Reflectance Spectroscopy (RS)

Reflectance Spectroscopy (RS)

In the analysis of polychrome artworks, among the techniques available in a portable version, Reflectance Spectroscopy (RS) has been established as a powerful one for the identification of pigments. The peculiar advantage of this method to the other spectroscopies most commonly used, such as XRF and Raman, is that the RS equipment can be assembled with relatively low-cost components. Reflectance Spectroscopy shows, for each wavelength, the ratio between the intensity of the reflected light and the incident light, measured to a standard white reference (reflectance). The reflectance spectra provide information useful for the identification of pigments.
Reflectance spectroscopy is a powerful non-invasive analytical technique used in art examination to identify and characterize materials, particularly pigments. This method involves measuring the light reflected from the surface of an artwork across different wavelengths, providing a spectral fingerprint that can be used to determine the composition of the materials.
Reflectance spectroscopy works on the principle that different materials can uniquely reflect light. When light is shone on an artwork, certain wavelengths are absorbed by the materials present, while others are reflected. By analyzing the reflected light, it is possible to identify the materials based on their characteristic spectral signatures.

Equipment
Spectrometer: The primary instrument used to measure the intensity of reflected light across a range of wavelengths.
Light Source: Provides a broad spectrum of light, typically including visible, ultraviolet (UV), and near-infrared (NIR) wavelengths.
Fiber Optics: Used to direct light onto the artwork and collect the reflected light for analysis.


Applications in Art Examination
Pigment Identification: Reflectance spectroscopy can identify the specific pigments used in a painting by comparing the measured spectra to reference spectra of known materials. This helps in determining the palette and techniques used by the artist.

Benefits
Non-Invasive and Non-Destructive: Reflectance spectroscopy does not require any physical sampling, making it safe for valuable and delicate artworks.
Rapid and In-Situ Analysis: Measurements can be taken quickly and directly on the artwork, often without the need to move it from its location.

Equipment

Gorgias, our Reflectance Spectroscopy System is specifically designed to examine Art and Archaeology. This spectrometer covers the spectral range 350-1000 nm. 

GorgiasUV, this spectrometer is based on Gorgias but it is optimized to cover a larger UV range up to 200 nm.  reflectance spectroscopy for pigments

FREE Spectra Databases

We offer free spectral databases created with our reflectance spectrometers, Gorgias and Gorgias UV. Visit our Pigments Checker webpage to download them. These databases allow you to instantly compare your analysis with our collections of certified historical and modern art pigments.

FREE Reflectance Spectroscopy Online Course

The FREE Reflectance Spectroscopy (RS) Online Course illustrates the procedures for pigments’ identification using the spectra databases and our spectrometers.

Publications

Publications on Reflectance Spectroscopy
A. Cosentino “FORS spectral database of historical pigments in different binders” e-conservation Journal 2, 57–68, 2014.
A. Cosentino “FORS, Fiber Optics Reflectance Spec­troscopy con gli spet­trometri minia­tur­iz­zati per l’identificazione dei pig­menti” Archeo­mat­ica, 1, 16–22, 2014.
A. Cosentino “Transmittance spectroscopy and transmitted multispectral imaging to map covered paints” Conservar Património 24, 37-45, 2016.
A. Cosentino “Application note 1: Testing GorgiasUV on Pigments Checker” 2021.
A. Cosentino “Application note 4: Gorgias Reflectance Spectra Database for Pigments Checker Modern & Contemporary Art” 2022.
A. Cosentino “Application note #5: Reflectance Spectra Database (GorgiasUV Spectrometer)
for Pigments Checker - Modern & Contemporary Art” 2022.