1、Designation: E1610 14Standard 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 parenth
2、eses 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 typicallydistinguished by sample size that precludes the application ofmany standard industrial paint analys
3、is procedures or proto-cols. The forensic paint examiner must address concerns suchas the issues of a case or investigation, sample size, complexityand condition, environmental effects, and collection methods.These factors require that the forensic paint examiner choosetest methods, sample preparati
4、on schemes, test sequence, anddegree of sample alteration and consumption that are suitableto each specific case.1.2 This guide is intended as an introduction to standardguides for forensic examination of paints and coatings. It isintended to assist individuals who conduct forensic paintanalyses in
5、their evaluation, selection, and application of teststhat may be of value to their investigations. This guidedescribes methods to develop discriminatory information usingan efficient and reasonable order of testing. The need forvalidated methods and quality assurance guidelines is alsoaddressed. Thi
6、s document is not intended as a detailed methodsdescription or rigid scheme for the analysis and comparison ofpaints, but as a guide to the strengths and limitations of eachanalytical method. The goal is to provide a consistent approachto forensic paint analysis.1.3 This guide cannot replace knowled
7、ge, skill, or abilityacquired through appropriate education, training, and experi-ence and should be used in conjunction with sound profes-sional judgment.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 Some of the metho
8、ds discussed in this guide involve theuse of dangerous chemicals, temperatures, and radiationsources. This guide does not purport to address the possiblesafety hazards or precautions associated with its application.This standard does not purport to address all of the safetyconcerns, if any, associat
9、ed with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatoryrequirements prior to use.2. Referenced Documents2.1 ASTM Standards:2D16 Terminology for Paint, Related Coatings, Materials, andAppli
10、cationsD1535 Practice for Specifying Color by the Munsell SystemE308 Practice for Computing the Colors of Objects by Usingthe CIE SystemE1492 Practice for Receiving, Documenting, Storing, andRetrieving Evidence in a Forensic Science LaboratoryE2808 Guide for Microspectrophotometry and Color Mea-sure
11、ment in Forensic Paint AnalysisE2809 Guide for Using Scanning Electron Microscopy/X-Ray Spectrometry in Forensic Paint ExaminationsE2937 Guide for Using Infrared Spectroscopy in ForensicPaint Examinations3. Terminology3.1 DefinitionsFor definitions of terms used in this guideother than those listed
12、in 3.2, see Terminology D16.3.2 Definitions of Terms Specific to This Standard:3.2.1 additive (modifier)any substance added in a smallquantity to improve properties. Additives may include sub-stances such as driers, corrosion inhibitors, catalysts, ultravio-let absorbers, plasticizers, etc.3.2.2 bin
13、dera non-volatile portion of a paint which servesto bind or cement the pigment particles together.3.2.3 coatinga generic term for paint, lacquer, enamel, orother liquid or liquifiable material which is converted to asolid, protective and/or decorative film after application.3.2.4 discriminateto dist
14、inguish between two samplesbased on significant differences; to differentiate.3.2.5 discriminating powerthe ability of an analyticalprocedure to distinguish between two items of different origin.1This guide is under the jurisdiction of ASTM Committee E30 on ForensicSciences and is the direct respons
15、ibility of Subcommittee E30.01 on Criminalistics.Current edition approved Jan. 15, 2014. Published February 2014. Originallyapproved in 1994. Last previous edition approved in 2008 as E1610 02 (2008).DOI: 10.1520/E1610-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac
16、t ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.6 known samplea coati
17、ng sample of established ori-gin.3.2.7 paintcommonly known as a pigmented coating (see3.2.3).3.2.8 pigmenta finely ground, inorganic or organic,insoluble, dispersed particle. Besides color, a pigment mayprovide many of the essential properties of paint, such asopacity, hardness, durability and corro
18、sion resistance. The termpigment includes extenders.3.2.9 questioned samplea coating sample whose originalsource is unknown.3.2.10 significant differencea difference between twosamples that indicates that the two samples do not have acommon origin.4. Quality Assurance Considerations4.1 Aquality assu
