ANALYSIS AND CONSERVATION OF AN IRON AGE DAGGER FROM TALL ABU AL-KHARAZ, JORDAN VALLEY: A CASE STUDY

Abstract

The aim of this study is to report from the analyses of a corroded iron dagger from the Iron Age city at Tall Abu al-Kharaz, Jordan Valley, and to present the conservation procedures. Preliminary condition assessment was carried out by visual examination and stereomicroscope. X-ray radiography was used to reveal surface details under the external deposits and corrosion layers. X-ray diffraction (XRD) analysis was used to identify the mineralogical composition of the corrosion products. Polarized light microscopy (PLM) was used to examine a cross-section taken from the dagger to determine its corrosion profile and internal metallographic microstructure. The dagger’s radiograph showed that the edges and tip of the dagger were its weakest and most corroded parts. XRD results showed that goethite (α-FeOOH), lepidocrocite (γ-FeOOH) and magnetite (Fe3O4) were the main corrosion products. PLM examination showed that the dagger had greatly converted into magnetite. It also showed signs of hammering, carburization and heat treatment during the manufacturing process of the artifact. The dagger was treated by immersion in an alkaline solution to extract any chloride ions present in the artifact. It was then treated with tannic acid to produce a coherent film of black ferric tannate. Finally, it was coated with Paraloid B72 to consolidate it and protect it from atmospheric humidity and corrosive ions in the environmentally uncontrolled storage area.