RT Journal Article
SR 00
A1 Bugini, Roberto
A1 Corti, Cristina
A1 Folli, Luisa
A1 Rampazzi, Laura
T1 Roman wall paintings: characterisation of plaster coats made of clay mud
JF Heritage
YR 2021
FD 2021-05-20
VO 4
SP 889
OP 905
K1 Clay mud
K1 plaster coat
K1 Roman plaster
K1 wall paintings
K1 Egyptian blue
K1 FTIR
K1 SEM-EDX
K1 XRD
K1 reflectance infrared spectroscopy
K1 thin sections
AB This paper reports on the mineralogical characterisation of samples of wall paintings from various Roman sites in Lombardy (Italy), revealing recurrent types of stratigraphy. One of the stratigraphic samples analysed was found to be a particular kind of plaster: a three-coat work featuring two coats made of clay mud, found in the site of Santa Maria alla Porta (area of the Imperial Palace of Milan—first century CE). The fragments were analysed using optical microscopy on thin sections, X-ray diffraction, scanning electron microscopy with an energy-dispersive spectrometer and infrared spectroscopy, also in non-invasive external reflection mode (7500–375 cm−1). The most interesting feature found was the finish coat made of clay mud (illite, chlorite, kaolinite and fine quartz) with a few coarse clasts and linear cavities. This clay coat was the first example ever detected in Roman Lombardy and was used in combination with a thin painted coat made of clay mud with coarse clasts together with a blue pigment (Egyptian blue) and a render coat made of lime associated with lithic clasts (sand). Our findings brought to light a particular construction technique, since in the historical sources clay is only recommended for daubing on reeds and as a render coat.
PB MDPI
SN 2571-9408
LK http://openarchive.icomos.org/id/eprint/2532/
UL https://www.mdpi.com/journal/heritage