When you envisage Greek statues and friezes, you probably picture pure white marble sculptures, pockmarked with age – that is, after all, how they appear today. But that was not how they appeared to the ancient Greeks who made them, and carefully carved them with detailed textures and painted them in refined colours. In this month’s ‘Science Notes’, we delve into new research examining whether recent digital imaging, infrared luminescence, and X-ray fluorescence techniques could help find evidence for these textures and colours on the sculptures that once adorned the Parthenon in Athens, some of which are now housed in the British Museum.
After centuries of weathering, transportation over hundreds of miles, use of them as casts to make plaster copies, and cleaning and conservation, most of the original paint on the Parthenon Sculptures has long faded – but that does not mean that traces cannot be discerned using certain techniques. Visible-induced luminescence (VIL) is a non-invasive imaging technique that is able to create images that show the presence of certain pigments, including Egyptian blue (a colour made from a mixture of silica, lime, copper, and an alkali, that originated in ancient Egypt but was frequently used in ancient Greece). VIL uses green or red light, which is absorbed by Egyptian blue and re-emitted as infrared radiation. While infrared radiation is invisible to the naked eye, a digital camera can easily detect it, and in the resulting images pigments will appear bright white against a grey-black background. VIL images are important because they do not only tell that the pigment is present, but also reveal its distribution, providing crucial information on patterns, designs, and painting techniques. Fibre-optic reflectance spectroscopy (FORS) and X-ray fluorescence spectroscopy (XRF) can also be used to determine the possible composition of pigments in situ, while microsamples of the identified pigments can be examined using optical and scanning electron microscopy to determine their composition.
Using these techniques, researchers from the Art Institute of Chicago, the British Museum, and King’s College London examined the East Pediment (EP), the West Pediment (WP), and the East Frieze (EF). First, they documented any examples of carving marks, finding that they could often still be seen on the inside and undercuts of drapery folds. This showed that the carvers, rather than gradually transforming the whole block of stone into its final form, worked in sections, bringing each portion down to the final form before starting on the next. They found that the carvers seem to have altered their techniques based on the subject matter, too, in order to achieve various textures to represent different materials in the figures’ garments.
The team next turned to examining the pigments used. VIL was able to identify Egyptian blue – combined with two different types of white pigments, gypsum and probably bone white – on 11 pedimental sculptures and one figure from the frieze. This showed that the blue had been used to colour water on the EP, skin on a snake-like creature that might represent Kekrops (the mythical king of Athens) on the WP, as well as on some of the background spaces. Most of the Egyptian blue, however, was found on textiles, particularly on those depicting a woven design. On one figure, the researchers were pleasantly surprised to find complex ‘woven’ figurative designs, in which figures appear and disappear within the complex folds of the drapery.
A bright purple pigment was found on a piece of cloth on the EP. FORS and XRF analysis of this showed that it did not contain bromine, which rules it out as being an example of a ‘true’ or Tyrian purple extracted from sea snails (see ‘Science Notes’ in CA 371). Instead, it seems to have been made with anthraquinones, a naturally occurring phenolic compound found in various plants, fungi, lichens, and insects. Investigations into its full composition are still ongoing.
Notably, textures and colours were found on the back of the sculptures as well, in locations that would have been invisible on the building, suggesting that this was not the primary concern when creating them. There must have been another reason that they were made ‘in the round’: whether this was to impress important visitors while they were being crafted, to please the gods to which they were dedicated, or for other reasons is up for debate.
Writing in a paper recently published in Antiquity (https://doi.org/10.15184/aqy.2023.130), the researchers commented: ‘The pediment artists were sympathetic to the final intended polychrome sculpture, providing surfaces that evoked textures similar to those of the subjects represented. They used innovative modelling techniques to achieve extraordinary sculptural effects and provide support for the complex decorative and figurative designs that would subsequently be painted on them.’ It shows that great care with the details went into their creation.
A video illustrating the results of the research project can be found here: http://www.youtube.com/watch?v=d8jEmTR0mMw.
Text: Kathryn Krakowka / Image: Giovanni Verri © Trustees of the British Museum (inv. no. 1816,0610.97)