead tin yellow, a lead stannate pigment [64].
Lastly, gold (Au) was detected in traces (due to low counts) in the halo of the Virgin, indicating the presence of some remains of the original gilding. This part of the wall painting is particularly deteriorated and has been affected by various interventions, making it difficult to analyze the stratigraphy and the original appearance (see Figures S27–S31).

3.3. Temperature and Relative Humidity Monitoring

The onsite activity included also the monitoring of the relative humidity and temperature for the entire year of the restoration. The porch environment was semi-confined, and the values of the two monitored parameters clearly depended on seasonal trends, as can be observed in the graphs shown in Figure 10 and Figure 11.
The strong variations in the relative humidity (Figure 10) due to climate changes, especially in the winter, sometimes reaching 100%, were the main factor responsible for the poor state of conservation of the paintings.
The temperature values showed the typical trend found in semi-confined environments and associated with seasonal variations [27].
Monitoring campaigns are relevant in cultural heritage preservation and conservation, firstly to identify the materials used for restoration and secondly to determine the historical climate to which the artwork has adapted over time, as indicated in the international standard published by the technical committee, CEN/TC 346—Conservation of Cultural Property [65]. The historical climate is relevant both in better understanding the degradation patterns observed on the wall painting’s surfaces and in eventually proposing solutions for mitigation purposes. In cases such as that of the porch of St. Andrew, it is difficult to change the qualities of the environment, but a partial closure may be considered.

3.4. FTIR Data

FTIR spectra were obtained for seven selected samples taken from the paintings. The data are summarized in Table 2, and the spectra are shown in Figures S33–S39.
Some recurring materials have been identified in the FTIR spectra. Specifically, these are gypsum, which can be associated with the restoration materials used for the grouting and filling of lacunae during previous restoration works; calcium carbonate, which was the main component of the mortar and binder of the pigments applied via the fresco technique; copper and probable calcium oxalates as degradation materials; azurite, which is confirmed as the pigment used for the blue color; and some different organic compounds. In sample S6, the presence of calcium carbonate is relevant, and the two usually absent or very weak signatures at 2987 and 2873 cm−1 are evident in the spectrum shown in Figure S38 [66,67]. The C=O signature at about 1730 cm−1, visible in almost all spectra, may be associated with the synthetic resin used in the last intervention (probably Paraloid B72, as indicated in the restoration report of 1982, written by the restorer Rossano Pizzinelli and stored in the archive and photographic laboratory of Instituto Autonomo Vittoriano e Palazzo Venezia in Rome).
Other organic materials were found in sample S7, corresponding to the halo of the angel, where UVF photography gave a yellow response. This is hypothesized to indicate the presence of a combination of lipidic and protein materials, which were used as binders for the lead/tin yellow pigment and azurite or as a surface protectant applied in past restorations. This is also indicated by the intense fluorescence induced by UV radiation (UVF photography).

3.5. Cross-Section Observation

The onsite diagnostic campaign and the laboratory investigation of the micro-samples through FTIR allowed us to obtain several useful and interesting data about the painting materials and the degradation products, but some further details could be obtained from the cross-sections. The investigation of the stratigraphy pattern of the wall painting is relevant in better understanding the execution technique and the distributions of the materials detected by XRF and FTIR spectroscopy.
Let us start with the stratigraphy of the angel’s halo, where the XRF revealed the presence of copper, tin, and lead and confirmed the absence of gold. A cross-section of a micro-sample taken from this area is shown in Figure 12.
By observing the cross-section in Figure 12B, it can be seen that a blue layer of azurite (number 1) is located under the yellow layer (number 2) composed of a Pb-/Sn-based pigment. Only a few grains of azurite are visible in the cross-section (as indicated by 1 in Figure 12B). This suggests that the halo was painted over the layer of azurite constituting the background and that the painting layers were detached from the plaster. In this case, the yellow color of the gilding was obtained by using a brilliant lead- and tin-based pigment instead of gold. Above the yellow layer (number 2), there is a complex situation. The dark and obscure layer visible in Figure 12B can be separated into two parts thanks to ultraviolet radiation (Figure 12C, layers 3 and 4). In fact, layers 3 and 4 appear fluorescent under UV radiation: the lower one (directly above the Pb/Sn yellow, number 3) exhibits yellowing fluorescence and the upper part (number 4, which is partially detached from the lower part) shows light blue fluorescence. This thick layer can be attributed to protectives applied in past restorations, when it was common to apply mixtures of compounds or synthetic resins to protect and refresh such wall paintings [68,69,70,71]. These data confirm the results obtained by the FTIR analysis of sample S7. On the surface, a fifth dark layer could be observed. This layer, without fluorescence under UV, could be attributed to dirt deposited on the painting.
Another sample examined in the cross-section analysis was S8, taken from the halo of the Virgin, with the aim of comparing it with that gathered from the angel’s halo. In this case, the stratigraphy was more complex and difficult to interpret due to the various partially mixed layers, which probably occurred during the cutting of the sample to obtain the cross-section (Figure 13). This was probably caused by the fragmentary and unconnected nature of the wall paintings, which were in a very poor state of conservation, as previously noted.
Nevertheless, by carefully observing the cross-section, it was possible to distinguish seven layers. Starting from the bottom, we identified an azurite layer (1 in Figure 13B) that constituted the background over which the halo was painted. Moreover, in this case, the painting layers appear detached from the plaster support, indicating the poor state of conservation of the artwork and the necessity of consolidation. Layer 2 was the setting for the first gilding (layer 3), which was almost completely lost. Over this first gilding, it was possible to distinguish a brown layer (number 4) and subsequently further gilding (layers 5 and 6, where 5 was the setting and 6 consisted of the remains of the gold leaf).
Lastly, a discontinuous surface layer (number 7) was characterized by a light-yellow color and pale bluish fluorescence under UV radiation. This layer may be associated with the most recent restoration intervention.
To further analyze the complex stratigraphy of the painting, especially in correspondence to the Virgin’s halo and crown, another cross-section was examined (Figure 14).
In fact, immediately below the halo of the Virgin was another point of great stratigraphic interest, namely the ring-shaped crown supported by spikes, of which only a few fragments and traces of incisions remain. Here, micro-sample S9 was obtained at the point shown in Figure 14A.
As in the case of the previous sample’s (S8) stratigraphy, the sequence of the layers was difficult to differentiate due to the partial interpenetration of one layer with another and to the loss of pictorial matter. We could distinguish six layers, as indicated in Figure 14B. Layer 1 was composed of azurite, which constituted the background on which the crown was created. The painting layer was detached from the plaster support, indicating the poor state of conservation of the artwork and the necessity of consolidation. Layer 2, exhibiting pale yellow fluorescence under UV, which was probably due to the presence of organic compounds, was the setting for the first metal foil application (layer 3), which appeared dark. Over this first metal layer, it was possible to distinguish a grey layer (number 4) and traces of gilding (layers 5), covered by traces of the most recent yellow painting (layer 6).
The last examined cross-section concerned micro-sample S10, taken from the right-side background of the Virgin’s scene, where the sequence of the layers appeared to be more visible (Figure 15). The reading of the stratigraphy provided the most important data about the technique and the sequence of the various interventions.
In the sample cross-section, some residues of the plaster are observed (layer 1), which are partially detached from the first painting layer of the grey color (layer 2); this was the setting for the original background, painted with azurite by the secco technique (layer 3, almost completely detached from layer 2). In layer 3, azurite was mixed with a white pigment, probably lead white (as derived from the XRF data), to obtain a light blue color. A subsequent layer of blue painting (layer 5) was applied on layer 3, separating this by means of a transparent material exhibiting orange fluorescence (layer 4). Due to the precious nature of the blue azurite pigment used for the intervention pertaining to layer 5, it may be hypothesized that this intervention coincided temporally with the first remaking of the Virgin’s halo and crown, executed with gold leaf. The occasion of this ancient restoration was probably the intervention commissioned by Cardinal de Gambara in 1574 [38]. Finally, layer 6, characterized by a dark blue color and probably composed of Prussian blue, was related to the second ancient intervention executed on the wall painting around the 18th–19th century, which included also the yellow ochre painting applied to various parts of the surface and visible in the cross-sections of samples S7–S9 [41].
The analysis of the polished sections, despite proving very difficult due to the various layers, which were sometimes partially interpenetrated and detached from each other, shed light on the complex stratigraphy of the painting and on the possible interventions carried out in ancient times, for which, unfortunately, there is no reference bibliography but only a few archival sources.

