Crystallized Basic Zinc Chromates

Tarr, O. F.; Darrin, Marc; Tubbs, L. G.

doi:10.1021/ja01234a026

Cited by 4 publications

(2 citation statements)

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“…The most stable oxidation states of chromium are Cr(III) and Cr(VI). 20 In Zn yellow, the metal is in the Cr(VI) form, 21,22 whereas the formation of chromic oxide would lead to the presence of Cr (III). 9 XANES spectra of Cr(VI) compounds show a sharp preedge peak at 5993.5 eV, while spectra of Cr(III) compounds present two small pre-edge features at 5990.5 and 5993.5 eV (Fig.…”

Section: X-ray Absorption Spectroscopymentioning

confidence: 99%

The darkening of zinc yellow: XANES speciation of chromium in artist's paints after light and chemical exposures

Zanella

Casadio

Gray

et al. 2011

J. Anal. At. Spectrom.

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The color darkening of selected brushstrokes of the masterpiece A Sunday on La Grande Jatte -1884 (by Georges Seurat) has been attributed to the alteration of the chromate pigment zinc yellow. The pigment originally displays a bright greenish-yellow color but may undergo, after aging, darkening to a dull, ocher tone. We used XANES to probe the oxidation state of Cr on paint reconstructions, and show that color changes are associated with the reduction of Cr(VI) to Cr(III). Paint mixtures containing the pigment and linseed oil to mimic mixtures used in La Grande Jatte were subjected to artificial aging in the presence of light, SO 2 , and variable air humidity-50 and 90% relative humidity. High relative humidity led to the largest degree of Cr(VI) reduction whereas low relative humidity promoted lightinduced alterations. These results are corroborated by visible reflectance measurements on the same laboratory samples and contribute to a better understanding of the chemical reactivity of chromate pigments, which are present in many historical works of art.

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Section: X-ray Absorption Spectroscopymentioning

confidence: 99%

The darkening of zinc yellow: XANES speciation of chromium in artist's paints after light and chemical exposures

Zanella

Casadio

Gray

et al. 2011

J. Anal. At. Spectrom.

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“…Chromate has been found effective also for combating the corrosion of some aluminum systems in strong calcium chloride brine and for preventing the dezincification of brass' in ammoniacontaining brines (18). This laboratory also has obtained interesting results with sparingly soluble complex zinc chromates (24) for inhibiting the corrosion of galvanized systems in calcium chloride brine.…”

Section: Practical Considerationsmentioning

confidence: 99%