Plumbonacrite Identified by X‐ray Powder Diffraction Tomography as a Missing Link during Degradation of Red Lead in a Van Gogh Painting

Abstract

Red lead, a semiconductor pigment used by artists since antiquity, is known to undergo several discoloration phenomena. These transformations are either described as darkening of the pigment caused by the formation of either plattnerite (b-PbO 2 ) or galena (PbS) or as whitening by which red lead is converted into anglesite (PbSO 4 ) or (hydro)cerussite (2 PbCO 3 ·Pb(OH) 2 ; PbCO 3 ). X-ray powder diffraction tomography, a powerful analytical method that allows visualization of the internal distribution of different crystalline compounds in complex samples, was used to investigate a microscopic paint sample from a Van Gogh painting. A very rare lead mineral, plumbonacrite (3 PbCO 3 · Pb(OH) 2 ·PbO), was revealed to be present. This is the first reported occurrence of this compound in a painting dating from before the mid 20th century. It constitutes the missing link between on the one hand the photoinduced reduction of red lead and on the other hand (hydro)cerussite, and thus sheds new light on the whitening of red lead.

On the stability of mediaeval inorganic pigments: a literature review of the effect of climate, material selection, biological activity, analysis and conservation treatments

“…Moreover, it seems that minium promotes the blackening of leadwhite, when the pigments are mixed [204]. Some cases of red lead lightening are reported as well, and are related to the formation of lead sulphates and/or carbonates, according to the atmospheric pollutants and to the initial amount of PbO in red lead [68,93,200,237,238], via the formation of plumbonacrite [228].…”

“…In oil, lead compounds were not only used as pigments, but as siccatives as well [219,220]. Moreover, lead soaps are formed in, or on the surface of, oil paint layers containing lead based pigments (leadwhite, lead tin yellow type I, litharge, red lead) and are investigated as they affect the appearance of paintings [54,55,107,145,[219][220][221][222][223][224][225][226][227][228]. Lead oxalates were observed on leadwhite treated with oxalic acid [32], and on real samples containing red lead and lead tin yellow [56].…”

Zur Photochemie von Künstlerfarben: Strategien zur Verhinderung von Farbveränderungen in Kunstwerken

“…[24][25][26] Untersuchungen einer ausgebleichten Pb 3 O 4 -Probe aus einem Gemälde Va nGoghs führte zur Formulierung des nachfolgend beschriebenen Mechanismus. [24][25][26] Untersuchungen einer ausgebleichten Pb 3 O 4 -Probe aus einem Gemälde Va nGoghs führte zur Formulierung des nachfolgend beschriebenen Mechanismus.…”

“…Mennige oder Bleirot (Pb 3 O 4 )und Titanweiß (TiO 2 )sind zwei andere Halbleiterpigmente,d ie als Photokatalysatoren bekannt sind. [24][25][26] (b). e) Oben:V orgeschlagener Mechanismus der Bildung von a-Hg 3 S 2 Cl 2 ;u nten:lokale Atomstruktur fürreines a-Hg 3 S 2 Cl 2 (links) und defizientes a-Hg 3 S 2 Cl 2 mit einer S-Leerstelle (rechts).…”

Operando 3D Visualization of Migration and Degradation of a Platinum Cathode Catalyst in a Polymer Electrolyte Fuel Cell

“…[9] Computed tomography (CT), which is an effective method for reconstructing 3D images of asample from aseries of transmission images,can be measured with ah ard X-ray probe.Asample is rotated around an axis perpendicular to incident X-ray beam, and aseries of X-ray transmission images are recorded. [9] Computed tomography (CT), which is an effective method for reconstructing 3D images of asample from aseries of transmission images,can be measured with ah ard X-ray probe.Asample is rotated around an axis perpendicular to incident X-ray beam, and aseries of X-ray transmission images are recorded.…”