4. Discussion

The different analyses performed on the wall paintings of the porch in the church of St. Andrew in Viterbo allowed us to obtain information that contributes to our knowledge of the artwork; in particular, it allows us to suggest its attribution to Matteo Giovannetti’s workshop, to distinguish the original paintings from the subsequent interventions, and to support our recent restoration.
The painting is composed of two scenes: one representing a praying figure and the other the Virgin (Virgo Lactans), which stylistically appears somewhat different. The analysis was mainly focused on the scene with the Virgin, but HMI and some XRF points were applied also to the praying figure scene. Similar pigments were detected in the two scenes, indicating that they were probably created at the same or a similar time. The differences between the two scenes concerned only some technical aspects, such as the drawing of the haloes (by stamp for the praying figure and by punching for the Virgin) and the number of working days (single for the praying, multiple for the Virgin scene) [1] (pp. 70–75).
Among the most relevant issues to be clarified was the identification of the previous restorations. In fact, the only documented interventions on these wall paintings are those commissioned by Cardinal De Gambara in 1574 [38] and the one dating back to 1981 and performed by Pizzinelli [41]. The close observation of the surfaces during the last restoration and the analysis, however, led to an alternative conclusion. In particular, a third intervention was identified, performed in the period between the two above-mentioned ones, according to the stratigraphic pattern. The first intervention, dating back to the period of Cardinal De Gambara (about 1574), included the application of a layer of azurite and of a new layer of gold in the haloes of the Virgin’s scene.
The second, undocumented intervention discovered in the present study was carried out in the period between 1700 and 1900 and was identified through the yellow ochre painting in the Virgin scene and the blue color composed of Prussian blue (background) and cobalt blue (the Virgin’s dress). This intervention may also have involved some grouting between the two scenes (the praying figure and the Virgin) and a white scialbo visible in traces on the lower part of the praying figure’s dress. This assessment was based on the close observation of the painted surfaces during our restoration activities.
The discussion of ancient interventions immediately leads back to one of the most complex issues regarding the Virgin scene: the origins of the kneeling angels. It must be noted that their unpreserved state has misled some of the scholars who have studied this painting. These angels were interpreted as being located “behind the back” of the throne, and the last photograph of them could be found in the Zeri archive, where they appeared as shreds of color. The observation of the angels from the scaffolding, during the last restoration, showed that the halo’s incision shape was created on dry plaster; this was due to the irregularity of the strokes and the condition of the paint film at the edges. The profiles of the two angels are perfectly mirrored, probably due to the use of a cardboard cutout to transfer the drawing to the wall. One interesting aspect, confirmed by the stratigraphic analysis shown in Figure 12, is the azurite blue background applied when the 1547 restoration was painted around the angels, without covering them. This finding seems to support the originality of the angels. In fact, if the angels’ execution coincided with the 1547 intervention, they would have been painted over the new blue background layer, as was the case for the first phase of the background. Moreover, the presence of angels in the iconographic pattern of the Nursing Virgin was quite common in medieval times; this supports the identification of the angels as original.
The last issue to be discussed is related to the comparison of the execution technique and materials of the painting on the St. Andrew’s porch to those of the works of Matteo Giovannetti in the Palace of Avignon in France, suggesting its attribution to this medieval master. An initial analysis had already been carried out during a Master’s thesis, carefully comparing the distinctive features of the Johannite portraiture in the French location, finding clear similarities with the face of the Virgin of St. Andrew’s church, especially regarding the treatment of the hair, the facial features, and the pictorial layers [1] (pp. 82–87).
The data collected in the present study were compared with those reported for the paintings of Avignon by Eileen Kane and derived from Matteo Giovannetti’s diary [48]. The comparison between the two artworks is shown in Table 3.
As we can observe in Table 3, there is great similarity in the pigments used for the two paintings, with some small differences. In particular, the paintings of Avignon exhibit a richer palette than the Nursing Virgin scene in Viterbo, probably due to the wider extension of the surfaces and to the better state of preservation, as well as to the client’s greater economic resources. In Viterbo, in fact, the highly compromised state of the painting’s surface may have been caused by the loss of some colors, especially those applied by the secco technique [2,6].
The immediate similarities that can be seen, however, concern the construction of the palette: in both cases, the same shades of color pigments applied with both techniques, i.e., fresco and secco, were chosen by the artist. For example, regarding the red hues, in both paintings, iron-based pigments were applied via the fresco technique, and vermilion/cinnabar, which are incompatible with fresco, were used. The same is true for the yellow nuances, created with an iron hydroxide pigment (yellow ochre), which is compatible with the fresco technique, and orpiment (arsenic sulfide), which was applied by secco. Eileen Kane, referring to Avignon’s painting, considers this choice a premeditated decision by the artist, who could take advantage of a wider range of pigments in comparison to those compatible with the pure fresco method, allowing them to create several hues and surface finishing details using secco [51]. This assertion may also be applicable to the St. Andrew wall painting, strongly suggesting that it can be attributed to Matteo Giovannetti.
In conclusion, despite the compromised state of the wall paintings in the porch of St. Andrew’s church, the combined use of archival sources, direct careful observation, and the analyses performed during our last restoration allowed us to characterize the pigments used by the medieval artist and to distinguish at least three main previous interventions (two ancient and one more recent), including one that had never been considered before.
The characterization of the pigments and their combined use, compared with those used in the Palace of Avignon by Matteo Giovannetti in 1347, allowed us to identify clear similarities, supporting the attribution of the Viterbo painting to this important medieval master and his workshop.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/heritage8020064/s1, Figure S1: XRF point 1: dark background near the angel’s halo; Figure S2: XRF point 2: bright and light blue color of the right angel’s halo; Figure S3. XRF point 2: blue color of the background, behind the Virgin; Figure S4. XRF point 4: black on blue color of the background, behind the Virgin; Figure S5. XRF point 5: Virgin’s mantle, on the shoulder. Possible alteration of surface protective coating; Figure S6. XRF point 6: possible hand of the angel kneeling to the left of the Virgin. Greenish color on light blue; Figure S7. XRF point 7: possible hand of the angel kneeling to the left of the Virgin. Light blue under the greenish surface layer; Figure S8. XRF point 8: light green point on the Virgin’s garment; Figure S9. XRF point 9: black color on a probable yellow frame; Figure S10. XRF point 10: yellow color of the frame, under the black of the previous point; Figure S11. XRF point 11: black color on grouting; Figure S12. XRF point 12: black color on grouting; Figure S13. XRF point 13: light green color of the angel’s dress; Figure S14. XRF point 14: yellow color of the Virgin’s hair; Figure S15. XRF point 15: bright yellow color under the light blue of the angel’s halo; Figure S16. XRF point 16: yellow color on the light blue of the angel’s halo; Figure S17. XRF point 17: yellow spot on the Virgin’s garment; Figure S18. XRF point 18: yellow color of the angel’s dress near the left hand of the praying person; Figure S19. XRF point 19: red color of the Virgin’s dress, in correspondence to the chest. Red is applied to a light-colored background; Figure S20. XRF point 20: dark red color of the Virgin’s dress, in correspondence to the chest; Figure S21. XRF point 21: red color of the frame, left of the throne; Figure S22. XRF point 22: red color of the decoration pattern in the throne; Figure S23. XRF point 23: red color of the frame, upper part of the scene; Figure S24. XRF point 24: flesh hue of the Virgin’s nose; Figure S25. XRF point 25: flesh hue of the hand of the praying person; Figure S26. XRF point 26: green color of the angel on the right of the praying person; Figure S27. XRF point 27: black color on the halo of the Virgin; Figure S28. XRF point 28: yellow color on the halo of the Virgin; Figure S29. XRF point 29: yellow color on the halo of the Virgin, possible inpainting; Figure S30. XRF point 30: yellow color on the halo of the Virgin, radial decoration; Figure S31. XRF point 31: yellow–orange color on the halo of the Virgin, possible restoration; Figure S32. XRF point 32: brown color on the frame, left side of the Virgin scene; Figure S33: FTIR spectrum in diffuse reflectance modality of sample S1; Figure S34: FTIR spectrum in diffuse reflectance modality of sample S2; Figure S35: FTIR spectrum in diffuse reflectance modality of sample S3; Figure S36: FTIR spectrum in diffuse reflectance modality of sample S4; Figure S37: FTIR spectrum in diffuse reflectance modality of sample S5; Figure S38: FTIR spectrum in diffuse reflectance modality of sample S6; Figure S39: FTIR spectrum in diffuse reflectance modality of sample S7.

