In situ analysis with portable Raman and ED‐XRF spectrometers for the diagnosis of the formation of efflorescence on walls and wall paintings of the Insula IX 3 (Pompeii, Italy)

Abstract

This work presents the results of field Raman analyses, assisted by a hand-held energy dispersive X-ray fluorescence spectrometer, for the experimental determination of efflorescence from walls and wall paintings of two Pompeian houses, one with many luxurious decorative elements (House of Marcus Lucretius, Regio IX, Insula 3, House 5/24) and a more modest building (Regio IX, Insula 3, House 1-2). Both exposed and protected rooms were measured in different year seasons, spring (May 2010) and summer (September 2011 and 2012) and considering different orientations. Chemical attacks of acid gases (CO 2 , SO 2 and NO x ) on the original compounds of the mortars, biominerals formed by the biological colonizations as well as direct rain-wash of the newly formed salts can be considered the three most serious problems of the archaeological remains from Insula IX 3 of Pompeii. Also, infiltration waters from the ground contribute to such decay. The walls and wall paintings exposed to the rain-wash are the worst preserved, probably as a result of a continuous cycle of CO 2 , SO 2 and NO x acid attack to the original carbonate materials, involving loss of plaster. This severe decay was not observed in the rooms covered by roofs although those walls affected by infiltration waters from the ground showed decaying because of the action of the efflorescence on the carbonate materials acting as the binder of the mural painting remains in the houses of Pompeii.

Raman spectroscopy of minerals and mineral pigments in archaeometry

“…In the last period, 2014/2015, we can cite further relevant studies on wall paintings of two Greek Byzantine Churches from Kastoria, northern Greece (Iordanidis et al); pigments in the wall paintings at Jokhang Monastery in Lhasa, Tibet, China (Li et al); a wall painting attributed to Ambrogio Lorenzetti in the St Augustine Church in Siena, Italy (Damiani et al); the pigments in dome wall paintings by Correggio in Parma cathedral (Bersani et al); 17th century mural paintings, Dominican Convent of Nossa Senhora da Saudacao, Montemor, Portugal (Gil et al); medieval Nubia wall paintings from Saras, Old Dongola and Banganarti archaeological sites (Syta et al); wall paintings in Pompeii (Madariaga et al); wall paintings from Qasr El‐Ghuieta Temple, Kharga Oasis, Egypt (Mahmoud); the wall paintings from the Baños de Doña Maria de Padilla in the Alcazar of Seville (Perez‐Rodriguez et al); binder compositions in Pompeian wall paintings from Insula Occidentalis (Gelzo et al); gilded plasterwork in the Hall of the Kings in the Alhambra complex, Granada, Spain (de la Torre‐López et al); wall paintings in the San Francisco Church, Santiago, Chile (Araya et al); the wall paintings in the Churches of Panagia and Theotokos built in the settlements of Patsos and Meronas at Amari Rethymno, Crete (Cheilakou et al); wall painting fragments from Roman villas of the Sabina area, Rome (Paladini et al); the wall paintings from the Hellenistic hypogeum of Apaforte‐Licata, Agrigento, Sicily (Aquilia et al); wall paintings in the Villa of the Papyri in Herculaneum (Amadori et al); and decorative fragments from the hypocaustum in the Roman villa of El Ruedo, Almedinilla, southern Spain (Mateos et al).…”

A multi-technique approach, based on mobile/portable laser instruments, for the in situ pigment characterization of stone sculptures on the island of Crete dating from Venetian and Ottoman period

“…Collecting microsamples is often an alternative for bypassing the above limitations, but current trends, concerning protection and preservation of cultural heritage objects, impose non-sampling policies or strict controls in performing sampling for further analysis in the laboratory. Obviously the option to use mobile analytical equipment, which can be operated on site, emerges as an important prospect [1][2][3][4][5].…”

“…In brief, Raman microspectroscopy is nowadays a broadly established technique for materials analysis and has been shown to be a powerful analytical tool in the context of art conservation and archaeological science, with significant results concerning pigment identification [4][5][6][7]. It offers high sensitivity and specificity enabling analysis of a wide variety of inorganic and organic materials, often directly on the object under study, noninvasively, in a short time and with very high spatial resolution.…”

Applications of Raman spectroscopy in art and archaeology

“…Efflorescence from walls and wall paintings of two Pompeian houses were analysed in the field by Madariaga et al . by using a portable Raman spectrometer (785 nm), assisted with a handheld ED‐XRF spectrometer.…”