Ilaria Borgia

Heterogeneous distribution of metal nanocrystals in glazes of historical pottery

It has been recently shown that lustre decoration of medieval and renaissance pottery consists of silver and copper nanocrystals, dispersed within the glassy matrix of the ceramic glaze. Lustre surfaces show peculiar optical effects such as metallic reflection and iridescence. In many cases, lustre appears overlapped to colored drawings. Here we report the findings of a study on glazes, pigments and lustre of several shards belonging to Deruta and Gubbio pottery of XVI century. The components of glazes and pigments have been identified. Lustre is confirmed to be characterised by silver and copper metal nanocrystals inhomogeneously dispersed in the glassy matrix of the glaze. In the case of lustre overlapped to colored decorations, we found two contradictory cases. The first consists of a lustre surface successfully applied over a blue smalt geometrical drawing. The second consists of a lustre surface, unsuccessfully applied over a yellow lead-antimonate pigment. The yellow pigment hinders the formation of lustre and removes crystals of tin dioxide, normally present in the glaze as opacifier.

Self-calibrated quantitative elemental analysis by laser-induced plasma spectroscopy: application to pigment analysis

Abstract A new laser-based spectroscopic technique, called calibration-free LIPS (laser-induced plasma spectroscopy), is proposed for fast and precise elemental analysis in the field of cultural heritage conservation and study. Quantitative stratigraphic results, obtained by CF-LIPS on ancient Roman frescoe samples, are shown. The application of this calibration-free procedure frees the LIPS technique from the need of reference samples or an internal standard. This characteristic, along with the intrinsic speed (the whole process of data collection and analysis takes a few minutes) and precision (of the order of a few parts percent) make the CF-LIPS a viable technique for in situ quantitative analysis of artworks.

Luminescence from pigments and resins for oil paintings induced by laser excitation

Abstract The present work reports results of an extensive study of laser induced luminescence by tripled Nd:YAG laser ( λ =355 nm) of a few most common painting materials, namely, natural and synthetic pigments and resins. The luminescence spectra have been analyzed by an Optical Multichannel Analyzer (OMA III). Luminescence time decay has been measured by a Streak camera or by the OMA III. Pigments and resins show characteristic emission spectra with bands peaking in the visible. The decay ranges from less than 1 ns up to 700 μ s for pigments and for resins. The mechanism of excitation and relaxation leading to luminescence is discussed for the various materials. Oil colour specimens have been irradiated by a UV KrF laser ( λ =248 nm). Luminescence photographs have been detected by an intensified charge coupled device (ICCD) camera at different time delays.

Microtexture and microchemistry of glaze and pigments in Italian Renaissance pottery from Gubbio and Deruta

Abstract Renaissance ceramic shards from Gubbio and Deruta (Italy) were investigated by scanning and transmission electron microscopy, coupled with energy dispersive spectrometry. The study mainly focuses on the glaze layer, which was applied over the main ceramic body in a second firing process. The glaze contains several inclusions, such as K–feldspar, cassiterite, calcium phosphate and quartz. Most of the shards have blue and yellow decorations, which correspond to the so-called Blue Smalt and Naples Yellow. Overall evidence (glaze bulk-chemistry, the number and type of inclusions, pigment characteristics and the microtextural–microchemical relationships among glaze, inclusions and the main ceramic body) constrains the nature and provenance of raw materials and can be used to estimate firing temperatures in the different processing steps.

Laser diagnostics developed for conservation and restoration of cultural inheritance

Different laser induced diagnostics, originally developed for different purposes including material characterization and environmental monitoring, have been applied in the field of Cultural Inheritance preservation with the aim to facilitate successive conservation and restoration actions. In this paper results relevant to three different techniques are reviewed. The use of topologic laser and 3D sensor in checking small artifacts and large surfaces is discussed, the application of Speckle interferometry to defect analysis of ceramic artwork is represented, a demonstration of the capabilities of a time resolved LIF system in the characterization of surface composition of ancient ceramics and frescoes is finally given.

Studio della tecnica pittorica dei dipinti murali arcaici dell'area dell'ipogeo di C. Genucius Clepsina

Reports on the scientific study of an Etruscan mural painting, dating back to the orientalizing period. Micro-destructive spectroscopic analysis of pigmented fragments has provided some novel information about the Etruscan painting technique. The painting substrate consists of a mixture of finely ground volcanic stone and sedimentary calcareous stone. The substrate is made up of two distinct layers: an outermost layer enriched in calcareous component is superimposed on a lower containing volcanic stone. The orange pigment is hematite (alpha-Fe2O3) while the dark red pigment is a mixture of hematite, maghemite (gamma-Fe2O3) and pyrolusite (beta-MnO2). The white pigment is calcite (CaCO3). Notably, from the painting layer morphology it appears that the pigments were applied in a mixture of lime water. By infrared spectroscopic technique, no trace of organic binder was found.

Fast and Precise Determination of Painted Artwork Composition by Laser Induced Plasma Spectroscopy

In this paper we present recent results of application of a new technique of Laser Induced Plasma Spectral analysis, developed and patented by IFAM-CNR, to the study of painted artworks composition. Thanks to this new approach, a fast and precise determination of paintings composition can be obtained without need for reference samples or calibration curves.