Laboratory multi-technique study of Spanish decorated leather from the 12th to 14th centuries.

This work comprises an exhaustive study of Spanish decorative leathers dating from the 12th to 14th centuries. These paintings are considered a key example of a crucible of artistic styles: Gothic, Islamic and Florentine Trecento. The goal of this work was to use the scientific information provided by a number of experimental techniques - namely EDX, micro-FTIR, micro-Raman and micro-XRD - to assess the dating of the wooden vault, leather preparation and filling fibres.

Spanish and Portuguese Gilding Threads: Characterization Using Microscopic Techniques.

Gilding threads collected from Spanish and Portuguese palaces and from the embroideries and adornments of sculptures of the Virgin and Christ that form part of Sevillian Holy Week were analyzed and compared (20 artifacts were evaluated). The study covered a broad time period with examples from the 13th to 14th centuries, 18th to 20th centuries, and also including modern embroideries. A combination of scanning electron microscopy and energy-dispersive X-ray spectroscopy was used.

A new approach to the determination of the synthetic or natural origin of red pigments through spectroscopic analysis.

This work suggests a way of differentiation between the natural or synthetic origin of inorganic materials that were historically used in the Cultural Heritage field. An exhaustive review of different reported procedures of synthesis of pigments was conducted, as well as a review of the accompanying minerals in case of natural pigments. The natural or synthetic origin of the pigments studied in this work was performed through the characterization of the accompanying minerals, in the case of the natural pigments, or the trace elements that are present as part of synthesis by-products or washing/purifying reagents and/or reactants that have only been partly removed in the final steps of these processes.

Wall paintings studied using Raman spectroscopy: a comparative study between various assays of cross sections and external layers.

This work describes a comparative study between in situ applications of portable Raman spectroscopy and direct laboratory measurements using micro-Raman spectroscopy on the surface of small samples and of cross sections. The study was performed using wall paintings from different sites of the Alcazar of Seville. Little information was obtained using a portable Raman spectrometer due to the presence of an acrylic polymer, calcium oxalate, calcite and gypsum that was formed or deposited on the surface.

Sonication induced redox reactions of the Ojén (Andalucía, Spain) vermiculite.

Sonication in a 1:1 mixture (volume ratio) of water and concentrated H(2)O(2) (30%) is a soft method for particle size reduction of phyllosilicate minerals like vermiculites. Repeated sonication causes a particle size reduction to about 70 nm for the Santa Olalla and to 45 nm for the Ojén-vermiculite. In this context the question arises whether the strong oxidising effect of the hydrogen peroxide affects the oxidation state of the iron in the vermiculites.

Surface and interlayer structure of vermiculite intercalated with methyl viologen.

Molecular modeling using empirical force field revealed the differences between the surface and interlayer arrangement of the dye guest molecules in vermiculite intercalated with the divalent methyl viologen cation (MV(2+)). Conformation and anchoring of MV(2+) cations on the silicate layer in the interlayer space of vermiculite host structure is different from that on the crystal surface. A preferential position has been found for the anchoring of guests on the silicate layer.