Ceramic coatings in ancient times: high technology surface modification technologies

Ceramic coatings on ancient pottery, in particular black gloss, transparent glaze (first alkali based and then lead based) and opaque glaze (enamel) up to the lustre decoration, can be considered as the top technological skill of ancient ceramists. Indeed, their production demands the ceramist a thorough knowledge of pyrotechnology, including the ability to strictly control furnace atmosphere conditions. Several papers have dealt with the study of ceramic coatings, aiming to reconstruct the production technology and the modality of application and to define the relations between coating and ceramic body. These tasks are quite difficult to accomplish, also due to the very fine details of these surface layers. A multianalytical approach is therefore necessary, including conventional (scanning electron microscopy-energy dispersive spectrometry, electron probe microanalyser and Raman) and high resolution techniques (high resolution TEM, synchrotron radiation source based diffraction and X-ray absorption spectroscopy). Two case studies on different ceramic coatings are presented: black gloss pottery from Northern Etruria and Sienese 'Archaic' majolica from Tuscany.