1、Designation: E1610 17E1610 18Standard Guide forForensic Paint Analysis and Comparison1This standard is issued under the fixed designation E1610; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in
2、 parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 Forensic paint analyses and comparisons are typically distinguished by sample size that precludes the application of manystandard industrial pai
3、nt analysis procedures or protocols. The forensic paint examiner must address concerns such as the issuesof a case or investigation, sample size, complexity and condition, environmental effects, and collection methods. These factorsrequire that the forensic paint examiner choose test methods, sample
4、 preparation schemes, test sequence, and degree of samplealteration and consumption that are suitable to each specific case.1.2 This guide is intended as an introduction to standard guides for forensic examination of paints and coatings. It is intendedto assist individuals who conduct forensic paint
5、 analyses in their evaluation, selection, and application of tests that maycan be ofvalue to their investigations. This guide describes methods to develop discriminatory information using an efficient and reasonableorder of testing. The need for validated methods and quality assurance guidelines is
6、also addressed. This document is not intendedas a detailed methods description or rigid scheme for the analysis and comparison of paints, but as a guide to the strengths andlimitations of each analytical method. The goal is to provide a consistent approach to forensic paint analysis.1.3 This guide c
7、annot replace knowledge, skill, or ability acquired through appropriate education, training, and experience andshould be used in conjunction with sound professional judgment.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
8、1.5 Some of the methods discussed in this guide involve the use of dangerous chemicals, temperatures, and radiation sources.This guide does not purport to address the possible safety hazards or precautions associated with its application. This standarddoes not purport to address all of the safety co
9、ncerns, if any, associated with its use. It is the responsibility of the user of thisstandard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatorylimitations prior to use.1.6 This international standard was developed in accordance with in
10、ternationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D16
11、Terminology for Paint, Related Coatings, Materials, and ApplicationsD1535 Practice for Specifying Color by the Munsell SystemE308 Practice for Computing the Colors of Objects by Using the CIE SystemE1492 Practice for Receiving, Documenting, Storing, and Retrieving Evidence in a Forensic Science Labo
12、ratoryE2808 Guide for Microspectrophotometry and Color Measurement in Forensic Paint AnalysisE2809 Guide for Using Scanning Electron Microscopy/X-Ray Spectrometry in Forensic Paint ExaminationsE2937 Guide for Using Infrared Spectroscopy in Forensic Paint Examinations3. Terminology3.1 DefinitionsFor
13、definitions of terms used in this guide other than those listed in 3.2, see Terminology D16.3.2 Definitions of Terms Specific to This Standard:1 This guide is under the jurisdiction of ASTM Committee E30 on Forensic Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.C
14、urrent edition approved Sept. 1, 2017Feb. 15, 2018. Published September 2017February 2018. Originally approved in 1994. Last previous edition approved in 20142017as E1610 14.E1610 17. DOI: 10.1520/E1610-17.10.1520/E1610-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or conta
15、ctASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been
16、 made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.
17、Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.1 additive (modifier)any substance added in a small quantity to improve properties. Additives maycan include substancessuch as driers, corrosion inhibitors, catalysts, ultraviolet ab
18、sorbers, plasticizers, etc.3.2.2 bindera non-volatile portion of a paint which serves to bind or cement the pigment particles together.3.2.3 coatinga generic term for paint, lacquer, enamel, or other liquid or liquifiable material which is converted to a solid,protective, decorative, or combination
19、thereof, film after application.3.2.4 discriminateto distinguish between two samples based on significantmeaningful differences; to differentiate.3.2.5 discriminating powerthe ability of an analytical procedure to distinguish between two items of different origin.3.2.6 known samplea coating sample o
20、f established origin.3.2.7 meaningful differencea feature or property of a sample that does not fall within the variation exhibited by the comparisonsample, considering the limitations of the sample or technique, and therefore indicates the two samples do not share a commonorigin. The use of this te
21、rm does not imply the formal application of statistics.3.2.8 paintcommonly known as a pigmented coating (see 3.2.3).3.2.9 pigmenta finely ground, inorganic or organic, insoluble, dispersed particle. Besides color, a pigment maycan providemany of the essential properties of paint, such as opacity, ha
22、rdness, durability, and corrosion resistance. The term pigment includesextenders.3.2.10 questioned samplea coating sample whose original source is unknown.3.2.10 significant differencea difference between two samples that indicates that the two samples do not have a commonorigin.4. Quality Assurance
23、 Considerations4.1 Aquality assurance program must be used to ensure that analytical testing procedures and reporting of results are monitoredby means of proficiency tests and technical audits. General quality assurance guidelines may be found in “Trace Evidence QualityAssurance Guidelines” (1).35.
