The Fayum mummy portraits pertain to a definitive art style from the Coptic period (that also included the Roman occupation of Egypt, from 1st to 3rd century AD), known for their realistic portrayals of the deceased. In fact, their essence of realism and poignancy has perplexed many a historian, and as such these 2,000 years old ancient artworks are sometimes considered as precursors to the scope of Western portraiture. And this time around, a group of researchers from the Northwestern University has dabbled in hi-tech wizardry to find answers behind the degree of expertise and materials required to concoct these fascinating portraits.
To that end, the scientists have found much about the underlying techniques that were used for around 15 specimens of mummy portraits. The ‘detective work’ entailed the identification of the pigments used for coloring, the correct order of applying the paint layers, the regional style of brushstrokes that offered subtle differences in portraits, and finally the source of the materials used for such ritzy artworks (as they were usually patronized by the affluent upper class). Marc Walton, a senior scientist at the Northwestern University-Art Institute of Chicago Center for Scientific Studies in the Arts (NU-ACCESS), and the leader of the study, said –
Our materials analysis provides a fresh and rich archaeological context for the Tebtunis portraits, reflecting the international perspective of these ancient Egyptians. For example, we found that the iron-earth pigments most likely came from Keos in Greece, the red lead from Spain and the wood substrate on which the portraits are painted came from central Europe. We also know the painters used Egyptian blue in an unusual way to broaden their spectrum of hues.
As for the use of (non-invasive) analytical technologies for detecting so many varied parameters, the researchers used both optics and signal processing. For example, an array of computation cameras were used for capturing these portraits under different levels/angles of illumination, thus allowing more insight into the internal juxtaposition of shapes and hues. This was complemented by photometric stereo, an imaging algorithm that was instrumental in rather ‘calculating’ the number of brush and tool strokes. This software was also helpful in determining the layered composition of the portraits, which hinted at the order of pigments used for the painted outcome.
The researchers were also able to ‘gauge’ the color composition of the mummy portraits by utilizing visible hyperspectral imaging data. Comparative assessments were made with reflectance level of pigments used in the portraits painting during the Roman era and salvaged using signal processing algorithms. The compiled info was further used for collecting micro-samples of paint from these mummy portraits for real-time (precise) identification of the ancient pigments.
The study was originally conducted as the AAAS presentation titled ‘Romano-Egyptian Mummy Portraits from Tebtunis, Egypt’.