Evaluation of physical, chemical, and biological degradation of Yenikapı 16 shipwreck and the conservation proposal

The Yenikapı Shipwrecks were unearthed during salvage excavations between 2004-2013 by the Istanbul Archeological Museums. Documentation of 27 shipwrecks and conservation and analyses of 31 shipwrecks have been carried out in Istanbul University, Division of Conservation of Marine Archaeological Objects. The Yenikapı (YK) 16 shipwreck, which is the subject of this thesis study, has a special significance in the shipwrecks group since it is a galley that is thought to be used in the Byzantine navy. When the waterlogged woods of the YK 16 shipwreck dated to the 8-9th century AD were uncovered, it was found that they were degraded and not to be in good condition. Within the scope of the study, various analyses were carried out to investigate the extent and causes of the degradation. For this reason, maximum water content (Umax), density, and wood substance loss calculations were performed to determine the degree of physical degradation of the samples taken from the shipwreck. In the calculations, the maximum water content of the samples were found to be between %336-1467; density values were between 0.07-0.25 g/cm3; values of the wood substance loss were between %84-842.85. In addition, deformations occurring in the cell structure of wood and physical damages were determined by imaging on the samples with the SEM analysis. It was determined that the cellulose, hemicellulose, and lignin sections, constituting the chemical structure of the wood, were degraded by FT-IR analysis on the samples. Furthermore, the presence of iron, sulfur, calcium, etc. elements in the wood was detected with the XRF analysis in order to determine the chemical degradation. As a result of all these instrumental analyses, a comprehensive examination of the changes in the waterlogged woods of the shipwreck was carried out. In addition, pH measurements were performed regularly to understand the chemical structure better. As a result of the evaluation of the data obtained, it has been decided to complete the conservation by using melamine formaldehyde for the highly degraded woods and the PEG pre-impregnated vacuum freeze-drying method for those woods which are relatively in better condition.