Author Contributions

Conceptualization, C.P., M.G. and V.T.; methodology, L.L. and M.G.; software, L.L.; validation, C.P., L.L. and V.T.; formal analysis, C.P., L.L. and C.F.; investigation, L.L., C.P., C.F. and V.T.; resources, C.P.; data curation, V.T., L.L. and C.F.; writing—original draft preparation, C.P., V.T. and C.F.; writing—review and editing, all authors; visualization, L.L., V.T. and C.F.; supervision, C.P. and M.G.; project administration, C.P., V.T. and M.G.; funding acquisition, C.P. and M.G. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

No further data available.

Acknowledgments

The authors would like to thank the Municipality of Viterbo for having funded the restoration of the painting; the Parish of St. Andrew for its availability and support during the work; the Soprintendenza Archeologia, Belle Arti, Paesaggio per l’Area Metropolitana di Roma, la Provincia di Viterbo e l’Etruria e Archivio e Laboratorio Fotografico Istituto Autonomo Vittoriano e Palazzo Venezia, which supplied the archive photographs, and the professional photographer Gaetano Alfano for the documentation photography during the various phases of the restoration.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Tovazzi, V. Studio e Restauro di Due Dipinti di sec. XIV nel Portico della Chiesa di Sant’Andrea a Viterbo. L’attribuzione della Madonna del Latte all’Ambito di Matteo Giovannetti. Master’s Thesis, University of Tuscia, Viterbo, Italy, November 2021. [Google Scholar]
  2. Jiménez-Desmond, D.; Pozo-Antonio, J.S.; Arizzi, A. The fresco wall painting techniques in the Mediterranean area from Antiquity to the present: A review. J. Cult. Herit. 2024, 66, 166–186. [Google Scholar] [CrossRef]
  3. Rockwell, C. (Ed.) Western Medieval Wall Paintings: Studies and Conservation Experience: Sighisoara, Romania, 31 August–3 September 1995; ICCROM: Rome, Italy, 1997. [Google Scholar]
  4. Schädler-Saub, U. “Bildtapeten” and the Conservation of Medieval Wall Paintings at the Turn of the Twentieth Century in Germany. New Perspectives in the Conflict Between Authenticity and Visual Integrity. CeROArt, HS 2013. Available online: https://journals.openedition.org/ceroart/3551 (accessed on 23 May 2024).
  5. Fras, E.M. Challenges of Conservation and Restoration of a Medieval Wall Painting in the Church of Saint Leonard in Mala Ligojna and the Question of Its Authorship. Acta Acad. Artium Vilnensis 2023, 108, 158–191. [Google Scholar] [CrossRef]
  6. Murat, Z. Wall paintings through the ages: The medieval period (Italy, twelfth to fifteenth century). Archaeol. Anthropol. Sci. 2021, 13, 191. [Google Scholar] [CrossRef]
  7. Brajer, I. Values and Opinions of the General Public on Wall Paintings and Their Restoration: A Preliminary Study. Stud. Conserv. 2008, 53 (Suppl. S1), 33–38. [Google Scholar] [CrossRef]
  8. Mugnaini, S.; Bagnoli, A.; Bensi, P.; Droghini, F.; Scala, A.; Guasparri, G. Thirteenth century wall paintings under the Siena Cathedral (Italy). Mineralogical and petrographic study of materials, painting techniques and state of conservation. J. Cult. Herit. 2006, 7, 171–185. [Google Scholar] [CrossRef]
  9. Fico, D.; Pennetta, A.; Rella, G.; Savino, A.; Terlizzi, V.; De Benedetto, G.E. A combined analytical approach applied to Medieval wall paintings from Puglia (Italy): The study of painting techniques and its conservation state. J. Raman Spectrosc. 2016, 47, 321–328. [Google Scholar] [CrossRef]
  10. Salatino, G.; Zicarelli, M.A.; Ricca, M.; Macchia, A.; Randazzo, L.; Pogliani, P.; Arcudi, A.; Ruffolo, S.A.; La Russa, M.F. A Multi-Analytical Diagnostic on an Outdoor Wall Painting: The Study on the Déesis of St. Maria Annunziata’s Church, Motta San Giovanni (Reggio Calabria, Italy). Appl. Sci. 2023, 13, 10439. [Google Scholar] [CrossRef]
  11. Philippova, O.S.; Dmitriev, A.Y.; Tsarevskaya, T.J.; Makarova, A.-M.L.; Grebenshchikova, A.B. Medieval mural painting: A look through the centuries. J. Cult. Herit. 2023, 62, 460–469. [Google Scholar] [CrossRef]
  12. Scott, D.A. Art Restoration and Its Contextualization. J. Aesthetic Educ. 2017, 51, 82–104. [Google Scholar] [CrossRef]
  13. Zhang, Y.; Dong, W. Determining Minimum Intervention in the Preservation of Heritage Buildings. Int. J. Architect. Herit. 2021, 15, 698–712. [Google Scholar] [CrossRef]
  14. Pelosi, C.; Di Stasio, F.; Lanteri, L.; Zuena, M.; Sardara, M.; Sodo, A. The “Restoration of the Restoration”: Investigation of a Complex Surface and Interface Pattern in the Roman Wall Paintings of Volsinii Novi (Bolsena, Central Italy). Coatings 2024, 14, 408. [Google Scholar] [CrossRef]
  15. Bergamonti, L.; Graiff, C.; Simeti, S.; Casoli, A. The 20th Century Wall Paintings in the Chapel of the Fallen in Parma Cathedral (Italy): Scientific Investigations for a Correct Conservation Project. Appl. Sci. 2023, 13, 7235. [Google Scholar] [CrossRef]
  16. Ricca, M.; Alberghina, M.F.; Houreh, N.D.; Koca, A.S.; Schiavone, S.; La Russa, M.F.; Randazzo, L.; Ruffolo, S.A. Preliminary Study of the Mural Paintings of Sotterra Church in Paola (Cosenza, Italy). Materials 2022, 15, 3411. [Google Scholar] [CrossRef] [PubMed]
