Scientific Analysis of Fine Art with FTIR

Scientific analysis of fine art

Knowing exactly what components comprise an artwork makes it possible to date art objects and verify their authenticity. Knowing this also helps conservators apply the best treatment procedures as they restore paintings and other pieces of art.

Understanding these components in great detail can be a difficult task since artists’ paints are combinations of pigments, fillers, and binders that have spanned many materials over time.

FTIR analysis

To get insights they need, today’s art conservators are turning to the scientific analysis. One of the most common techniques is Fourier transform infrared spectroscopy (FITR) analysis, which enables them to identify the chemical makeup of paints, fillers and binders using an infrared light source to measure absorption.

Unfortunately, many FTIR analysis sampling techniques, including transmission and attenuated total reflectance, require the removal of tiny samples from the painting for analysis.

Non-contact, non-destructive FTIR analysis

In contrast, FTIR reflectance spectroscopy offers a non-contact, non-destructive method of analysis. Using the Thermo Scientific ConservatIR FTIR External Reflection Accessory for reflectance analysis, art conservationists can characterize various artists’ paints without making direct contact with the painting. At the same time, they eliminate the need to remove a sample from the artwork in order to examine it.

ConservatIR FTIR External Reflection Accessory

Rather than putting samples into a sample compartment, the artwork is placed in front or above the spectrometer sample compartment, and an integrated camera captures a magnified image of the sampled spot. This allows for easy analysis without the risk of damaging the artwork.

The full range of FTIR reflectance measurements

 Using the ConservatIR FTIR External Reflection accessory together with a Nicolet FTIR spectrometer, FTIR reflectance spectroscopy works well when applied to paint measurements in both the mid-IR and end-IR spectral regions. In our own tests, for example, we used mid-IR reflectance measurements to easily identify an acrylic paint containing Pyrrole Red developed in the 1980s as well as an oil paint containing the pigment Prussian Blue, which was first synthesized in 1704. We were also able to determine the presence of alumina trihydrate, a filler that enhances the color in paints.

ConservatIR External Reflection Accessory image of Prussian Blue oil paint

The far-IR measurements can be particularly useful when paints contain inorganic pigments that typically have only weak or no mid-IR spectral signatures. For example, we used far-IR reflectance measurements to differentiate Zinc White and Titanium White after seeing that their acrylic binder rendered the mid-IR region of the two spectra nearly identical.

Finally, we used FTIR reflectance measurements in both regions to determine the difference between the cadmium yellow pigment, commercially available since 1919 and benzimidazolone yellow, a synthetic organic pigment introduced in the late 1970s.

Accurate information for the scientific analysis of fine art

As art conservationists work to authenticate and restore artwork, many are turning to FTIR analysis. FTIR reflectance spectroscopy with the ConservatIR FTIR External Reflection Accessory offers a non-contact, non-destructive form of analysis, providing the accurate information they need to make well-informed decisions.

To learn more, see our application note, Non-contact and non-destructive analysis of artists’ paints by reflectance FTIR.

Ron Rubinovitz is a Senior Applications Scientist at Thermo Fisher Scientific.