Serial Number Restoration
Serial Number – A unique number typically applied to an object by a manufacturer Serial Number Restoration – The practice of restoring an obliterated serial number by using scientific methods
Types of Serial Numbering Application Methods Serial numbers can be applied in a variety of methods. Each method has unique characteristics which enable them to be differentiated from each other.
Dot Matrix Dot matrix engraved serial numbers are fairly shallow and are made by a succession of dots
Laser Engraving Serial numbers engraved with a laser are shallow and have a “burned” appearance.
Stamped Serial Numbers Stamped serial numbers are made by using a stamp with a positive impression of a number and applying sufficient pressure to impart a negative impression of the stamp on the object
Stamped Serial Numbers
Stamped Serial Numbers - Theory The compressed area at the base of the stamping is strained below the surface of the stamp mark
Obliteration � When serial numbers are obliterated, they are generally ground down beyond the lowest point of the original stamping. n n This results in the visible portion of the serial number being removed. By removing the serial number, criminals hope that the object can not be identified as having been stolen.
Obliteration � The serial number is no longer visible due to the removal of the top layer of the metal. � The area below the obliterated layer is affected by the stamping process and is the reason serial number restoration is possible.
Visualizing Restorations Serial numbers appear when they are acid etched due to specular reflection. ◦ Specular reflection – light reflecting off a smooth surface ◦ Diffuse reflection – light reflection off rough surfaces Specular Reflection Smooth Surface Diffuse reflection Rough Surface
Serial Number Restoration An obliterated serial number typically has a surface that has been scratched so that the number is no longer recognizable
Serial Number Restoration The first step in the process of restoring the serial number is to polish the surface by using sand paper in progressively finer grits. Polishing the surface will help in visualizing the serial number.
Serial Number Restoration Acid Etching – The acid reacts with the metal and produces hydrogen gas bubbles
Serial Number Restoration The result of the acid etching is a restored serial number. The dark appearance of the numbers is the result of diffuse reflection.
Case Studies An ATV was suspected of having been stolen from a local dealership. When police attempted to read the VIN (Vehicle Identification Number) it was observed that it had been obliterated. The number in question was located on the engine
Case Studies The surface with the obliterated number was located on the top of the engine block
Case Studies This is the area on top of the engine where the VIN number was stamped. The first step in the restoration process will be to sand it smooth.
Case Studies After the surface was sanded, Acid was applied to the engine block.
Case Studies The Vehicle Identification Number was restored to H 310 E-06674. Using this information, police were able to verify the ATV was stolen and press charges against the suspect. H 31 0 E-06674