The present study investigates and compares the vermilion red color change
phenomenon in an oil painting executed on wood from the 18th century stored
at the Archaeological Museum Store of Manial Palace Museum, Cairo and a
mural painting executed using Tempera from the Greco-Roman Period in a
destroyed archeological house next to Medinet Madi Temple, (35kms far from
Fayoum city). The vermillion red color may change to dark red, brown, or
grayish-white due to the exposure to the environmental conditions and
pollutants, the common role of both light and chlorine as the main factors of red
discoloration, some impurities in color components, as well as the dissolved
salts and organic media used in painting. The blackness of the color was
detected after doing an analytical study to identify the damaged products of
the vermillion red using different methods of analysis (i.e. microscopy, X-ray
diffraction, Energy Dispersive X- rays and Infrared). The change to gray color
in oil paintings due to the presence of the prokovite was associated with
cinnabar. In the mural painting, it resulted from the conversion to black
hypercinnabar, not to the resin.