Which chemical is used in the recovery of serial numbers?

The recovery of serial numbers from metal objects, such as firearms or vehicles, often requires the use of chemicals that can reveal hidden markings. Each of the chemicals listed has its own properties that contribute to this process.

Frye's reagent is utilized specifically for the non-destructive restoration of serial numbers on certain metals. It reacts with the residual metal oxides that may remain after the numbers have been ground or stamped over, allowing for the original markings to become visible again.

Nitric acid serves a similar purpose but is more aggressive; its application can remove layers of metal to expose the underlying serial numbers. However, because it is quite corrosive, care must be taken to ensure that the object isn’t further damaged during the recovery process.

Acidic ferric chloride is also used in this context. It etches the surface of metals, allowing for the contrast between the original serial numbers and the altered surface layer caused by the obliteration process.

Because all of these chemicals can be employed in the recovery of serial numbers, the answer that encompasses them all is correct. This makes it important for crime scene investigators to be knowledgeable about the appropriate chemical applications in different scenarios to effectively recover crucial evidence.