Technology for preserving surface features of ancient finds in sea water

Archaeological iron objects found in sea water are coated with large amounts of mineralised iron and CaCO3 deposits with the presence of micro and macrobiological components. The aim of the present work is to propose techniques for avoiding detaching of or damage to mineralised iron featured on surface layers and deposits generated by long immersion in a sea-water environment. These elements can actually be the source of important historical information but can be rapidly degraded by successive exposure to the atmosphere. The importance of controlling the pH, redox potentials and osmotic pressure of the solution before the first period of conservation has been pointed out. Moreover, a decrease in surface tension of the liquid phase during drying has been recognised as a critical aspect in avoiding the crack–splitting phenomena of the surface layers. Correct extraction of the chloride through an electrochemical process is fundamental to ensuring the correct storage of finds during successive exposure to the atmosphere. This operation can be implemented by controlling the current density and distribution, thus avoiding development of the gas phase. Technology suitable for performing this operation is described.