| Crooks that scratch off the serial numbers of their | | | | metal around it. The numbers immediately come into |
| firearms are not as smart as they believe. There are | | | | view. Applying an electrical current (electrochemical |
| several methods that forensic firearms investigators | | | | etching) speeds up the process. This method is |
| use at their disposal for finding hidden serial numbers. | | | | disadvantageous because it changes the physical |
| All the methods have a common denominator: | | | | makeup of the evidence. If the forensic scientist |
| Whenever metal is pressure stamped, not only does | | | | overindulges in this method, he can destroy the |
| the metal have indentations of numbers, but the | | | | evidence for good. |
| metal underneath the numbers contains resultant | | | | - Ultrasonic cavitation method--This particular method |
| structural abnormalities. | | | | is a destructive method like chemical etching. In this |
| There are three methods for revealing missing serial | | | | method, the forensic scientist puts the firearm in a |
| numbers: | | | | special ultrasonic bath and inundates it with super high |
| - Magnaflux method--The forensic scientist first | | | | frequency vibrations. These vibrations produce the |
| magnetizes the firearm. Magnetizing produces ripples | | | | cavitation. Cavitation is the process when tiny bubbles |
| of magnetic forces used to locate where the metal is | | | | are produced along the surface of the metal. With |
| disordered from the pressure stamping process. He | | | | repeated exposure, the process of cavitation starts |
| then sprays the firearm with an oil that suspends any | | | | eating away at the metal. Cavitation will eat away |
| iron-like particles. These particles tend to settle in | | | | metal in the places where the metal is disordered, |
| places where the metal is disordered. This reveals the | | | | thus revealing the serial number. |
| location of the hidden serial number. This method is | | | | If an offender attempts to file off serial numbers on |
| advantageous because it is not destructive and does | | | | a firearm he used in a crime, there are scientific ways |
| not change the weapon in any way. | | | | to reveal the serial number no matter how much of |
| - Chemical and electrochemical etching method--The | | | | the number has been destroyed. Finding such a |
| forensic firearm examiner paints what is known as an | | | | number can help solve a crime and bring the |
| etching solution over the area in question. The | | | | perpetrator to justice. |
| solution etches the disordered metal quicker than the | | | | |