A review of the phenomenon of lead white darkening and its conversion treatment

Understanding the (in)stability of semiconductor pigments by a thermodynamic approach

“…(2) Another clear example is the light-induced oxidation of the black lead white degradation product PbS to white PbSO 4 , an old restoration treatment proposed in the 17th century by Norgate in his "Miniatura or the Art of Limning": 'bleaching' (i.e., formation of white PbSO 4 ) is induced by exposure to strong natural light. In the 20th century, an acceleration of the bleaching process was remarked when the object was damp [17]. Thus, light in the presence of water is able to oxidize PbS, as expected from Fig.…”

Unveiling one of the rarest ‘butterflies’ ever (Lepidoptera: Hesperiidae, Noctuidae)

“…Mabille & Boullet, ), clearly does not help in this respect, but examination of the NHMUK holdings of Achlyodes busirus did not lead to the discovery of any specimen of this species derived from Milne. Other Drury Lepidoptera types have been subsequently recovered in Milne's material at the BM (Authors' Team, ; Horn & Kahle, ). The holotype of E. contigua perfectly matches illustrations of Hesperia busiris made by Jones from Drury's original specimen. In addition to the dorsal and ventral sides of wings, the abdominal pattern also agrees, which can be assessed from the illustration of the contigua holotype in Butler () made before this was dissected. A difference in the coloration of the forewing apices and hindwing margins, white in the specimen and grey in Jones's illustrations, partly so in Donovan's, corresponds to what is observed in many of the white‐coloured parts of other butterflies portrayed by Jones (R.I. Vane‐Wright, personal communication), a phenomenon known as lead ‘white darkening’, which commonly affects old paintings in which lead was used as a component of white dyes (Lussier & Smith, ). The fact that Fabricius () mentions grey apices too gives a hint that he may have based his description on Jones's artwork rather than on the original specimen, so Donovan () should have so done for his picture.…”

Hydrofluoric acid pre-treatment of matte artists’ paints for binding medium analysis by Fourier transform infrared microspectroscopy

“…Furthermore, a series of tiny black dots were printed over the surface of the image to indicate shading. Most of the thickly applied white highlights, which were the last artistic elements applied, have turned gray or are severely blackened, suggesting that the pigment is lead white which has darkened to lead(II) sulfide (PbS) as a result of exposure to hydrogen sulfide (H2S) or carbonyl sulfide (COS) pollution [30]. This often occurs in unvarnished artworks executed in a water-based medium.…”

“…Although further treatment with vapor phase HF or direct contact with the reagent solution could further eliminate the lead carbonate, this level of residual interference is not enough to obscure the unexpected features of a drying oil at 2931, 2858, 1734, 1238, 1169, and 1106 cm -1 . Although lead white in oil is usually not prone to reaction with sulfide pollution, its underbound state in painting ground layers and in thickly applied oil paste highlights could expose the white surface pigment to the action of polluted atmospheres [30].…”