Methodology

Raking light is a technique of shining light almost parallel to an object’s surface in order to reveal texture and topography. Specular techniques measure the ways in which light reflects from a surface, which may help determine alterations and materials used. Magnification is used to enhance minute details revealing the artist’s technique, the work’s condition, and the materiality of an object.

This non-invasive imaging technique uses X-rays to see through an object and expose features not visible to the naked eye, such as contrasts in the materials used, restorations, and the overall condition of an object.

This X-ray image shows the differences in material densities, revealing different pigments, brush strokes, and that the panel consists of 18 pieces, some of which do not appear to be original.

Ultraviolet-Induced Visible Fluorescence (UVF)

This is a non-invasive imaging technique that helps to differentiate materials used on the surface of an object, such as pigments, coatings and adhesives, based on their characteristic visible response to ultraviolet radiation.

This portrait of a woman was photographed with ultraviolet radiation, revealing a bright pink fluorescence diagnostic of the pigment madder lake (above left).

Reflected Infrared (IR) and False Color Infrared (FCIR)

Reflected infrared light is a non-invasive imaging technique which allows one to “see” below paint layers, revealing underdrawings and corrections. It can help reveal the ancient artist’s creative process.

The false color infrared image, seen here, displays magenta and yellow/green colored details diagnostic of the pigments indigo and red ochre, respectively (above right).

Visible-Induced Infrared Luminescence (VIL)

This non-invasive imaging technique helps characterize a unique group of pigments by their luminescent response (captured in the infrared when exposed to visible light).

This image reveals the use of the pigment Egyptian blue. Its bright luminescence indicates that it was used to paint the garment and jewelry, and was mixed with white for the highlights in the hair and eyes

Uses non-invasive and invasive (requiring small samples) analytical techniques such as X-ray fluorescence, gas chromatography, fiber optics reflectance spectroscopy, polarized light microscopy, and scanning electron microscopy, among others. These analytical methods provide valuable material identification, expanding our knowledge of ancient painting materials and techniques.

Macro-X-Ray Fluorescence

Macro-X-ray fluorescence mapping of Mummy Portrait of a Woman (81.AP.42) was performed by the Getty Conservation Institute. This technique maps the distributions and relative concentrations of elements on the surface of a painting. This method helps with characterizing the pigments used to paint the portrait and, in some instances, how they may have been used.

Gas Chromatography/Mass Spectroscopy (GC/MS)

Getty Conservation Institute assistant scientist, Joy Mazurek, is seen here sampling the paint from Mummy Portrait of a Woman (79.AP.129). By analyzing tiny samples using Gas Chromatography/Mass Spectrometry (GCMS), a technique for identifying unknown organic substances, the binding media used to paint this tempera portrait was confirmed to be animal glue.

Fiber Optics Reflectance Spectroscopy (FORS)

A non-invasive method for identifying the inorganic and organic materials used to create a mummy portrait (such as colorants, media, and coatings). Here, Sara Levin, former Getty graduate intern (2014–15), is analyzing the white pigment used to paint the tunic on the Mummy Shroud of a Boy (75.AP.87).

Visible-Induced Visible Luminescence (VIVL)

Technical imaging is an important non-invasive technique to better characterize the materials, methods, and condition of mummy portraits. Senior imaging specialist from the Los Angeles County Museum of Art, Yosi Pozeilov, is shown capturing visible-induced visible luminescence (VIVL) images to detect painted details not visible to the naked eye and understand how the artist created the Mummy Shroud of a Boy (75.AP.87).

Polarized Light Microscopy (PLM)

In this image, traces of textile fibers can be clearly identified using 40x magnification. These fibers, taken from Portrait of Man (73.AP.94) have the characteristic features associated with common flax, better known as linen. Linen wrappings were used to envelope mummified remains and secure a portrait panel in place.

Tool marks, panel shape and preparation, inscriptions, dealer marks, and the addition of decorative details (impasto, stucco, gilding, etc.) are features that provide another level of understanding ancient panel painting technology, collection history (provenance), and ways to identify workshops and artist’s hands.

The production of mummy portraits can be observed through details remaining on the surface.

On Mummy Portrait of a Man (71.AP.72), not only are the brush and tool marks visible, but the modifications of the panel for insertion into its mummy can also be seen. The 2mm-thick linden wood panel has been “nibbled” at the top and “scored” on the side, evidence of reshaping this panel so it conforms to the mummy bundle.

The reverse of funerary portraits, often never seen, can provide valuable information about the materials used to create Romano-Egyptian mummies. Traces of linen bandages, fabrics, and resins used to wrap the mummy and secure the portrait over the head still exist on the back of a Mummy Portrait of a Bearded Man (73.AP.94)

Still attached to the front surface of Portrait of a Man (74.AP.11) is a clump of woven textile adhered with resin to the surface. These are the remains of the mummy wrappings that attached the panel to its mummy.

This wonderful detail of the pendant, gold chains and gem stones worn by “Isidora,” Mummy Portrait of a Woman (81.AP.42) not only reveals the artists’ technique, materials (such as gold leaf over yellow ochre details) and tool marks common to encaustic paintings, it also emphasizes the social status of Isidora as “elite.” We know the portrait represents “Isidora” as her name is written in Greek on the outside of the remains of her shroud.

This helps reveal how and when portraits were restored or conserved, informing us about former conditions, original versus restored sections, and possibly provenance information.