Serial number restoration on different surfaces

Serial numbers on metal and polymer firearm parts are used for identification and tracing purposes. Stampings on trees and wooden items also serve similar purposes. Restoration, which indicates the recovery of obliterated characters, helps to reveal forgeries, determine the origin and owners of items and solve crimes. This thesis aims to devise new forensic marks examination techniques for restoration. In the first phase of the study conducted on polymers, characters were respectively written on Polyamide 6 and Polyamide 6,6 with hot stamping and laser and then obliteration was carried out by scraping, peening and heating at various depths. Subsequently, the samples were viewed in Video Spectral Comparator 8000 device using different wavelenghts of IR and UV lights and restoration was achieved to a great extent without harming the samples. Cinnamaldehyde and methyleugenol were applied on the same polymers in the second phase of the study and chemical swelling helped to attain success as well. Regarding the metals, cold stamping was used for the writing of characters on aluminum alloy samples and characters were obliterated through milling at varying depths. The etching paste comprising of different metal powders and chemical liquids appeared to be useful in the recovery of characters. Lastly, restoration on wooden surfaces involved using vapor and liquid phases of water, ethanol, ammonia and chloroform at different amounts and durations. While vapor phases apart from chloroform appeared to be useful in restoration, none of the liquid phases gained success. Overall, this thesis contributed to forensic science literature by devising rapid, low-cost and practical restoration techniques efficient on various surfaces. Keywords: Polymer, metal, wooden, obliteration, restoration