PRESERVATION OF ANCIENT METALLIC ARTIFACTS FROM SHIPWRECKS USING A NATURAL COATING

A major concern of nautical archeologists is the preservation of water-logged archeological findings. Metal findings tend to corrode, which can lead to irreversible damage or even destruction, specifically with iron-based objects. This problem is particularly severe in artifacts retrieved from shipwrecks. There are several solutions for this issue, including treating the metal so as to make it corrosion resistant, or isolating the object from the corrosive environment. The goal of this research is to test a cleaning and coating procedure for iron-based archeological findings retrieved from shipwrecks. Our aim was to produce a cheap and transparent corrosion-resistant coating whose application is simple and reversible, and can be performed in field conditions. The following variables were defined in our experiments: materials (low carbon steel and cast iron), cleaning agents and procedure, coating materials and procedure, corrosive environment, and time. The measurements taken included weight, density, volume, identification of the material, mechanical and chemical properties, and the reaction to the corrosive environment due to the specific coating. The instruments used included: SEM EDS, DSC, XRF, FTIR, GCMS, RAMAN etc. While several types of coating were tested, a multilayered coating based on bee-wax and (3-mercaptopropyl)trimethoxysilane provided a tremendous improvement in corrosion resistance for both laboratory specimens and actual archeological findings: an anchor from the Tantura F shipwreck and nails from the Akko 1 shipwreck. Our results indicate that a cheap, natural, transparent, and reversible coating of this sort is capable of improving corrosion resistance for a long period of time and can be performed in field condition.

KEYWORDS: Akko 1 iron nails, Corrosion resistance, Natural coating, Preservation, Tantura F Anchors.