Digital Sculpture Project: Augustus of Prima Porta
Augustus of Prima: Report on the Polychromy (2011)
Paolo Liverani, University of Florence
Figure 1: Cast of the Augustus of Prima Porta with restored polychromy. Vatican Museums. Photograph: Bernard Frischer.
The discovery of the Augustus of Prima Porta on April 20, 1863 caused an immediate sensation, because of both the quality of the piece and its excellent state of preservation (Liverani 1989). Although it had a few breaks, the statue was essentially complete and showed clear traces of color. These were surveyed with care by the first scholars to work on it--Luigi Grifi, Ulrich Köhler, Otto Jahn, and, a little later, Walther Amelung in his catalogue of the Vatican Museums.
In the following years, there was some loss of color as result of natural fading with the passage of time and also because of plaster casts executed in the 19C without protection or preliminary consolidation of the original surface. Notwithstanding these problems, the colors are in large part preserved exactly where the nineteenth-century archaeologists indicated they should be: covered over by the lime incrustations that luckily were not removed by the cleaning undertaken by Tenerani after the discovery.
In 2002, the Stone Restoration Lab of the Vatican Museums started a careful and painstaking cleaning which has brought back to light many traces of color that are no longer visible. A series of tests of the statue was also initiated by the Department of Scientific Research of the Museums, under the direction of Prof. Ulderico Santamaria. Ultraviolet light photographs have revealed more of the color than can be detected by the naked eye. Under ultraviolet light, the areas with color emit light at different frequencies from that emitted by the marble, the lime incrustations, or by the plaster, which gives off a bright blue.
To understand the nature and the composition of the pigments, they were subjected to an examination by x-ray fluorescence. Then a series of samples were subjected to a morphological test with a stereomicroscope. A polarising microscope was used for a minerologic-petrographic study. Finally, scanning electron microscopy (SEM-EDS) was used for an infrared spectroscopic analysis with x-fluorescence (FTIR).
The results of these investigations showed that colors were applied on the clothing, on details of the armor, on the hair and on details of the eyes but not on the skin or on the ground of the armor. Only on the internal part of the left arm, just above the cloak, can we find a trace of red, which, however, must be probably interpreted as a smudge of the brush which extended the color of the cloak to a point normally hidden from view. Thus, it seems that the skin and the ground of the armor maintain the color and transparency of the Parian marble from which the statue is carved.
The palette used for the statue had few colors-perhaps five or six-which were generally used without mixing.
- Blue was used for the cloak of the personification of the Sky, for metallic items such as the standard returned by the Parthian soldier, the wheel of the Chariot of the Sun, the helmet of the god Mars who receives the standards and for the lappets which hang down from the bottom of his cuirass. Blue is also painted on some details of the fringe of Augustus' armor and also for the bracae or pants of the Parthian soldier.
- Bright red is used for the tunic and the cloak of Augustus, for the cloak, tunic, and various details of the armor of the god Mars on Augustus' cuirass and for some tones of the Sky.
- A red which is a bit less intense ("Indian Red") was used for the mantle of the god Mars, for the doe of Artemis and on the seat of the personification of people on the right side of Augustus' breastplate.
- A Siena brown was used for the dog of the personification of people on the right side of Augustus' armor and probably for the hair of Augustus and of the Cupid figure at his side.
- Yellow was used on the fringe of Augustus' cuirass.
From the point of view of the composition, the blue is the so-called "Alexandrian blue", a mineral of copper known as "cuprorivaite" that was normally used in antiquity. The red was extracted from oxides of lead and from such ferrous oxides as ochre, cinnabar, and vermilion. The yellow was obtained from lead oxides. The brown is composed of a mixture of ferrous and lead oxides. The bright red color is innovative. It is a lac-dye, and thus an organic coloring extracted from wild madder. The effect of this kind of color must have been quite fine and transparent.
The analyses have also established that the paint of the statue underwent at least one restoration in antiquity. Apart from minor indications, we have a pair of very clear examples. On the mantle of the god Mars in the center of his cuirass, two strata of colors are superimposed. The more ancient is much more refined. It has an orange tint and is made of red ochre, vermilion and cinnabar. The later stratum is red ochre composed of ferrous and lead oxides. The lead oxides are present in the later level in much greater abundance than in the earlier one.
The second example presents an even greater variation. On the fringe of the lappets a yellow color has been superimposed on the blue known as "Alexandrian blue." In this case, too, the original color in the older layer is of better quality. This was replaced by a color with a lead oxide base in the later layer. It appears, generally speaking, that the later colors have a higher lead oxide content that is usually less stable and thus is of inferior quality. In this case, then, there is a change of color much more decisive than that seen on the mantle of Mars. Initially, the blue was used to indicate the fringe of the bronze edge. But-once the original color had in large part faded-it seems that a color that was less expensive and easier to apply was preferred. Moreover, yellow was apparently used to suggest gold (a unique example of this on the statue) with the goal of making the impact richer and less sober. This detail makes one think of the high or later imperial period when the use of gold in polychromy of statues was rather widespread.
A restoration of the colors in antiquity is highly probable given that ancient restorations of the right leg and right arm have been noted. The right shoulder was carved as a separate attachment and then repaired at a later date in a very crude way. Finally the identification of protein substances are probably traces of casein that is of a binder derived from milk.
On the basis of these tests, a complete reconstruction of the colors was prepared on a plaster cast (figure 1). The surviving traces are sufficient to permit the colors to be reconstructed over most of the surface. The missing parts were supplemented in a hypothetical manner based on the logic of the use of colors on the statue and on comparisons with roughly contemporary portraits.
Bibliography
Liverani, P. 2004. "Augusto di Prima Porta," in I colori del bianco. Policromia nella scultura antica, De Luca Editori, Rome: 235-242.
Santamaria, U., Morresi, F. 2005. "Le indagini scientifiche per lo studio della cromia dell'Augusto di Prima Porta, in I colori del Bianco: policromia nella scultura antica, De Luca Editori, Rome: 243-248.
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