Old Masters' lead white pigments: investigations of paintings from the 16th to the 17th century using high precision lead isotope abundance ratios

Abstract

White lead (2PbCO(3).Pb(OH)(2)), a common component in 17c. artists' painting materials, was singled out to investigate the potential of lead isotope abundance ratios in the field of authentication and origin assignment. Paintings by Peter Paul Rubens, Anthony van Dyck and other Old Masters of the Northern and Southern schools were chosen for this study. An interdisciplinary approach was chosen using both analytical instrumental methods, art technological and art historical knowledge. Minute samples taken from paintings from selected art collections worldwide were investigated using mass spectrometry, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The high precision lead isotope abundance ratios were measured by multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The determination of the calcium matrix influence with respect to possible bias effects to the isotope ratios gave clear decision support, to whether a result lies within the stated combined measurement uncertainty of the result, to eliminate time-consuming matrix separations. The scatter plots of the measured isotope abundance ratios for the painting pigments from P. P. Rubens, A. van Dyck and other Flemish painters exhibit a very narrow distribution forming a cluster. The range of the measured ratio (206)Pb/(204)Pb amounts to 0.55% and for the ratio (207)Pb/(204)Pb to 0.2%. The comparison of the data to cis-alpine (Italian) sample pigments from paintings from the same time period reveals a clear distinction between the two fields. With respect to the lead isotope data originating from the ores it is assumed that the pigment isotope ratio distribution can be explained by very distinct origin of raw materials. Presumably, no mixing of different lead ores from Europe took place. The comparison of the measured white lead isotope ratio values (Flemish paintings) and the data from ore samples led to the unexpected conclusion that local ores were not used for the pigment production but British or German sources.

Isotope Ratio Analysis of Lead in Blood and Environmental Samples by Multi-collector Inductively Coupled Plasma Mass Spectrometry

“…In previous studies, Pb isotope ratio measurements with Tl external standardization have been used. [9][10][11] However, the deleterious effects of the matrix element on the isotope ratios measurement were observed in previous reports 10,[12][13][14][15] as well. Environmental and biological samples, such as soil, house dust, diet and blood samples contain a wide variety of matrix elements (i.e., Ca, Na, Al and Fe).…”

Copper and tin isotopic analysis of ancient bronzes for archaeological investigation: development and validation of a suitable analytical methodology

“…Archaeologists can then match the isotope ratios of individual archaeological artifacts to the fingerprints of their parent ore source, such that archaeological conclusions can be drawn [18][19][20]. In some other instances, provenancing to the original ores is not aimed at, and lead isotopic analysis is used to fingerprint artifacts from a given workshop, period, or any other possible classification and to distinguish or discriminate them from one other [13,17,[21][22][23][24].…”

Inductively Coupled Plasma Mass Spectrometry

“…In case of the Flemish-Dutch painters, comparison to data from different mines revealed, that the lead originated from either Germany or England. 497 Pb isotopic analysis has also been applied for modern forensic purposes, e.g. in order to link a fired projectile to a weapon -as comprehensively assessed by Zeichner et al who carried out firearm cleaning and shooting experiments and found out that a Pb memory effect in the barrel complicates the association.…”