In stainless steel or cast iron, this process, when combined with the polishing procedure, is a successful approach to recover an obliterated serial number. To speed up the etching process, this solution can be used in combination with a rectifier.Solution E (Ferric Chloride)The Solution E (Ferric Chloride) process is a chemical etching procedure for restoring serial numbers in hard cast aluminium, mild steel, or brass when used in conjunction with the polishing procedure.25% Nitric AcidThis is a chemical etching process for restoring serial numbers in steel, aluminium, and its alloys when used in conjunction with the polishing procedure.
Serial Number RestorationDuring the manufacturing process, legally produced firearms are stamped with a uniquely identifying serial number, usually on the barrel or action. These numbers are stamped into the firearm, a process which also impresses the digits below the surface of the metal. Even though criminals may attempt to erase these serial numbers to avoid the weapon being traced, it may be possible to restore these serial numbers to a state in which they are legible. Serial numbers are often erased by filing or grinding, which will not necessarily remove the digits below the surface. Alternatively the perpetrator may attempt to change the serial number. Various techniques and reagents have been used to successfully restore these original numbers.
Magnaflux Serial Number Restoration Reagents
An alternative method of restoring serial numbers on iron or steel is the Magnaflux method. As in the chemical etching method, the surface to be treated is first smoothed. A magnet is then attached behind the area and a mixture of iron filings mixed in a light oil is added to the surface. These minute metallic pieces will hopefully arrange themselves to visualise each digit. This technique is particularly beneficial due to its non-destructive nature, however it is not effective on all types of metal.
Similar to serial numbers are proof marks, markings imprinted on a firearm specific to the manufacturer or testing facility. These unique imprints are applied to a weapon before it is released and after any significant repair work is conducted on the firearm.
Both the MO sensor technology and the standard MPI methods use strong magnetic fields to reveal obliterated numbers, which requires that the firearms be magnetic. To reveal destroyed serial numbers on weapons made of nonmagnetic materials, such as zinc, aluminum or alloy substances, crime laboratories must still use chemical etching, a process that uses strong acids and typically reveals a serial number for only a few moments before possibly destroying it.
Whether it be MO, MPI or chemical etching, an obliterated serial number can often be recovered from a metal weapon because when a manufacturer stamps the serial number into the barrel or frame, the crystalline structure of the metal below the number is deformed and compacted. Because of the structural changes in the underlying metal, even when the visible serial number is filed or ground away, the material structure below retains the number.
During phase one testing, Luyendijk was concerned about cost. The sensor was mounted in an industrystandard viewing system that was priced at about $15,000. In addition, each of the multilayered sensors cost about $2,200, and they were not very durable. The system, mounted in a box, also could not read serial numbers on curved surfaces or hard-to-reach areas, such as the barrel or handle of a handgun. 2ff7e9595c
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