Recreation of Purple: A Study of Color-Shifted Dyes Available for Fayum Funerary Portraits
Funerary portraits from Graeco Roman Egypt indicated the socioeconomic status of the deceased. Color is one major consideration in interpreting such paintings. In “32.6 The Bearded Man” a purple clavus is observed indicating a high socioeconomic standing. Nanoscale chemical characterization was conducted on small particle of the clavus to better understand the provenience of the portrait. Energy dispersive spectroscopy and atom probe tomography indicated that the pigment used on the clavus was not the traditional Tyrian purple made from Murex, a large sea snail. Rather, it was determined to be from a different organic that was shifted with alkali and/or metal salts to make the purple pigment.
Further research narrowed down the list of possible organic compounds and metal salts available to the Fayum region at the time. Based on the research of available compounds a matrix of samples was generated. The three types of organics analyzed were madder root, kermes, and alkanet root. Each organic was mixed with varying concentrations of lead sulfate, sodium dichromate, iron sulfate, and potassium hydroxide. Samples were characterized by fluorescence and absorbance spectroscopy. Then a final set of select dyes were made into lake pigments and suspended in encaustic wax, the media used in The Bearded Man. The encaustic samples were characterized again using spectroscopy.
Stroud, John Paul; Laurino, Alaggio; Cannon, Brittany; and Herren, Benjamin, "Recreation of Purple: A Study of Color-Shifted Dyes Available for Fayum Funerary Portraits" (2017). 2017 Undergraduate Research and Scholarship Conference.