Reflectance Spectroscopy

Reflectance spectroscopy is a non-invasive analytical technique widely used in art history, conservation, and archaeology to investigate the optical properties of materials. By measuring the fraction of light reflected from a surface across a defined range of wavelengths—typically from the ultraviolet through the visible and into the near-infrared—it provides characteristic spectral signatures that can be linked to specific pigments, dyes, and surface treatments.

In the study of artworks, reflectance spectroscopy is particularly effective for the identification of colorants in paintings, manuscripts, polychrome sculpture, and decorative surfaces. Many historical and modern pigments exhibit distinctive absorption features related to electronic transitions or vibrational overtones, allowing them to be recognized even when applied in thin layers or mixed with binders. The technique is well suited to fragile or valuable objects, as it requires no sampling and minimal preparation.

In archaeology, reflectance spectroscopy supports the analysis of wall paintings, ceramics, lithic surfaces, and painted artifacts, helping to differentiate original materials from later interventions, weathering products, or burial alterations. Portable instruments enable in situ measurements, making the method applicable both in museums and in the field.

Reflectance spectroscopy is most powerful when used in combination with other diagnostic tools such as technical photography, X-ray fluorescence (XRF), and infrared reflectography. Together, these approaches provide complementary chemical and optical information, improving material interpretation and supporting informed conservation and research decisions while preserving the integrity of cultural heritage objects.