DESALINATION OF UNDERWATER CERAMIC CULTURAL HERITAGE: THE EXAMPLE OF KERPE UNDERWATER EXCAVATION

Abstract

Salinity, which is one of the chemical properties of the marine environment, is mixed into seawater due to the dynamic exchange processes between the atmosphere and the hydrosphere and the dissolution of the shells of marine organisms on the seabed. The amount of soluble salts is measured in parts per million (ppm), but in this article, it is measured in parts per thousand (ppt). When soluble salts are not removed by appropriate conservation methods, they crystalize in the pores of artefacts that constitute underwater cultural heritage. These crystals cause physical deterioration in ceramics, which are porous cultural heritage, such as fragmentation from the surface and microscopic cracks. For this reason, the first step in repairing cultural remains recovered from underwater archaeological excavations is to determine the physical properties of the artefacts, such as porosity and salt absorption capacity, as well as the type and amount of salt accumulated in their pores. Thus, the appropriate desalination method can be selected, and estimates can be made on how long the desalination process will take. This paper studied ceramic sherds of Roman and Byzantine amphorae and cooking vessels recovered during underwater excavations in the ancient harbor of Kerpe Bay in Kocaeli, Turkey, in 2022. The aim of the study was to make a preliminary examination for further studies, including instrumental analyses, and to determine the types and amounts of salt deposited on the samples. The samples were desalinated for one month in 200 ml containers with weekly changes of deionized water, and the desalination water was tested to measure salinity and determine the dissolved salt species. Spot tests were used to determine dissolved salts. Sulphate, chloride and carbonate were found in the samples due to these tests. The porosity of the samples was determined by the water absorption method.