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 (CO2, SO2 and NOx) 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 CO2, SO2 and NOx 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. Copyright © 2014 John Wiley & Sons, Ltd.