  17. Amura, A.; Aldini, A.; Pagnotta, S.; Salerno, E.; Tonazzini, A.; Triolo, P. Analysis of Diagnostic Images of Artworks and Feature Extraction: Design of a Methodology. J. Imaging 2021, 7, 53. [Google Scholar] [CrossRef]
  18. Bracci, S.; Bartolozzi, G. Wall paintings—Diagnostic and archaeometric studies. Phys. Sci. Rev. 2019, 4, 20180013. [Google Scholar] [CrossRef]
  19. Cortea, I.M.; Ratoiu, L.; Ghervase, L.; Țentea, O.; Dinu, M. Investigation of Ancient Wall Painting Fragments Discovered in the Roman Baths from Alburnus Maior by Complementary Non-Destructive Techniques. Appl. Sci. 2021, 11, 10049. [Google Scholar] [CrossRef]
  20. Catapano, I.; Ludeno, G.; Cucci, C.; Picollo, M.; Stefani, L.; Fukunaga, K. Noninvasive Analytical and Diagnostic Technologies for Studying Early Renaissance Wall Paintings. Surv. Geophys. 2020, 41, 669–693. [Google Scholar] [CrossRef]
  21. Alberghina, M.F.; Milazzo, G.; Schiavone, S.; Randazzo, L.; Ricca, M.; Rovella, N.; Spatafora, F.; Fiorenza, E.; La Russa, M.F. The Contribution of Microchemical Analyses and Diagnostic Imaging to the Conservation and Identification of the Degraded Surfaces of Hellenistic-Roman Wall Paintings from Solunto (Sicily). Stud. Conserv. 2021, 66, 342–356. [Google Scholar] [CrossRef]
  22. Vettraino, R.; Valentini, V.; Pogliani, P.; Ricci, M.; Laureti, S.; Calvelli, S.; Zito, R.; Lanteri, L.; Pelosi, C. Multi-Technique Approach by Traditional and Innovative Methodologies to Support the Restoration of a Wall Painting from the 16th Century at Palazzo Gallo in Bagnaia, Viterbo, Central Italy. Buildings 2023, 13, 783. [Google Scholar] [CrossRef]
  23. Ricci, M.; Laureti, S.; Malekmohammadi, H.; Sfarra, S.; Lanteri, L.; Colantonio, C.; Calabrò, G.; Pelosi, C. Surface and Interface Investigation of a 15th Century Wall Painting Using Multispectral Imaging and Pulse-Compression Infrared Thermography. Coatings 2021, 11, 546. [Google Scholar] [CrossRef]
  24. Madariaga, J.M.; Maguregui, M.; Castro, K.; Knuutinen, U.; Martínez-Arkarazo, I. Portable Raman, DRIFTS, and XRF Analysis to Diagnose the Conservation State of Two Wall Painting Panels from Pompeii Deposited in the Naples National Archaeological Museum (Italy). Appl. Spectrosc. 2016, 70, 137–146. [Google Scholar] [CrossRef] [PubMed]
  25. Groppi, F.; Vigliotti, D.; Lanteri, L.; Agresti, G.; Casoli, A.; Laureti, S.; Ricci, M.; Pelosi, C. Advanced documentation methodologies combined with multi-analytical approach for the preservation and restoration of 18th century architectural decorative elements at Palazzo Nuzzi in Orte (Central Italy). Int. J. Conserv. Sci. 2021, 12, 921–934. [Google Scholar]
  26. Colantonio, C.; Lanteri, L.; Bocci, R.; Valentini, V.; Pelosi, C. “A Woman Clothed with the Sun”: The Diagnostic Study and Testing of Enzyme-Based Green Products for the Restoration of an Early 17th Century Wall Painting in the Palazzo Gallo in Bagnaia (Italy). Appl. Sci. 2023, 13, 12884. [Google Scholar] [CrossRef]
  27. Ferrarese, S.; Bertoni, D.; Golzio, A.; Lanteri, L.; Pelosi, C.; Re, A. Indoor Microclimate Analysis of the San Panfilo Church in Tornimparte, Italy. Appl. Sci. 2023, 13, 6770. [Google Scholar] [CrossRef]
  28. Zicarelli, M.A.; La Russa, M.F.; Alberghina, M.F.; Schiavone, S.; Greca, R.; Pogliani, P.; Ricca, M.; Ruffolo, S.A. A Multianalytical Investigation to Preserve Wall Paintings: A Case Study in a Hypogeum Environment. Materials 2023, 16, 1380. [Google Scholar] [CrossRef]
  29. Andreotti, A.; Izzo, F.C.; Bonaduce, I. Archaeometric Study of the Mural Paintings by Saturnino Gatti and Workshop in the Church of San Panfilo, Tornimparte (AQ): The Study of Organic Materials in Original and Restored Areas. Appl. Sci. 2023, 13, 7153. [Google Scholar] [CrossRef]
  30. Zeri, F. La mostra della pittura viterbese. Boll. D’arte 1955, 4, 85–91. [Google Scholar]
  31. Zeri, F. Un cimelio di Matteo Giovannetti. In Diari di Lavoro; Zeri, F., Ed.; Einaudi: Torino, Italy, 1976; Volume 2, pp. 11–14. [Google Scholar]
  32. Faldi, I. Pittori Viterbesi di Cinque Secoli; Cassa di Risparmio della Provincia di Viterbo: Viterbo, Italy, 1970; pp. 4–7. [Google Scholar]
  33. Castelnuovo, E. Un Pittore Italiano alla Corte di Avignone. Matteo Giovannetti e la Pittura in Provenza nel Secolo XIV, 1st ed.; Einaudi: Torino, Italy, 1962; p. 74. [Google Scholar]
  34. Pace, V. Pittura del Duecento e del Trecento a Roma e nel Lazio. In La Pittura in Italia, Il Duecento e il Trecento; Bertelli, C., Ed.; Electa: Milano, Italy, 1986; Volume 2, p. 440. [Google Scholar]
  35. Polo, G. Il pittore Matteo Giovannetti, da Viterbo ad Avignone nel Trecento. In Pittori, Architetti, Scultori Laziali nel Tempo, 1st ed.; Lefevre, L., Ed.; F.lli Palombi: Rome, Italy, 1954; pp. 43–53. [Google Scholar]
  36. Romano, S. Eclissi di Roma, Pittura Murale a Roma e nel Lazio da Bonifacio VIII a Martino V (1295–1431); Argos: Roma, Italy, 1992; pp. 280–282, 330. [Google Scholar]
