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Investigating the Coffins

These are some of the imaging and analytical techniques we use to reveal the methods and materials of ancient Egyptian craftsmen. Through these we discover the skill and ingenuity of the carpenters and artists, and the practical problems they faced.

The process of investigation begins with detailed examination, often using a stereomicroscope with magnification up to about ×60, and a raking light to show up surface relief.

Features of interest are recorded photographically using ultraviolet light to help locate organic coatings such as varnishes and clarify areas of restoration, and infrared radiation to reveal carbon-based pigments below the surface (e.g., in underdrawings). Visible-light induced luminescence (VIL) is a photographic technique that captures the infrared fluorescence of the pigment Egyptian blue.

Fibre optic reflectance spectroscopy (FORS) and X-ray fluorescence spectrometry (XRF) allow identification of pigments without the need to remove samples.

Further information can be obtained by taking tiny samples and analysing them with polarised light microscopy (PLM), X-ray powder diffraction (XRD) and Raman spectroscopy. The layer structure of the decoration is visible on cross-section samples viewed under high magnification. Analyzing these samples in a scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDX) locates the various inorganic pigments.

Original varnishes and resins on the coffins are identified from tiny samples using Fourier transform infrared spectroscopy (FTIR), which reveals the general character of the material, allowing us, for example, to differentiate tree resins from sugary gums. This is followed by gas chromatography–mass spectrometry (GC-MS), which can identify all the individual molecular components of the material so that its botanical origin can be determined.

X-radiography and computed tomography (CT) scanning look beneath the surfaces of coffins to reveal the methods of construction, and scanning electron microscopy is used to identify all the different woods employed.