Synchrotron-Based High Angle Resolution and High Lateral Resolution X-ray Diffraction: Revealing Lead White Pigment Qualities in Old Masters Paintings

Abstract

Microsamples collected on 27 major paintings by Old European Masters dating from the 14th to the late 19th centuries were analyzed using synchrotron-based X-ray diffraction. Two complementary analytical configurations were used at beamlines ID22 (high angle resolution) and ID21 (high lateral resolution), in order to highlight markers of the different grades of the lead white pigments (mixture of cerussite PbCO and hydrocerussite Pb(CO)(OH)). Rietveld analysis and crystalline phases mapping at the microscale revealed the composition and microstructure of the pigments, shedding light on the preparation recipes and pigment choices of the artists through History.

Unraveling the Composition of Rembrandt's Impasto through the Identification of Unusual Plumbonacrite by Multimodal X‐ray Diffraction Analysis

“…The composition of the impasto layers and in particular the HC:C ratio is another indication of the alkalinity of the paint. In historical paints, lead white is almost always composed of a mixture of HC and C. The proportion of these two phases can be modulated during the synthesis and post‐synthesis treatments, in particular by washing/grinding in vinegar and heating in water . The synthesis process of lead white used during the Dutch Golden Age is remarkably stable and notably yields a pigment with a “classic” ratio HC:C>70:30 (w %), in agreement with the one measured in the two ground/underlayers studied herein (Figure ).…”

“…However, its presence in older artworks has not been reported. It is notably absent in the large corpus (>35) of historical lead white paints recently studied . Another interesting result was the marginal amount (<10 wt %) of C in these samples, with HC as the main crystalline phase (Figure b).…”

“…In this work, we combined synchrotron high‐angular resolution x‐ray diffraction (HR‐XRD) and micro‐x‐ray diffraction (μ‐XRD) of microscopic fragments sampled from several Rembrandt masterpieces conserved in European museums (Rijksmuseum, Amsterdam; Louvre, Paris; and Mauritshuis, the Hague; Figure ). The advantage of this combined approach for the analysis of historical paint micro‐samples was recently demonstrated with the study of lead‐white‐based paints . Since the main components of the impasto (lead white pigment and oil) are ubiquitous in easel paintings, whether in the paint layers or in the ground layer, we expected subtle differences in the composition of these different layers.…”

Beauty is skin deep: the skin tones of Vermeer’s Girl with a Pearl Earring

“…Several pots were stored in sheds and covered with fermenting (horse) manure, which produces heat and carbon dioxide (CO 2 ) [16]. The stack process leads to the formation of a lead white pigment containing hydrocerussite (HC, basic lead carbonate: Pb 3 (CO 3 ) 2 (OH) 2 ) and cerussite (C, neutral lead carbonate: PbCO 3 ) in a HC:C weight ratio between 60:40 and 80:20 [17]. Changing the synthesis conditions, such as corrosion time or extra supply of CO 2 , could shift this ratio towards a higher hydrocerussite or cerussite quantity.…”

“…The raw material was usually post-processed by paint manufactures or painters themselves-for example, by washing or heating the pigment in water or vinegar-to obtain different grades or qualities of lead white [18]. Heating in water can account for large-sized crystallites and an increase of hydrocerussite [17,18]. Conversely, washing in vinegar can lead to smaller particles and more cerussite.…”