  37. Rinaldi, S.; Ricci, F. Museologia e Storia dell’Arte nella Tuscia; Archeoares: Viterbo, Italy, 2014; pp. 105–109, 114–115. [Google Scholar]
  38. Perugi, A. Chiesa di Sant’Andrea. In Il Centro Storico di Viterbo. Chiese, Conventi, Palazzi, Musei e Fontane; Anelli, V., Gimma, G., Eds.; BetaGamma: Viterbo, Italy, 2001; pp. 57–60. [Google Scholar]
  39. Galeotti, M. L’Illustrissima Città di Viterbo; Edizioni Studio Pubblicitario Viterbese: Viterbo, Italy, 2002; p. 635. [Google Scholar]
  40. Archive document: Fondo Fototeca Zeri, Busta 78. Pittura italiana sec. XIV. Siena, Lippo Memmi, Matteo Giovannetti, Maestro del Codice di San Giorgio, Barna, Naddo Ceccarelli, Maestro Houston, Fascicolo 3. Matteo Giovannetti e Viterbo sec. XIV. Coll. PI_0078/3/17 n. scheda n.6253; Foto Nr. 21386.
  41. Archive document: Archivio e Laboratorio Fotografico Istituto Autonomo Vittoriano e Palazzo Venezia. Relazione tecnica relativa al restauro degli affreschi esistenti nella Chiesa di S. Andrea a Pianoscarano in Viterbo. Restauratore R. Pizzinelli, Roma, 17 novembre 1982.
  42. Del Ciuco, S. Pianoscarano. Uomini, Cose ed Usanze di una Viterbo che Passa, 1st ed.; Ambrosini: Bolsena, Italy, 1987. [Google Scholar]
  43. Valtieri, S.; Bentivoglio, E. Viterbo nel Rinascimento; Ginevra Bentivoglio Editoria: Roma, Italy, 2012; p. 145. [Google Scholar]
  44. Melis, M.; Babbi, A.; Miccoli, M. Development of a UV to IR extension to the standard colorimetry, based on a seven band modified DSLR camera to better characterize surfaces, tissues and fabrics. In Proceedings of the SPIE Optical Metrology, Optics for Arts Architecture, and Archaeology III, Munich, Germany, 23–26 May 2011. [Google Scholar] [CrossRef]
  45. Melis, M.; Miccoli, M.; Quarta, D. Multispectral hypercolorimetry and automatic guided pigment identification: Some masterpieces case studies. In Proceedings of the Optics for Arts, Architecture, and Archaeology IV, Munich, Germany, 13–16 June 2013. [Google Scholar] [CrossRef]
  46. Laureti, S.; Colantonio, C.; Burrascano, P.; Melis, M.; Calabrò, G.; Malekmohammadi, H.; Sfarra, S.; Ricci, M.; Pelosi, C. Development of integrated innovative techniques for the examination of paintings: The case studies of The Resurrection of Christ attributed to Andrea Mantegna and the Crucifixion of Viterbo attributed to Michelangelo’s workshop. J. Cult. Herit. 2019, 40, 1–16. [Google Scholar] [CrossRef]
  47. Bonizzoni, L.; Caglio, S.; Galli, A.; Lanteri, L.; Pelosi, C. Materials and Technique: The First Look at Saturnino Gatti. Appl. Sci. 2023, 13, 6842. [Google Scholar] [CrossRef]
  48. Pelosi, C.; Fodaro, D.; Sforzini, L.; Falcucci, C.; Baraldi, P. The terracotta modelli of Palazzo Venezia in Rome: Investigation of the constituent materials for fundamental knowledge and to aid conservation decisions. Stud. Conserv. 2017, 62, 266–282. [Google Scholar] [CrossRef]
  49. Soares, I.; França de Sá, S.; Ferreira, J.L. A first approach into the characterisation of historical plastic objects by in situ diffuse reflection infrared Fourier transform (DRIFT) spectroscopy. Spectroch. Acta A 2020, 240, 118548. [Google Scholar] [CrossRef] [PubMed]
  50. Arrizabalaga, I.; Gómez-Laserna, O.; Carrero, J.A.; Bustamante, J.; Rodríguez, A.; Arana, G.; Madariaga, J.M. Diffuse reflectance FTIR database for the interpretation of the spectra obtained with a handheld device on built heritage materials. Anal. Methods 2015, 7, 1061–1070. [Google Scholar] [CrossRef]
  51. Kane, E.A. Document for the Fresco Technique of Matteo Giovanetti in Avignon. Stud. Ir. Q. Rev. 1975, 64, 368–378. [Google Scholar]
  52. Boust, C.; Wohlgelmuth, A. Database: Pigments under UV and IR Radiations, in Scientific Imaging for Cultural Heritage/Images Scientifiques Pour le Patrimoine. Available online: https://copa.hypotheses.org/552 (accessed on 5 December 2024).
  53. Lanteri, L.; Rusu, I.; Dura, I.; Pelosi, C. The potentiality of non-invasive diagnostics for the investigation of a Renaissance religious wall painting. Eur. J. Sci. Theol. 2024, 20, 133–146. [Google Scholar]
  54. Lanteri, L.; Pelosi, C. 2D and 3D ultraviolet fluorescence applications on cultural heritage paintings and objects through a low-cost approach for diagnostics and documentation. In Proceedings of the SPIE 11784, Optics for Arts, Architecture, and Archaeology VIII, Online, 21–26 June 2021; p. 1178417. [Google Scholar] [CrossRef]
  55. Cosentino, A. Practical notes on ultraviolet technical photography for art examination. Conserv. Património 2015, 21, 53–62. [Google Scholar] [CrossRef]
  56. Cosentino, A.; Stout, S. Photoshop and multispectral imaging for art documentation. e-Preserv. Sci. 2014, 11, 91–98. [Google Scholar]
  57. Darque-Ceretti, E.; Felder, E.; Aucouturier, M. Gilding of cultural heritage artefacts: An elaborated technology. Surf. Eng. 2013, 29, 146–152. [Google Scholar] [CrossRef]
  58. Brocchieri, J.; Scialla, E.; Manzone, A.; Graziano, G.O.; D’Onofrio, A.; Sabbarese, C. An analytical characterization of different gilding techniques on artworks from the Royal Palace (Caserta, Italy). J. Cult. Herit. 2022, 57, 213–225. [Google Scholar] [CrossRef]