24、Summary of PracticeGuide5.1 Paint films are characterized by a number of physical and chemical features. The physical characteristics maycan includecolor, layer sequence and thickness, surface and layer features, contaminants, and weathering. Chemical components maycaninclude pigments, polymers, add
25、itives, and solvents.These features can be determined and evaluated by a variety of macroscopical,microscopical, chemical, and instrumental methods. Limited sample size and sample preservation requirements mandate that thesemethods be selected and applied in a reasonable sequence to maximize the dis
26、criminating power of the analytical scheme.5.2 Searching for differences between questioned and known samples is the basic thrust of forensic paint analysis andcomparison. However, differences in appearance, layer sequence, size, shape, thickness, or some other physical or chemical featurecan exist
27、even in samples that are known to be from the same source. A forensic paint examinersexaminers goal is to assess thesignificance of any observed differences.The absence of significantmeaningful differences at the conclusion of an analysis suggeststhat the paint samples could have a common origin. Th
28、e strength of such an interpretation is a function of the type or number ofcorresponding features, or both.5.3 An important aspect of forensic automotive paint analysis is the identification of the possible makes, models, and years ofmanufacture of motor vehicles from paint collected at the scene of
29、 a crime or accident.The color comparison and chemical analysisof both the undercoat and top coat systems requires knowledge of paint formulations and processes, collections of paint standards,and databases of color and compositional information.5.4 The test procedure selected in a paint analysis an
30、d comparison begins with thorough sample documentation. Some featuresof that documentation are described in Practice E1492. Analysis generally begins with appropriate nondestructive tests. If theseinitial tests are inconclusive or not exclusionary, the examination may proceed with the selection of a
31、dditional tests based on theirpotential for use in evaluating or discriminating the samples of interest, or both.6. Significance and Use6.1 This guide is designed to assist the forensic paint examiner in selecting and organizing an analytical scheme for identifyingand comparing paints and coatings.
32、The size and condition of the sample(s) will influence the selected analytical scheme.7. Collection of Suitable Samples7.1 The potential for physical matches between known and questioned samples must be considered before selecting the methodof paint sample collection. Care should be taken to preserv
33、e the potential for a physical match.3 The boldface numbers in parentheses refer to the list of references at the end of this standard.E1610 1827.2 Questioned Samples:7.2.1 Questioned samples should include all loose or transferred paint materials. Sources of questioned samples can includetools, flo
34、ors, walls, glass fragments, hair, fingernails, roadways, adjacent structures, transfers or smears on vehicles, or transfersto or from individuals such as damaged fabric with paint inclusions. Whenever possible, items with paint transfers should beappropriately packaged and submitted in their entire
35、ty for examination. If sampling is necessary, the procedures listed in “TraceEvidence Recovery Guidelines” (2) maycan be used. When paint evidence is recognized, every effort should be made to manuallyremove it before using tape lifts to collect other types of evidence. If paint is collected with ta
36、pe lifts, one should be aware of thepossible difficulty encountered when attempting to manipulate paint samples bearing adhesive residues. In addition, componentsof the adhesive could contaminate the paint sample and change its apparent chemistry.7.2.2 Smeared transfers can exhibit mingling of compo
37、nents from several layers or films that could preclude application of someof the analytical methods discussed in this guide. Due to the difficulties associated with collecting smeared or abraded samples,the entire object bearing the questioned paint should be submitted to the laboratory whenever pos
38、sible.7.2.3 When contact between two coated surfaces is indicated, the possibility of cross-transfers must be considered. Therefore,if available, samples from both surfaces should be collected.E1610 1837.3 Known Samples:7.3.1 When feasible, known paint samples should be collected from areas as close
39、 as possible to, but not within, the point(s)of damage or transfer. Due to the possible presence of cross transferred materials, these damaged areas are usually not suitablesources of known samples. The collected known samples should contain all layers of the undamaged paint film. Substantialvariati
40、ons in thickness and layer sequences over short distances can exist across a painted surface. This is particularly true inarchitectural paint and for automotive films where the curves, corners, and edges are often impact points and may have beensubjected to previous damage, sanding, or over-painting
41、. If necessary, several known paint samples should be taken to properlyrepresent all damaged areas because different areas of the painted surface maycan contain different paint systems. Known paintsamples collected from different areas should be packaged separately and labeled appropriately.7.3.2 Wh
42、en possible, the surface underlying the suspected transfer area should be included for analysis. Sections adjacent to asuspect transfer area can be valuable for assessing questioned and known sample differences and evaluating the possible crosstransfer of trace materials. Wall and ceiling, door and
43、window, implement handle and automobile door, and fender and hood areexamples of adjacent items.7.3.3 Paint flakes can be removed from the parent surface by a number of methods. These include, but are not limited to, liftingor prying loosely attached flakes, cutting samples of the entire paint layer
44、 structure using a clean knife or blade, or dislodging bygently impacting the opposite side of the painted surface. When cutting, it is important that the blade be inserted down to the parentsurface. It should be noted that no one method of sampling should be relied upon exclusively.8. Procedure8.1
45、Discussions of forensic paint analysis are provided in dated but detailed form by Crown (3), and more recently by Nielsen(4), Thornton (5), Maehly and Strmberg (6), Stoecklein (7), Caddy (8), and Ryland and Suzuki (9).8.2 A reasonable scheme for forensic paint examinations is outlined in Figs. 1-4.
46、Potentially useful techniques for thediscrimination of paint binders, pigments, and additives are listed. For any given comparison, not all the techniques listed in thesame area in Fig. 1 are necessarily required. Sample size, condition, and layer structure complexity should be considered whendeterm
47、ining which techniques to use. The forensic coatings examiner should always use the more specific and least destructivetests prior to those that require more sample preparation or consumption. A review of the general technique descriptions, listed in8.8 8.15, will provide guidance for the selection
48、of appropriate methods.8.3 Fig. 1 does not imply that other examinations should be excluded or that the order of the procedures in the chart isirrevocable. Samples that are neither constrained by amount nor condition should be subjected to analyses that will determine thecolor and texture of the pai
49、nt as well as the number, order, colors, and textures of the layers in a multi-layered sample. In mostcases, instrumental techniques should be employed to analyze and compare both the pigment and binder portions of the sample.A combination of techniques, which provide discrimination between as many types of paints and coatings as possible, should beused.These techniques should also be selected to provide classification or component identification information, or both, to be usedin significance assessments. For samples that are limited in layer structure comple
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