Development of new reagent for restoration of erased serial number on metal plates

Serial numbers are used as unique identification marks for a range of items, but these can be erased by offenders involved in criminal activities such as theft or illegal use of stolen items, so that the origin and ownership cannot be traced. Nowadays many methods are available to restore the erased serial number. Chemical etching is the most common and successful method for restoration of serial numbers on the metal surface.About 10 different reagents of which most of them are copper and iron containing, less toxic, less hazardous compounds were chosen for etching. The erased surfaces were etched with every one of these etchants using the swabbing method. The relative sensitivity and efficiency of these reagents in recovering marks obliterated by grinding are described on the basis of experimental results observed. Here the best results were achieved with the use of etching reagent No. 4 (composition; ferric chloride 25 g, conc. HCl 25 ml, distilled water 100 ml).