  59. Harth, A. X-ray fluorescence (XRF) on painted heritage objects: A review using topic modeling. Herit. Sci. 2024, 12, 17. [Google Scholar] [CrossRef]
  60. Musílek, L.; Čechák, T.; Trojek, T. X-ray fluorescence analysis in the study of paintings—An overview. Radiat. Eff. Defects Solids 2024, 179, 1218–1232. [Google Scholar] [CrossRef]
  61. Berrie, B.H. Prussian Blue. In Artists’ Pigments. A Handbook of Their History and Characteristics, 1st ed.; West Fitzhugh, E., Ed.; National Gallery of Art: Washington, DC, USA, 1997; Volume 3, pp. 191–217. [Google Scholar]
  62. Gettens, R.J.; West Fitzhugh, E.; Feller, R.L. Calcium Carbonate Whites. In Artists’ Pigments. A Handbook of Their History and Characteristics, 1st ed.; Roy, A., Ed.; National Gallery of Art: Washington, DC, USA, 1993; Volume 2, pp. 203–226. [Google Scholar]
  63. Roy, A. Cobalt Blue. In Artists’ Pigments. A Handbook of Their History and Characteristics, 1st ed.; Berrie, B.H., Ed.; National Gallery of Art: Washington, DC, USA, 2007; Volume 4, pp. 151–177. [Google Scholar]
  64. Agresti, G.; Baraldi, P.; Pelosi, C.; Santamaria, U. Yellow pigments based on lead, tin, and antimony: Ancient recipes, synthesis, characterization, and hue choice in artworks. Col. Res. Appl. 2016, 41, 226–231. [Google Scholar] [CrossRef]
  65. EN 15757; Conservation of Cultural Property-Specifications for Temperature and Relative Humidity to Limit Climate-Induced Mechanical Damage in Organic Hygroscopic Materials. UNE-EN, AENOR: Madrid, Spain, 2010.
  66. So, R.T.; Blair, N.E.; Masterson, A.L. Carbonate mineral identification and quantification in sediment matrices using diffuse reflectance infrared Fourier transform spectroscopy. Environ. Chem. Lett. 2020, 18, 1725–1730. [Google Scholar] [CrossRef]
  67. Tatzber, M.; Stemmer, M.; Spiegel, H.; Katzlberger, C.; Haberhauer, G.; Gerzabek, M.H. An alternative method to measure carbonate in soils by FT-IR spectroscopy. Environ. Chem. Lett. 2007, 5, 9–12. [Google Scholar] [CrossRef]
  68. Petersen, K. Wall Paintings: Aspects of Deterioration and Restoration. In Conservation Science: Heritage Materials; May, E., Jones, M., Eds.; The Royal Society of Chemistry: Cambridge, UK, 2006; pp. 241–265. [Google Scholar]
  69. Horie, V. Materials for Conservation: Organic Consolidants, Adhesives and Coatings, 2nd ed.; Butterworth-Heinemann: Amsterdam, The Netherlands, 2010. [Google Scholar]
  70. Mora, P.; Mora, L.; Philippot, P. Conservation of Wall Paintings; Butterworths: London, UK, 1984. [Google Scholar]
  71. Artesani, A.; Di Turo, F.; Zucchelli, M.; Traviglia, A. Recent Advances in Protective Coatings for Cultural Heritage—An Overview. Coatings 2020, 10, 217. [Google Scholar] [CrossRef]
Heritage 08 00064 g001
Figure 1. Photograph of the porch’s wall, with the fragmentary wall painting on the left and the entrance of the church visible on the right side of the image. Photograph by Gaetano Alfano.
Figure 1. Photograph of the porch’s wall, with the fragmentary wall painting on the left and the entrance of the church visible on the right side of the image. Photograph by Gaetano Alfano.
Heritage 08 00064 g001
Heritage 08 00064 g002
Figure 2. The façade of St. Andrew’s church before 1899 (A) and after the 1945 restoration (B) [39].
Figure 2. The façade of St. Andrew’s church before 1899 (A) and after the 1945 restoration (B) [39].
Heritage 08 00064 g002
Heritage 08 00064 g003
Figure 3. The Madonna del Latte area. (A) An anonymous photograph dating back to the mid-20th century and obtained from Zeri’s archive [40]; (B) a photograph taken before the 1982 restoration, obtained from the archive and photographic laboratory of the Autonomous Institute Vittoriano e Palazzo Venezia [41].
Figure 3. The Madonna del Latte area. (A) An anonymous photograph dating back to the mid-20th century and obtained from Zeri’s archive [40]; (B) a photograph taken before the 1982 restoration, obtained from the archive and photographic laboratory of the Autonomous Institute Vittoriano e Palazzo Venezia [41].
Heritage 08 00064 g003
Heritage 08 00064 g004
Figure 4. A comparison of the conservation status of the painting in 1982 (A), 1987 (B), and 2012 (C), showing the progressive deterioration of the Madonna del Latte area. The image in (A) is taken from [42]; that shown in (B) is derived from [36] (p. 494), and the image displayed in (C) is from [43] (p. 145).
Figure 4. A comparison of the conservation status of the painting in 1982 (A), 1987 (B), and 2012 (C), showing the progressive deterioration of the Madonna del Latte area. The image in (A) is taken from [42]; that shown in (B) is derived from [36] (p. 494), and the image displayed in (C) is from [43] (p. 145).
Heritage 08 00064 g004
Heritage 08 00064 g005
Figure 5. Photograph of the wall painting with the thirty-two points where the onsite XRF measurements were performed.
Figure 5. Photograph of the wall painting with the thirty-two points where the onsite XRF measurements were performed.
Heritage 08 00064 g005
Heritage 08 00064 g006
