Laboratory tests addressed to realize customized restoration procedures of underwater archaeological ceramic finds

Abstract The present contribution is part of a biennial researchproject funded by the Italian Ministry of Education,Universities and Research (MIUR). This study, currently inprogress, deals with innovative experimental approaches appliedto the chemical, mineralogical and physical transformationsoccurring during the prolonged permanence of archaeologicalceramic finds in seawater environments as wellas to restoration and conservation issues of the same underwaterartifacts. The experimental approach used in this researchconsisted in the manufacture of ceramic test-pieces(briquettes) and their successive placing in underwater environment.This work aims at assessing how textural and compositionalparameters along with firing temperatures of a ceramicpaste could affect total porosity, pore size distributionand kinetics of capillary water absorption. A further purposeis concerned with the study of the potential modification ofporosity and pore size distribution in the same ceramic bodiesafter immersion in seawater (3 and 6 months). The studywas carried out using a multi-technique approach includinginvestigations through polarized light microscopy (PLM), capillary water absorption test, mercury intrusion porosimetry(MIP) analyses and theoretical calculation of salt crystallizationpressures.The obtained results show a different behavior of thesix experimental pastes as a function of their compositionaland textural features as well as pore size distribution andfiring temperatures. These parameters, in various extents,have been found significantly influencing the kinetics of waterabsorption and the susceptibility of ceramic artifacts tosalt crystallization processes, with important implications onconservation procedures needed before the musealization.