Spectroscopic studies on the darkening of lead white

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DOIResolve DOI: http://doi.org/10.1366/000370203322554563
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Journal titleApplied Spectroscopy
Pages13931398; # of pages: 6
AbstractLead white is an historically important paint used by artists since antiquity. The darkening of lead white has been well documented in works of art such as paintings. In this paper, mid-infrared (MIR) and visible spectroscopy were used to examine spectral changes accompanying the darkening of lead white paint as a result of exposure to H₂S(g). Laboratory-prepared paint and a commercial lead white paint were used to observe the darkening reaction over time. Structural changes to the pigment, 2PbCO₃·Pb(OH)₂, in lead white were readily detected using MIR by applying a thin film on a KBr pellet. Spectral changes at 3541 (O-H stretch), 1400 (C-O), and 680 cm⁻¹ (C-O) were the most significant over time as the paint darkened. Visible spectra were also collected to provide a semi-quantitative measure of color change with structural changes observed by MIR. Experiments in the visible region were also conducted to compare the spectral response as % reflected and % transmitted light as lead white darkened. The effect of different binding agents (egg tempera, linseed oil, water, and gum Arabic) on the rate of darkening of lead white was also examined. Other sulfur-containing pigments such as orpiment and realgar were also tested for their ability to darken lead white. By applying paint as a thin film inside a sealed cuvette, darkening of lead white was observed in the visible spectra (800 nm) when either powdered orpiment or realgar was in placed in the cuvette for 24 h.
Publication date
AffiliationNRC Institute for Biodiagnostics; National Research Council Canada
Peer reviewedNo
NRC publication
This is a non-NRC publication

"Non-NRC publications" are publications authored by NRC employees prior to their employment by NRC.

NRC number2089
NPARC number9148458
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Record identifier6b2e4645-bc40-4c9a-a9d4-abdeef318ef8
Record created2009-06-25
Record modified2016-05-09
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