Figure 6. Photograph of the wall painting with the ten sampling points selected for the laboratory analysis.
Figure 6. Photograph of the wall painting with the ten sampling points selected for the laboratory analysis.
Heritage 08 00064 g006
Heritage 08 00064 g007
Figure 7. Calibrated images of the Virgin scene obtained by the HMI system. (A) RGB image; (B) IRFC image; and (C) UVFC image. The color checker used for calibration is shown in the images.
Figure 7. Calibrated images of the Virgin scene obtained by the HMI system. (A) RGB image; (B) IRFC image; and (C) UVFC image. The color checker used for calibration is shown in the images.
Heritage 08 00064 g007
Heritage 08 00064 g008
Figure 8. Comparison between the blue color of the Virgin’s dress (blue circle and histogram) and that of the halo (pink circle and histogram). In the figure, the right part illustrates the results of the comparison between the two points selected in the RGB image of the painting (left side), in terms of both reflectance values (histograms) and color coordinates.
Figure 8. Comparison between the blue color of the Virgin’s dress (blue circle and histogram) and that of the halo (pink circle and histogram). In the figure, the right part illustrates the results of the comparison between the two points selected in the RGB image of the painting (left side), in terms of both reflectance values (histograms) and color coordinates.
Heritage 08 00064 g008
Heritage 08 00064 g009
Figure 9. UVF images. (A) A general image of the wall painting; (B) a detail of the Virgin. The circle in (B) highlights the angel’s halo, characterized by yellow fluorescence under UV radiation.
Figure 9. UVF images. (A) A general image of the wall painting; (B) a detail of the Virgin. The circle in (B) highlights the angel’s halo, characterized by yellow fluorescence under UV radiation.
Heritage 08 00064 g009
Heritage 08 00064 g010
Figure 10. The trend of the relative humidity values during the year of restoration work, from January 2021 to January 2022.
Figure 10. The trend of the relative humidity values during the year of restoration work, from January 2021 to January 2022.
Heritage 08 00064 g010
Heritage 08 00064 g011
Figure 11. The trend of the temperature values during the year of restoration work, from January 2021 to January 2022.
Figure 11. The trend of the temperature values during the year of restoration work, from January 2021 to January 2022.
Heritage 08 00064 g011
Heritage 08 00064 g012
Figure 12. (A) Detail of the angel’s halo at sampling point S7. (B) Cross-section under reflected light and (C) under ultraviolet radiation. Numbers 1, 2, 3, 4, and 5 indicate the layers. Image (A) was obtained by Gaetano Alfano.
Figure 12. (A) Detail of the angel’s halo at sampling point S7. (B) Cross-section under reflected light and (C) under ultraviolet radiation. Numbers 1, 2, 3, 4, and 5 indicate the layers. Image (A) was obtained by Gaetano Alfano.
Heritage 08 00064 g012
Heritage 08 00064 g013
Figure 13. (A) Detail of the Virgin’s face and halo at sampling point S8. (B) Cross-section under reflected light and (C) under ultraviolet radiation. Numbers 1, 2, 3, 4, 5, 6, and 7 indicate the different layers. Image (A) was obtained by Gaetano Alfano.
Figure 13. (A) Detail of the Virgin’s face and halo at sampling point S8. (B) Cross-section under reflected light and (C) under ultraviolet radiation. Numbers 1, 2, 3, 4, 5, 6, and 7 indicate the different layers. Image (A) was obtained by Gaetano Alfano.
Heritage 08 00064 g013
Heritage 08 00064 g014
Figure 14. (A) Detail of the Virgin’s face and halo at sampling point S9. (B) Cross-section under reflected light and (C) under ultraviolet radiation. Numbers 1, 2, 3, 4, 5, and 6 indicate the different layers. Image (A) was obtained by Gaetano Alfano.
Figure 14. (A) Detail of the Virgin’s face and halo at sampling point S9. (B) Cross-section under reflected light and (C) under ultraviolet radiation. Numbers 1, 2, 3, 4, 5, and 6 indicate the different layers. Image (A) was obtained by Gaetano Alfano.
Heritage 08 00064 g014
Heritage 08 00064 g015
Figure 15. (A) Detail of the Virgin’s scene at sampling point S10, taken from the background. (B) Cross-section under reflected light and (C) under ultraviolet radiation. Numbers 1, 2, 3, 4, 5, and 6 indicate the different layers.
Figure 15. (A) Detail of the Virgin’s scene at sampling point S10, taken from the background. (B) Cross-section under reflected light and (C) under ultraviolet radiation. Numbers 1, 2, 3, 4, 5, and 6 indicate the different layers.
Heritage 08 00064 g015
Table 1. Counts per second (cps) obtained for each element detected by XRF spectroscopy.
Table 1. Counts per second (cps) obtained for each element detected by XRF spectroscopy.
Point Number and ColorCaFeCoCuAsRbSrZrSnAuHgPb
1-Black19627-77-16127-----
2-Light Blue10037-5933-212320---703
3-Blue76296-7137--15----61
4-Black149277-6219--22----31
5-Green–Blue120110273807-------783
6-Yellow14972-1069--26----1795
7-Light Blue9025-1165--43----2541
8-Light Green137114-1588--297247---542
9-Black10890--4493011249---374
