Abstract: A Novel Use of TLC-SERS to Detect Fugitive Blues and Yellows in Historic Paintings

Hey there!

My name is Mary. I’m a rising senior at the College majoring in chemistry. This is my first summer doing research here in Williamsburg and I’m incredibly excited to continue the work I’ve been doing over the last year.  Over the next few months, I’ll be expanding on my work in art conservation and pigment identification.

Organic pigments, including many blues and yellows that combine to create rich greens, are prone to fading. What one often sees in historical works of art are leaves and floral elements that have turned blue since the yellow pigments have faded. In the chemistry lab we act as detectives searching for clues to identify these faded pigments. Luckily, we have our trusty laser and spectroscopy instruments to help us out.

Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) have been used to identify individual organic paints in dispersed paint samples and painting cross sections.  Paints derive their color from pigment chromophores, each of which yields a unique Raman spectrum. Optimal spectra are obtained when only one pigment (and thus only one chromophore) is present in the area of the sample being analyzed. However, if blue and yellow pigments are mixed together to create a green optical mixture their chromophores interfere resulting in a noisy, unidentifiable spectra.

Mixing paints is common in artists’ methods, especially in the creation of greens. I am designing a process that eliminates the signal noise associated with optical mixtures and identifies the blue and yellow pigment components of relevant paint samples. I plan to use thin-layer chromatography (TLC), a process which dissolves and separates unique molecules, to differentiate the blue and yellow components of green optical mixtures and facilitate positive identification of pigments. While I will start on a model paint mixture of known composition, the end goal is to analyze unknown mixtures from historic works of art using this novel combination of TLC and SERS.

Thanks for reading! Check back this summer for more lasertastic updates!

Comments

  1. cmcrowley01 says:

    I find your research rad because it sits at a symbiotic intersection between science and art! The liberal arts gods would be proud. When you analyze these unknown paint mixtures, are you trying to find out what the original composition of the mixture was and how much the yellows have faded? Good luck with your work.