Optimization of Copper Stain Removal from Marble through the Formation of Cu(II) Complexes in Agar Gels

Copper complexes with different ligands (ethylenediaminetetraacetic acid, EDTA, ammonium citrate tribasic, TAC, and alanine, ALA) were studied in aqueous solutions and hydrogels with the aim of setting the optimal conditions for copper stain removal from marble by agar gels, with damage minimization. The stoichiometry and stability of copper complexes were monitored by ultraviolet-visible (UV-Vis) spectroscopy and the symmetry of Cu(II) centers in the different gel formulations was studied by electron paramagnetic resonance (EPR) spectroscopy. Cleaning effectiveness in optimized conditions was verified on marble laboratory specimens through color variations and by determining copper on gels by inductively coupled plasma-mass spectrometry (ICP-MS). Two copper complexes with TAC were identified, one having the known stoichiometry 1:1, and the other 1:2, Cu(TAC)2, never observed before. The stability of all the complexes at different pH was observed to increase with pH. At pH 10.0, the gel\u2019s effectiveness in removing copper salts from marble was the highest in the presence of ALA, followed by EDTA, TAC, and pure agar gel. Limited damage to the marble surface was observed when gels with added EDTA and TAC were employed, whereas agar gel with ALA was determined to be the most efficient and safe cleaning material

Tackling the Challenging Determination of Trace Elements in Ultrapure Silicon Carbide by LA-ICP-MS

The goal of accurately quantifying trace elements in ultrapure silicon carbide (SiC) with a purity target of 5N (99.999% purity) was addressed. The unsuitability of microwave-assisted acid digestion followed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis was proved to depend mainly on the contamination induced by memory effects of PTFE microwave vessels and by the purity levels of acids, even if highly pure ones were used in a clean environment. A new analytical protocol for the direct analysis of the solid material by laser ablation coupled with ICP-MS (LA-ICP-MS) was then exploited. Different samples were studied; the best results were obtained by embedding SiC (powders or grains) in epoxy resin. This technique has the great advantage of avoiding any source of external contamination, as grinding, pressing and sintering pretreatments are totally unnecessary. Two different laser wavelengths (266 and 193 nm) were tested, and best results were obtained with the 266 nm laser. The optimized protocol allows the determination of elements down to the sub-mg/kg level with a good accuracy level

La tavolozza di Francesco Hayez. Riflessioni intorno alla materia dell\u2019arte ottocentesca

Il progetto ha previsto l\u2019analisi di sedici dipinti del sommo pittore del Romanticismo italiano Francesco Hayez, tramite le tecniche non invasive di riflettografia e spettroscopia infrarossa. I risultati principali sono stati la definizione della tavolozza pittorica dell\u2019artista e la redazione di un repertorio commentato sulle ricerche storico-artistiche e archivistiche sui materiali e sulle tecniche della pittura italiana ottocentesca. I contenuti derivanti dalle indagini chimiche e storico-artistiche sono stati tradotti in itinerari formativi ed educativi, anche sperimentando nuove modalit\ue0 comunicative facenti uso di dispositivi tecnologici e con un approccio interdisciplinare ed hands on

INTERNATIONAL JOURNAL OF CONSERVATION SCIENCE ARE COMMERCIAL PIGMENTS RELIABLE REFERENCES FOR THE ANALYSIS OF PAINTINGS?

International audienceWhen paintings are examined by spectroscopic techniques, building a robust database is of major importance, in order to compare the analyses with reliable references and to correctly understand the results. The database, which is usually homemade, should include carefully chosen commercial pigments, which should be as pure as possible and should correspond to the expected formula or composition of the historical pigments. Unfortunately, sometimes no correspondence between the names of the pigments used by companies and the actual composition of some of the colors is ascertained. In some cases, the composition is in fact made up of different chemical compounds; in others the presence of extenders is revealed, for example gypsum and calcite. In this paper some cases studies are discussed, regarding commercial pigments analysed by infrared spectroscopy, thermal analysis, X-ray diffraction and X-ray fluorescence. The results highlighted the importance of checking the purity of commercial pigments and excluding any extraneous compounds while interpreting the results of analytical survey of paintings

Hellenistic Mortar and Plaster from Contrada Mella near Oppido Mamertina (Calabria, Italy)

International audienceRecent archaeological investigations conducted at contrada Mella, an alluvial terrace near Oppido Mamertina, in southwestern Calabria, have uncovered the remains of a town that was settled by the Tauriani, an Italic people, between the third and the first centuries BC. A unique deposit excavated in 1990 and 1992 yielded numerous fragments of mortar and painted plaster associated with Hellenistic pottery and other cultural materials. Chemical analyses of samples of these fragments, point to the use of aerial mortars with hematite and calcite as pigments. The characteristics of the mortar and painted plaster found at contrada Mella are comparable to those of similar materials from Locri Epizephyrii, the closest Greek city on the Ionian coast of Italy, and from Hellenistic sites in Calabria and Sicily. They provide new evidence for interior decoration from the houses of the Tauriani

Hellenistic Mortar and Plaster from Contrada Mella near Oppido Mamertina (Calabria, Italy)

International audienceRecent archaeological investigations conducted at contrada Mella, an alluvial terrace near Oppido Mamertina, in southwestern Calabria, have uncovered the remains of a town that was settled by the Tauriani, an Italic people, between the third and the first centuries BC. A unique deposit excavated in 1990 and 1992 yielded numerous fragments of mortar and painted plaster associated with Hellenistic pottery and other cultural materials. Chemical analyses of samples of these fragments, point to the use of aerial mortars with hematite and calcite as pigments. The characteristics of the mortar and painted plaster found at contrada Mella are comparable to those of similar materials from Locri Epizephyrii, the closest Greek city on the Ionian coast of Italy, and from Hellenistic sites in Calabria and Sicily. They provide new evidence for interior decoration from the houses of the Tauriani