Pigments

Introduction

What pigments were used to paint a work of art or to decorate an ancient artifact? While that work was being created, did an artist run out of materials and need to use pigments from another supply source? Or was there perhaps more than one team of artists, using pigments from non-identical sources? Were there later repairs? Are we looking at a forgery? Understanding how a specific work of art was created is also vital knowledge before it can be restored. These questions and more can be investigated by understanding the elemental chemistry of pigments. I collaborate with members of Binghamton Art Museum and Dr. Hilary Becker of the Dept. of Middle Eastern and Ancient Mediterranean Studies at Binghamton University to  address these questions using data collected with a handheld X-ray fluorescence spectrometer. 

Current Projects

Unmixing Pigments: A Statistical Approach for Art and Artifacts. (Dr. J. Pietras, Dr. H. Becker)

X-ray fluorescence spectroscopy is a proven technique to identify pigments on art and archaeological artifacts. Knowledge of pigment composition aids in provenance studies, detecting forgery, and recognizing restorations among other topics. XRF data can be used to differentiate pigments within a family of colors based on subtle chemical variability; however, this requires detailed investigation of each spectrum. Calculating the relative abundance of mixed pigments is also challenging. This issue is compounded now that elemental maps are routinely collected consisting of thousands of datapoints. This study investigates the utility of a statistical model, positive matrix factorization (PMF), to unmix pigments based on elemental concentration data from XRF analysis of known pigment mixtures. PMF modeling provides a fingerprint and relative abundance of statistically significant factors from large datasets. Elemental fingerprints will be compared to the composition of the starting pigments, and their relative abundances will be compared to the known mixtures. Gaining better understanding of mixtures is an important step forward in the scientific study of pigments. A successful outcome from this study, using a set of known pigments and known mixtures, will provide the PI’s with the proof-of-concept data needed to seek external funds for future research of unknown mixtures.

Recent Projects

Publications