ToF-SIMS investigation of gilt and painted leather: identification of indigo, oil binder and gold varnish

Organic and inorganic compounds of a gilt and painted leather artifact were studied by the use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) technique as part of an in-depth study of this peculiar painting technique. The object under investigation is an altar frontal, coming from the church of San Domenico in Orvieto, which can be dated to the mid-17th century. High mass resolution spectrometry was applied for the chemical characterization of organic materials contained in the gold varnish and paint layer. ToF-SIMS analyses performed on reference compounds and samples from the artifact proved the presence of indigo to depict blue and lead white to depict white areas and the use of an oil binder as resulted by the presence of indigotin, palmitic and stearic acids signals with their diacylglycerols, lead soaps, lead oxides and hydroxides. The analyses have also shown the presence of colophony in the gold varnish. ToF-SIMS results were agreed and integrated with those obtained by other analytical techniques. Copyright (C) 2014 John Wiley & Sons, Ltd.