Potential application of liquid dye penetrants for serial number restoration on firearms

Abstract

Chemical reagents for serial number restoraton are designed to exploit the plastc deformaton zone below the obliterated serial number. Most techniques in operatonal use are variants of Fry's Reagent. This technique uses toxic, corrosive chemicals and requires a skilful operator in the laboratory. Fry's Reagent can also be destructve of the frearm due to rustng. In an atempt to fnd a non-ttoxic, non-tdestructve alternatve to Fry's Reagent, this project tested the use of liquid dye penetrants (LDPs), a non-tdestructve examinaton technique to detect cracks and imperfectons used in the welding industry, for the restoraton of obliterated serial numbers. Steel plates bearing an obliterated serial number with a range of obliteraton depths were subjected to LDP treatment under various treatment conditons.The results using LDPs were negatve for all obliteraton depths and all test conditons atempted. Some of the serial numbers were subsequently restored successfully with Fry's reagent, proving that the plastc deformaton zone was present on the steel plates below the obliteraton. Further work to develop a non-ttoxic, non-tdestructve serial number restoraton process will be undertaken.

Development of etching paste for serial number restoration on aluminum engine block

“…Although full restoration is desired, partial restoration of the engine numbers or VINs may facilitate the identification of vehicles. The literature suggests that chemical etching, magnetic particle inspection, magneto-optic examination, electrochemical analysis, electron backscatter diffraction, and thermographic imaging are used for serial number restoration on metallic surfaces [2][3][4][5][6][7][8][9][10][11][12]. Rather than using real engine blocks or chassis parts for restoration purposes, these studies preferred small metal plates which can be easily analyzed with any technique or device.…”

“…Another issue in the literature is related to the low number of studies conducted on metal alloys. While many restoration research used single metals [2,3,7,[13][14][15], only a few used metal alloys [8,16]. Regarding the development of etching paste on single metal surfaces, there appears to be just one study conducted by Wightman and Matthew [15].…”