7: Glass, Ceramics and Enamelled Objects

Much like weapons, vessels made from glasses and ceramics have long been held as objects of very high technology. Ceramic technology mastery is even at the foundation of metallurgy. In producing glass, pottery and enamelled metals, three critical and energy intensive steps are needed: obtaining fine powder, firing, and building appropriate kilns. Control of the colour also requires advanced physical and chemical knowledge. Indeed, if ceramic production is somewhat the art of forming a heterogeneous matter (only some components melt), glass or enamel production requires the object to pass through a homogeneous liquid state to obtain the desired microstructure and properties. This chapter presents the different destructive, non-destructive and non-invasive analytical methods that can be carried out in a laboratory on shards or sampling with fixed ‘big’ instruments, or on-site (museums, reserves, etc.) with mobile set-ups. After a brief overview of the history of pottery, the implications of the processes involved (grinding, shaping, sintering, enamelling, decoration) on micro- and nano-structures (formation and decomposition temperature, kinetic and phase rules, sintering) is given. Emphasis is given to information that can be obtained by XRF and Raman mobile non-invasive measurements. Examples illustrating how these studies help to document technology exchanges and exchange routes are also given.