title: Raman, SEM-EDS and XRPD investigations on pre-Columbian Central America "estucado" pottery.
abstract: Seventeen different colored fragments from six selected pre-Columbian estucado ceramics from El Salvador have been investigated by Raman spectroscopy, scanning electron microscope coupled to an energy dispersive spectrometer (SEM/EDS) and X-ray powder diffraction (XRPD). The peculiarity of this kind of ceramics consist of the unusual presence of a white engobe, traditionally termed stucco, between the ceramic body and the decoration elements, hence the name estucado ceramics. The aim of this work was to study the unusual manufacturing technique and to identify the chemical composition of the engobe and of the pigment palette. The results showed that the stucco layer is made of clay (kaolinite) with traces of titanium oxide (anatase). Remarkably, this is the same composition of the white pigments used for the decoration layer, thus excluding an early use of natural titanium oxide as a white pigment in the estucado productions as suggested in previous investigations. Moreover, the presence of kaolinite and anatase both in the stucco and in the decoration layer suggests a cold-working or low temperature technique. The red, yellow and green decorations were realized by the use of natural ochre, while in all the blue and gray decorations Maya blue pigment was identified. Finally, an amorphous carbon pigment of vegetal origin and manganese oxide were used to obtain black pigments.
authors.affiliation: Università Roma Tre, Dipartimento di Scienze, Via della Vasca Navale 84, 00146 Rome, Italy.
authors.forename: Annalaura
authors.initials: A
authors.lastname: Casanova Municchia
authors.affiliation: Università Roma Tre, Dipartimento di Studi Umanistici, Piazza della Repubblica 10, 00185 Rome, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Micheli
authors.affiliation: Università Roma Tre, Dipartimento di Scienze, Via della Vasca Navale 84, 00146 Rome, Italy.
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Ricci
authors.affiliation: Secretaria de Cultura de la Presidencia de El Salvador, Dirección Nacional de Patrimonio Cultural y Natural, Departamento de Arqueología, San Salvador, El Salvador.
authors.forename: Michelle
authors.initials: M
authors.lastname: Toledo
authors.affiliation: Università Roma Tre, Dipartimento di Scienze, Via della Vasca Navale 84, 00146 Rome, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Bellatreccia
authors.affiliation: Università Roma Tre, Dipartimento di Scienze, Via della Vasca Navale 84, 00146 Rome, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Lo Mastro
authors.affiliation: Università Roma Tre, Dipartimento di Scienze, Via della Vasca Navale 84, 00146 Rome, Italy. Electronic address: sodo@fis.uniroma3.it.
authors.forename: Armida
authors.initials: A
authors.lastname: Sodo
keywords: Anatase; Estucado pottery; Kaolinite; Stucco layer