19、rance program must be used to ensure thatanalytical testing procedures and reporting of results aremonitored by means of proficiency tests and technical audits.General quality assurance guidelines may be found in “TraceEvidence Quality Assurance Guidelines” (1).35. Summary of Practice5.1 Paint films
20、 are characterized by a number of physicaland chemical features. The physical characteristics may in-clude color, layer sequence and thickness, surface and layerfeatures, contaminants and weathering. Chemical componentsmay include pigments, polymers, additives and solvents. Thesefeatures can be dete
21、rmined and evaluated by a variety ofmacroscopical, microscopical, chemical, and instrumentalmethods. Limited sample size and sample preservation require-ments mandate that these methods be selected and applied in areasonable sequence to maximize the discriminating power ofthe analytical scheme.5.2 S
22、earching for differences between questioned andknown samples is the basic thrust of forensic paint analysis andcomparison. However, differences in appearance, layersequence, size, shape, thickness, or some other physical orchemical feature can exist even in samples that are known to befrom the same
23、source. A forensic paint examiners goal is toassess the significance of any observed differences. The ab-sence of significant differences at the conclusion of an analysissuggests that the paint samples could have a common origin.The strength of such an interpretation is a function of the typeor numb
24、er of corresponding features, or both.5.3 An important aspect of forensic automotive paint analy-sis is the identification of the possible makes, models and yearsof manufacture of motor vehicles from paint collected at thescene of a crime or accident. The color comparison andchemical analysis of bot
25、h the undercoat and top coat systemsrequires knowledge of paint formulations and processes, col-lections of paint standards, and databases of color and compo-sitional information.5.4 The test procedure selected in a paint analysis andcomparison begins with thorough sample documentation.Some features
26、 of that documentation are described in PracticeE1492.Analysis generally begins with appropriate nondestruc-tive tests. If these initial tests are inconclusive or notexclusionary, the examination may proceed with the selectionof additional tests based on their potential for use in evaluatingor discr
27、iminating the samples of interest, or both.6. Significance and Use6.1 This guide is designed to assist the forensic paintexaminer in selecting and organizing an analytical scheme foridentifying and comparing paints and coatings. The size andcondition of the sample(s) will influence the selected anal
28、yticalscheme.7. Collection of Suitable Samples7.1 The potential for physical matches between known andquestioned samples must be considered before selecting themethod of paint sample collection. Care should be taken topreserve the potential for a physical match.7.2 Questioned Samples:7.2.1 Questione
29、d samples should include all loose or trans-ferred paint materials. Sources of questioned samples caninclude tools, floors, walls, glass fragments, hair, fingernails,roadways, adjacent structures, transfers or smears on vehicles,or transfers to or from individuals such as damaged fabric withpaint in
30、clusions. Whenever possible, items with paint transfersshould be appropriately packaged and submitted in theirentirety for examination. If sampling is necessary, the proce-dures listed in “Trace Evidence Recovery Guidelines” (2) maybe used. When paint evidence is recognized, every effortshould be ma
31、de to manually remove it before using tape lifts tocollect other types of evidence. If paint is collected with tapelifts, one should be aware of the possible difficulty encounteredwhen attempting to manipulate paint samples bearing adhesiveresidues. In addition, components of the adhesive could con-
32、taminate the paint sample and change its apparent chemistry.7.2.2 Smeared transfers can exhibit mingling of componentsfrom several layers or films that could preclude application ofsome of the analytical methods discussed in this guide. Due tothe difficulties associated with collecting smeared or ab
33、radedsamples, the entire object bearing the questioned paint shouldbe submitted to the laboratory whenever possible.7.2.3 When contact between two coated surfaces isindicated, the possibility of cross-transfers must be considered.Therefore, if available, samples from both surfaces should becollected
34、.7.3 Known Samples:7.3.1 When feasible, known paint samples should be col-lected from areas as close as possible to, but not within, thepoint(s) of damage or transfer. Due to the possible presence ofcross transferred materials, these damaged areas are usually notsuitable sources of known samples. Th
