Restoration Of Serial Numbers Research Articles

Development of etching paste for serial number restoration on aluminum engine block.

Engine numbers, which involve information regarding the engine type, production number, and year and place of manufacture, are used for identification purposes. Comprising of unique alphanumeric characters, the engine numbers are fully or partially obliterated especially in auto theft and smuggling cases to conceal the origin, identity, and owner of vehicles. The limitations of the current restoration techniques such as the difficulty of using chemical liquid etching in vertical sites, the restrictions of magnetic and optical methods, and the applicability of several techniques like electron backscatter diffraction only in the laboratory environment prompt the development of new techniques. In view of these limitations and the importance of restoring engine numbers in criminal investigations, this unique study aimed to develop an etching paste that would restore the effaced characters on a real aluminum alloy engine block. The characters which were cold-stamped on the engine block were milled at varying depths and restoration attempts were conducted using etching pastes formed with different chemicals and materials. The analyses indicate that the etching paste formed with 200 mg of perlite, 400 mg of iron powder, and 450 μL of 20 M NaOH provided restoration to a good extent. The prevention of over-etching through the controlling of the chemical reaction and the cost-effectiveness appears to be the advantages of this technique. The success of recovery on the real engine block, the facilitation of restoration on curved surfaces, and the chance of on-site usage will likely make the etching paste a widely used tool in serial number restoration.

Digital Technologies for Analysis of Restoration of Serial Numbers

In daily activities, serial numbers represent one way to range finished products of different types of production fields and also tracking those objects during their lifetime – ever since their exit of the production site until their recycling. In this paper are presented several types of imprinting techniques as well as a case study for restoration of a modified serial number.

A spectroscopic approach for rapid and simple serial number restoration on polyamide 6 parts of firearms: The use of video spectral comparator 8000.

Serial numbers have forensic value as they help to identify firearms. While the serial numbers are mostly stamped on the metal parts of firearms, the characters on polymer parts involve non-serial number information such as caliber, brand, model, or proof marks, which also serve for identification purposes. The forensic evidence indicates that the polymer frames of firearms bearing non-serial number information are obliterated through heating and scraping. Although the destructive restoration techniques for polymers are well-documented, there is little theoretical and practical knowledge regarding the non-destructive restoration techniques applied on polymers. In view of this gap, this study aims to devise a non-destructive spectral technique to recover the obliterated characters on Polyamide 6. Considering its wide use on polymers, the numbering is carried out by hot stamping and the numbers are defaced through heating, scraping, and hammering both superficially and deeply at varying depths. Herein, we focused on imitating the manual obliteration techniques used by criminals instead of the deepness-controlled techniques preferred by previous studies. The samples are then viewed under the UV and IR lights in the Video Spectral Comparator 8000 for the first time. The results suggest that spectral imaging provided restoration to a good extent after heating and scraping which made the characters invisible at a relatively low depth of deformation compared to hammering. The recovery of characters with this novel technique brings a new perspective forensic marks examination literature by producing quick, successful and reliable results and facilitating reexamination by not harming the sample.

Serial number restoration on polymer surfaces: A survey of recent literature

Polymers are increasingly preferred for the production of weapon parts due to their lightness, resistance to corrosion, heat tolerance and quite reasonable production cost. This increase will likely lead to a rise in the obliteration of serial numbers, which are imprinted on the polymer components of vehicles and firearms. However, compared to metals, the recovery process and the restoration procedures do not seem to be well documented for polymers. Since serial numbers, together with the proof marks and wording related to the brand, model, caliber or manufacturer information, can be regarded as unique in identifying and tracing the vehicles and firearms, the restoration of these alphanumeric codes is vital in determining the items’ origin and owner. Best to our knowledge this is the first review examining the conventional and the recently developed serial number restoration techniques applied on polymer surfaces. This review endeavoured to examine the empirical studies related to serial number restoration on polymers both to demonstrate the scope and evolution of restoration efforts and to give insight into the mechanisms of revisualization and the impact of polymer composition on numbering, obliteration and restoration. The findings indicate that parameters like polymer type, numbering style, obliteration method and techniques used in the restoration process affect the recovery. The findings also suggest that there is an increase in the number of studies applying non-destructive screening techniques for restoration purposes. This review contributes to the literature by outlining the empirical studies and proposing likely avenues for prospective research on restoration techniques which are importantboth for the forensic marks examination and criminal investigations.

