10 research outputs found
Multi-analytical study of ceramic pigments application in the study of Iron Age decorated pottery from SW Iberia
A non-invasive multi-analytical approach combining optical microscopy (OM), micro-X-ray diffraction
(mXRD), in-situ X-ray fluorescence spectroscopy (XRF), variable pressure scanning electron microscopy
coupled with energy dispersive X-ray spectroscopy (VP-SEM-EDS) and Raman micro-spectroscopy has
been employed for the first time to investigate the chemical composition of ceramic pigments in
Iberian Iron Age ceramics. The methodology was applied in the study of red, black and white pigments
on Iron Age decorated pottery from the archaeological site of Garvão (SW Portugal). The complementary
methodology adopted in this study minimized the damage to the ancient artefacts and turned out to be
essential in achieving a complete chemical and mineralogical characterization of pigment composition.
Results suggest that haematite (Fe2O3) and pyrolusite (MnO2) are the main mineral carriers of the Fe
and Mn chromophore ions, responsible respectively for the red and black colour. While illite (K(Al,Mg,
Fe)2(Si,Al)4O10(OH)2), a common clay mineral, is giving the white colour. It is the first time that the
use of illite as a pigment on decorations of ancient pottery has been reported in western societies.
The potters used local raw materials, compatible with the regional geological context and the archaeometric
study seems to demonstrate that the society that produced the painted ceramics had limited
access to long commercial routes.This work was financial supported by ‘‘Fundação para a Ciência
e Tecnologia” (FCT), FEDER and compete2020 through the project
PTDC/HIS-ARQ/108758/2008, the PhD grant SFRH/BD/67093/2009
and UID/Multi/04449/2013-POCI-01-0145-FEDER-00764
Ceramic technology. How to characterise ceramic glazes
Glazes add value to ceramic, improve its appearance (colour and shine) and make it waterproof. Through the choice of colours and designs, glazes made ceramics fashionable, even luxurious, and therefore, an object of trade. Each region and ruling dynasty developed its own style or trademark which makes them particularly suitable for dating purposes. Therefore, the study and analysis of glazes offers direct information about the acquisition of technical skills (technology), trade of specific materials (interregional links), migrations and the introduction/adoption of new trends. A ceramic glaze is a thin glassy layer fused to the surface of a ceramic body through firing. The interaction between the glaze and the ceramic body results in the interdiffusion of elements between both. A glaze consists mainly of an amorphous phase, but also includes bubbles, cracks and crystalline phases (undissolved compounds and crystals formed during the firing). Finally, the glazes were also decorated, and a large variety of materials and methods of applying the decorations were used. In this chapter, we present a summary of the technical characteristics of glazes (composition, microstructures and technical requirements), their discovery and use throughout history and decorative techniques. The methodology and analytical techniques to obtain the information are also discussed.Peer ReviewedPostprint (author's final draft