35、e collected knownsamples should contain all layers of the undamaged paint film.Substantial variations in thickness and layer sequences overshort distances can exist across a painted surface. This isparticularly true in architectural paint and for automotive films3The boldface numbers in parentheses
36、refer to the list of references at the end ofthis standard.E1610 142where the curves, corners, and edges are often impact pointsand may have been subjected to previous damage, sanding orover-painting. If necessary, several known paint samplesshould be taken to properly represent all damaged areasbec
37、ause different areas of the painted surface may containdifferent paint systems. Known paint samples collected fromdifferent areas should be packaged separately and labeledappropriately.7.3.2 When possible, the surface underlying the suspectedtransfer area should be included for analysis. Sections ad
38、jacentto a suspect transfer area can be valuable for assessingquestioned and known sample differences and evaluating thepossible cross transfer of trace materials.Wall and ceiling, doorand window, implement handle and automobile door, fenderand hood are examples of adjacent items.7.3.3 Paint flakes
39、can be removed from the parent surface bya number of methods. These include, but are not limited to,lifting or prying loosely attached flakes, cutting samples of theentire paint layer structure using a clean knife or blade, ordislodging by gently impacting the opposite side of the paintedsurface. Wh
40、en cutting, it is important that the blade be inserteddown to the parent surface. It should be noted that no onemethod of sampling should be relied upon exclusively.8. Procedure8.1 Discussions of forensic paint analysis are provided indated but detailed form by Crown (3), and more recently byNielsen
41、 (4), Thornton (5), Maehly and Strmberg (6), Stoeck-lein (7), Caddy (8), and Ryland and Suzuki (9).8.2 A reasonable scheme for forensic paint examinations isoutlined in Figs. 1-4. Potentially useful techniques for thediscrimination of paint binders, pigments, and additives arelisted. The major steps
42、 in Fig. 1 are numbered to correspond tothe discussions presented in this guide (for example 8.8,Solvent Tests). For any given comparison, not all the tech-niques listed in the same area in Fig. 1 are necessarily required.Sample size, condition and layer structure complexity shouldbe considered when
43、 determining which techniques to use. Theforensic coatings examiner should always use the more specificand least destructive tests prior to those that require moresample preparation or consumption. A review of the generaltechnique descriptions, listed in 8.8 8.15, will provideguidance for the select
44、ion of appropriate methods.8.3 Fig. 1 does not imply that other examinations should beexcluded or that the order of the procedures in the chart isirrevocable. Samples that are neither constrained by amountFIG. 1 Scheme for Forensic Paint ExaminationsE1610 143nor condition should be subjected to anal
45、yses that will deter- mine the color and texture of the paint as well as the number,FIG. 2 Scheme for Forensic Paint ExaminationsFIG. 3 Scheme for Forensic Paint ExaminationsE1610 144order, colors and textures of the layers in a multi-layeredsample. In most cases, instrumental techniques should beem
46、ployed to analyze and compare both the pigment and binderportions of the sample. A combination of techniques, whichprovide discrimination between as many types of paints andcoatings as possible, should be used. These techniques shouldalso be selected to provide classification and/or componentidentif
47、ication information to be used in significance assess-ments. For samples that are limited in layer structurecomplexity, techniques for the comparison of both the binderand pigment portion of the coating must be used. The choice oftechniques may change depending upon sample characteristics.For instan
48、ce, pyrolysis-gas chromatography (PGC) may beutilized for identifying and comparing the binder portion ofsamples that exhibit a low binder concentration. Likewise,scanning electron microscopy-energy dispersive X-ray analysis(SEM-EDS), X-ray fluorescence (XRF) and X-ray diffraction(XRD) may be used f
49、or identifying and comparing the pigmentportion of samples that exhibit a low pigment concentration.8.4 The flow-chart in Fig. 5 is a guide to the determinationof the possible origins of a motor vehicle paint. It is usuallypossible to differentiate a motor vehicle repaint from theoriginal equipment manufacturer (OEM) paint by microscopi-cal examination of the layer structure. If no OEM paint ispresent, then only the vehicle color (or partial vehicle color)can be reported. For OEM paint, both the topcoat and under-coat layers can be useful in identifying manufactur