Advances in firearm serial number restoration

Advances in firearm serial number restoration

Potential application of liquid dye penetrants for serial number restoration on firearms

Chemical reagents for serial number restoration are designed to exploit the plastic deformation zone below the obliterated serial number. Most techniques in operational use are variants of Fry’s Reagent. This technique uses toxic, corrosive chemicals and requires a skilful operator in the laboratory. Fry’s Reagent can also be destructive of the firearm due to rusting. In an attempt to find a non-toxic, non-destructive alternative to Fry’s Reagent, this project tested the use of liquid dye penetrants (LDPs), a non-destructive examination technique to detect cracks and imperfections used in the welding industry, for the restoration of obliterated serial numbers. Steel plates bearing an obliterated serial number with a range of obliteration depths were subjected to LDP treatment under various treatment conditions. The results using LDPs were negative for all obliteration depths and all test conditions attempted. Some of the serial numbers were subsequently restored successfully with Fry’s reagent, proving that the plastic deformation zone was present on the steel plates below the obliteration. Further work to develop a non-toxic, non-destructive serial number restoration process will be undertaken.

Restoration of Obliterated Numbers on 40NiCrMo4 Steel by Etching Method: Metallurgical and Statistical Approaches.

The restoration of obliterated serial numbers is a problem of common occurrence in the forensic field. Among several restoration techniques, chemical etching is the most frequently used. The present research is aimed at studying the restoration of serial numbers, stamped on 40NiCrMo4 steel plates, by means of chemical etching. Microstructural characterization was firstly carried out to study the plastically deformed regions surrounding the marks. The obliteration was performed by controlled removals of material at increasing depths of erasure, and five etching reagents were considered to analyze their sensitivity and effectiveness. Experimental results revealed that Fry's reagent was the most sensitive, able to restore erased marks up to 60 μm under the depth of the imprint. The reagent comprising 25 mL HNO3 and 75 mL H2O provided good results, recovering the major numbers of characters. A descriptive statistical analysis was conducted to study the operator's influence on the recovered marks' identification.

Firearm Serial Number Restoration with Electron Backscatter Diffraction

Journal Article Firearm Serial Number Restoration with Electron Backscatter Diffraction Get access Ryan M White, Ryan M White National Institute of Standards and Technology, Boulder, CO USA Search for other works by this author on: Oxford Academic Google Scholar Robert R Keller Robert R Keller National Institute of Standards and Technology, Boulder, CO USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 21, Issue S3, 1 August 2015, Pages 1363–1364, https://doi.org/10.1017/S1431927615007606 Published: 23 September 2015

The restoration of serial numbers on vehicle glass using hydrofluoric acid

Very little research has been carried out investigating techniques for the restoration of obliterated serial numbers on vehicle glass. A study into the effectiveness of hydrofluoric (HF) acid, a known etchant for glass, has been performed. Character sequences previously etched into panes of vehicle glass were sanded to varying depths and attempts were made to restore the sequences by polishing and using a range of concentrations of HF acid. A concentration of 30% HF acid gave at least a 50% restoration of the sequence if up to approximately 30μm of glass had been removed during obliteration. Recovery improves if less glass is removed, but not if the concentration of the acid is increased. It appears that removal of glass below the level of the original characters makes subsequent restoration using this technique impossible.

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).

A survey of some metallographic etching reagents for restoration of obliterated engraved marks on aluminium–silicon alloy surfaces

A brief survey to assess the sensitivity and efficacy of some common etching reagents for revealing obliterated engraved marks on Al-Si alloy surfaces is presented. Experimental observations have recommended use of alternate swabbing of 10% NaOH and 10% HNO(3) on the obliterated surfaces for obtaining the desired results. The NaOH etchant responsible for bringing back the original marks resulted in the deposition of some dark coating that has masked the recovered marks. The coating had been well removed by dissolving it in HNO(3) containing 10-20% acid. However, the above etching procedure was not effective on aluminium (99% purity) and Al-Zn-Mg-Cu alloy surfaces. Also the two reagents (i) immersion in 10% aq. phosphoric acid and (ii) alternate swabbing of 60% HCl and 40% NaOH suggested earlier for high strength Al-Zn-Mg-Cu alloys [23] were quite ineffective on Al-Si alloys. Thus different aluminium alloys needed different etching treatments for successfully restoring the obliterated marks. Al-Si alloys used in casting find wide applications especially in the manufacture of engine blocks of motor vehicles. Hence, the results presented in this paper are of much relevance in serial number restoration problems involving this alloy.

The Potential Application of EBSD to Serial Number Restoration

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Application of Magnetic Principles to the Restoration of Serial Numbers

Application of Magnetic Principles to the Restoration of Serial Numbers