Joan Piquero-Cilla

Electrochemical analysis of gildings in Valencia altarpieces: a cross-age study since fifteenth until twentieth century

The application of the voltammetry of microparticles methodology to the study of gildings in paintings and architectural ornaments is described. Nanosamples from pieces from different churches of the Comunitat Valenciana (Spain) covering since the fifteenth century until nowadays were studied upon attachment to graphite electrodes in contact with aqueous HCl and H2SO4 electrolytes. Electrochemical measurements, combined with field emission scanning electron microscopy X-ray microanalysis (FESEM-EDX) and atomic force microscopy (AFM) data, denoted that a common manufacturing technique was used with minimal variations along time. The relationship between specific voltammetric features associated to bulk gold and active surface sites, however, changed monotonically with time, thus suggesting the possibility of age monitoring.

Electrochemical analysis of gold embroidery threads from archeological textiles

A methodology for characterizing archeological gold embroidery threads based on two analytical techniques is described: Field emission scanning electron microscopy (FESEM-EDX) and voltammetry of immobilized microparticle (VIMP) methodologies. After the analysis of the chemical composition of the metallic foil, we analyze specific voltammetric features associated with the oxidation of gold in contact with aqueous H2SO4 and HCl electrolytes. Cyclic and square wave voltammetries (VMP) have been used to get information about the elemental composition and the corrosion products of the samples. AFM, FESEM-EDX, and FESEM-FIB-EDX methodologies complete the study and bring us closer to the composition of the alloys and the embroidery manufacture techniques. This technique actualizes the VIMP data and evidences the morphological and elemental differences between them; in particular, it is confirmed that Au-Ag-Cu alloys, with notably differences in Ag content depending on the provenance, were used.