A set of laboratory experiments has been developed to determine the nature and importance of the interaction between clay bodies and lead glazes during firing following different thermal paths (firing time and temperature, cooling rates) and using different glaze compositions and different bodies (illitic, kaolinitic, and calcareous clays). It is shown that the interaction consists of a digestion/diffusion process. This process involves (i) decomposition of the phases forming the clay body (digestion), (ii) chemical diffusion of elements between clay body and glaze, and (iii) formation of a layer (interface between clay and glaze) of small K-Pb feldspar crystallites.

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Tin oxide (SnO 2 ) particles that are a few hundred nanometers in size and are embedded in a lead glaze act as a white opacifier. The insolubility of SnO 2 particles in a lead glaze is responsible for this microstructure. Although it is assumed that SnO 2 particles do not react during the glaze formation, we demonstrate that the development of metastable phases prior to the fusion of the PbO-SiO 2 -SnO 2 mixture allows the SnO 2 particles to react and then recrystallize subsequent to the fusion of the mixture. The recrystallization of SnO 2 occurs during heating and/or cooling until the temperature is sufficiently low and/or the tin supply is exhausted.

Resins obtained from Pinus genus species have been widely used in very different fields throughout history. As soon as they are secreted molecular changes start altering their chemical, mechanical and optical properties. The ageing processes are complex and chemical and structural changes associated to resin degradation are not yet fully known. Many questions still remain open, for instance changes happening in pimaranes, one of the two diterpenoid constituents of the resin.A systematic study of the ageing process of Pinus resins is done through of Fourier Transform Infrared Spectroscopy (FTIR) using chemical standards and complementing obtained results with Gas Chromatography coupled to Mass Spectrometry (GC/MS) analysis when necessary. Moreover, long-term degradation processes are also investigated through the analysis of a selection of dated historical resins. The study overcomes the limitations of GC/MS and brings new information about the reactions and interactions between molecules during Pinus resin ageing process, providing information about bonds affected and unaffected and can be used as specific markers of the degradation and of the resins themselves.

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