10-Yellow133166--348-12340---368
11-Black13638--786-19738---81
12-Black25958-36-3519170---15
13-Light Green9563-608-2813039---785
14-Yellow223192-32-37123----13
15-Yellow6724-2409--23-70--1840
16-Yellow13446-305-------1351
17-Yellow89220--9231570----905
18-Yellow194326---2916492----
19-Red10777----37---252967
20-Red13346--------344573
21-Red1601710---3413156---24
22-Red107803---277577--3666
23-Red116609---2011162---83
24-Flesh Hue23033---2015327----
25-Flesh Hue23559---3015047----
26-Green159166---37135-----
27-Black11048-173-3633--113-83
28-Yellow7514-203-245817-195-45
29-Yellow6612-76-2167--178-26
30-Yellow132132-1522--17--288-35
31-Yellow131407-85-3542--80-391
32-Brown11023-672011458---134936
Table 2. Summary of FTIR results.
Table 2. Summary of FTIR results.
SampleFTIR Main Signals (cm−1)Identified Compounds
S1, blue sample from the background, upper zone of the Virgin’s scene, original layer(1) 3408, 2240, 2120, 1120, 670, 603, 456; (2) 2552, 2499, 1881, 1472, 1420, 1041, 954, 829, 770; (3) 1728; (4) 1643, 1384, 1324, 829(1) gypsum; (2) azurite; (3) organic carbonyl; (4) copper oxalates (moolite)
S2, black in the background, left side of the Virgin’s scene(1) 3523, 3403, 1119, 673, 603, 467; (2) 2511, 1795, 1431, 875, 713; (3) 1725, 1046; (4) 1640, 1384, 1324, 780(1) gypsum; (2) calcium carbonate; (3) organics; (4) oxalates
S3, brown layer from the scene with the praying person, lower side(1) 3540, 3403, 2227, 1142, 672, 603; (2) 2869, 2512, 1794, 1443, 874, 713; (3) 1644, 1384, 1324, 823(1) gypsum; (2) calcium carbonate; (3) oxalates
S4, retouching area(1) 3540, 3403, 1145, 1119, 671, 602; (2) 2877, 2512, 1795, 1446, 875, 712; (3) 1738, 1036; (4) 1626, 1384, 1324, 781(1) gypsum; (2) calcium carbonate; (3) organics; (4) oxalates
S5, fragment of the halo, to the left of the Virgin’s face(1) 3548, 3404, 2232, 2113, 1142, 1121, 671, 603, 468; (2) 2510, 1794, 1432, 875; (3) 1728, 1043; (4) 1649, 1384, 1325, 779(1) gypsum; (2) calcium carbonate; (3) organics; (4) oxalates
S6, white surface layer, sampled from the left side corresponding to grouting(1) 3424, 1160, 606; (2) 2987, 2873, 2512, 1795, 1443, 875, 713; (3) 1732, 1084, 1043; (4) 1632, 1385, 824(1) gypsum; (2) calcium carbonate (main component); (3) organics; (4) oxalates
S7, micro-fragment from the halo of the angel on the left side of the Virgin’s throne(1) 3435, 3407, 2253, 1145, 1122, 673, 604, 461; (2) 2922, 2852, 1725, 1236; (3) 3236, 1654, 1552, 1464; (4) 1419, 957, 836, 780; (5) 1385, 1324; (6) 876(1) gypsum; (2) organics, probably lipidic compounds; (3) organics (probably proteins); (4) azurite; (5) oxalates; (6) calcium carbonate (traces);
Table 3. Comparison between pigments found in the painting of the Madonna del latte in Viterbo and those found in the consistory hall in Avignon.
Table 3. Comparison between pigments found in the painting of the Madonna del latte in Viterbo and those found in the consistory hall in Avignon.
ColorMadonna del Latte, St. Andrew’s Church, ViterboConsistory Hall, Palace of the Popes, Avignon (1347)Execution Technique
BlackOrganicOrganicFresco painting
YellowOchre, orpiment, lead/tin yellow Ochre, orpiment, massicot (lead oxide)Fresco painting + secco painting (orpiment)
RedHematite, red earth, vermilion/cinnabarHematite, red earth, minium, shellac, vermilion/cinnabarFresco painting + secco painting (vermilion/cinnabar, minium and shellac)
GreenGreen earth, malachiteMalachite (called green of Alemannia), verdigrisSecco painting + fresco painting (green earth)
WhiteCalcium carbonate (the so-called San Giovanni Bianco), lead whiteCalcium carbonate (the so-called San Giovanni Bianco), lead white (called cerussa)Fresco painting (calcium carbonate white) + secco painting (lead white)
BlueAzuriteAzuriteSecco painting
Metal leafGold Gold, tinApplication with adhesive
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Tovazzi, V.; Pelosi, C.; Falcucci, C.; Gittins, M.; Lanteri, L. Diagnostics and Analytical Campaign as Support for the Restoration Activity of a 14th-Century Mural Painting Representing the Virgo Lactans. Heritage 2025, 8, 64. https://doi.org/10.3390/heritage8020064

AMA Style

Tovazzi V, Pelosi C, Falcucci C, Gittins M, Lanteri L. Diagnostics and Analytical Campaign as Support for the Restoration Activity of a 14th-Century Mural Painting Representing the Virgo Lactans. Heritage. 2025; 8(2):64. https://doi.org/10.3390/heritage8020064

Chicago/Turabian Style

Tovazzi, Valery, Claudia Pelosi, Claudio Falcucci, Mark Gittins, and Luca Lanteri. 2025. "Diagnostics and Analytical Campaign as Support for the Restoration Activity of a 14th-Century Mural Painting Representing the Virgo Lactans" Heritage 8, no. 2: 64. https://doi.org/10.3390/heritage8020064

APA Style

Tovazzi, V., Pelosi, C., Falcucci, C., Gittins, M., & Lanteri, L. (2025). Diagnostics and Analytical Campaign as Support for the Restoration Activity of a 14th-Century Mural Painting Representing the Virgo Lactans. Heritage, 8(2), 64. https://doi.org/10.3390/heritage8020064

Article Metrics

Back to TopTop