1、Designation: E 1610 02Standard Guide forForensic Paint Analysis and Comparison1This standard is issued under the fixed designation E 1610; 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 paren
2、theses indicates the year of last reapproval. Asuperscript epsilon (e) 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 ana
3、lysis 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 prepar
4、ation 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
5、in 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.
6、This 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 Some of the methods discussed
7、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, associated with its u
8、se. 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:D 16 Terminology Relating to Paint, Varnish, Lacquer, andRelated Products2D 15
9、35 Method for Specifying Color by Munsell System2E 308 Test Method for Computing the Colors of Objects byUsing the CIE System2E 1492 Practice for Receiving, Documenting, Storing, andRetrieving Evidence in a Forensic Science Laboratory33. Terminology3.1 DefinitionsFor definitions of terms used in thi
10、s guideother than those listed in 3.2, see Terminology D 16.3.2 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 dryers, corrosion inhibitors, catalysts, ultravio-let absorb
11、ers, plasticizers, etc.3.2.2 bindera 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 appli
12、cation.3.2.4 discriminateto distinguish 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.3.2.6 known samplea coating sample of established ori-gin.3.2.7 paintcomm
13、only known as a pigmented coating (see3.2.3).3.2.8 pigmenta finely ground, inorganic or organic, in-soluble, dispersed particle. Besides color, a pigment mayprovide many of the essential properties of paint, such asopacity, hardness, durability and corrosion resistance. The termpigment includes exte
14、nders.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 A quality assurance program must be used to ensure thatanal
15、ytical testing procedures and reporting of results aremonitored by means of proficiency tests and technical audits.1This guide is under the jurisdiction of ASTM Committee E30 on ForensicSciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.Current edition approved Nov. 1
16、0, 2002. Published January 2003. Originallypublished as E 1610 94. Last previous edition E 1610 95 (2001).2Annual Book of ASTM Standards, Vol 06.01.3Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United St
17、ates.General quality assurance guidelines may be found in “TraceEvidence Quality Assurance Guidelines” (1).45. Summary of Practice5.1 Paint films are characterized by a number of physicaland chemical features. The physical characteristics may in-clude color, layer sequence and thickness, surface and
18、 layerfeatures, contaminants and weathering. Chemical componentsmay include pigments, polymers, additives and solvents. Thesefeatures can be determined and evaluated by a variety ofmacroscopical, microscopical, chemical, and instrumentalmethods. Limited sample size and sample preservation require-me
19、nts mandate that these methods be selected and applied in areasonable sequence to maximize the discriminating power ofthe analytical scheme.5.2 Searching for differences between questioned andknown samples is the basic thrust of forensic paint analysis andcomparison. However, differences in appearan
20、ce, layer se-quence, size, shape, thickness, or some other physical orchemical feature can exist even in samples that are known to befrom the same source. A forensic paint examiners goal is toassess the significance of any observed differences. The ab-sence of significant differences at the conclusi
21、on of an analysissuggests that the paint samples could have a common origin.The strength of such an interpretation is a function of the typeand/or number of corresponding features.5.3 An important aspect of forensic paint analysis is theidentification of the possible makes, models and years ofmanufa
22、cture of motor vehicles from paint collected at the sceneof a crime or accident. The color comparison and chemicalanalysis of both the undercoat and top coat systems requires aknowledge of paint formulations and processes, collections ofpaint standards, and databases of color and compositionalinform
23、ation.5.4 The test procedure selected in a paint analysis andcomparison begins with thorough sample documentation.Some features of that documentation are described in PracticeE 1492. Analysis generally begins with appropriate nonde-structive tests. If these initial tests are inconclusive or notexclu
24、sionary, the examination may proceed with additionaltests, which are selected, based on their potential for use inevaluating and/or discriminating the samples of interest.6. Significance and Use6.1 The guide is designed to assist the forensic paintexaminer in selecting and organizing an analytical s
25、cheme foridentifying and comparing paints and coatings. The size andcondition of the sample(s) will influence the selected analyticalscheme.7. Collection of Suitable Samples7.1 The potential for physical matches between known andquestioned samples must be considered before selecting themethod of pai
26、nt sample collection. Care should be taken topreserve the potential for a physical match.7.2 Questioned Samples:7.2.1 Questioned samples should include all loose or trans-ferred paint materials. Sources of questioned samples caninclude tools, floors, walls, glass fragments, hair, fingernails,roadway
27、s, adjacent structures, transfers or smears on vehicles,or transfers to or from individuals such as damaged fabric withpaint inclusions. Whenever possible, items with paint transfersshould be appropriately packaged and submitted in theirentirety for examination. If sampling is necessary, the proce-d
28、ures listed in “Trace Evidence Recovery Guidelines” (2) maybe used. When paint evidence is recognized, every effortshould be made 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 enco
29、unteredwhen attempting to manipulate paint samples bearing adhesiveresidues. In addition, components of the adhesive could con-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 applic
30、ation ofsome of the analytical methods discussed in this guide. Due tothe difficulties associated with collecting smeared or abradedsamples, the entire object bearing the questioned paint shouldbe submitted to the laboratory whenever possible.7.2.3 When contact between two coated surfaces is indi-ca
31、ted, the possibility of cross-transfers must be considered.Therefore, if available, samples from both surfaces should becollected.7.3 Known Samples:7.3.1 When feasible, known paint samples must be collectedfrom areas as close as possible to, but not within, the point(s)of damage or transfer. These d
32、amaged areas are usually notsuitable sources of known samples. The 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 pa
33、int and for automotive filmswhere 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 areas.Known paint samples collected from differe
34、nt areas should bepackaged separately and labeled appropriately.7.3.2 When possible, the surface underlying the suspectedtransfer area should be included for analysis. Adjacent sectionsremoved from a wall, ceiling, door, window, implementhandle, and automobile door, fender, and hood are examples ofi
35、tems that can be valuable for assessing questioned and knownsample differences and evaluating the possible cross transfer oftrace materials.7.3.3 Paint flakes can be removed from the parent surface bya number of methods. These include but are not limited to thefollowing: lifting or prying loosely at
36、tached flakes, cuttingsamples of the entire paint layer structure using a clean knife orblade, or dislodging by gently impacting the opposite side ofthe painted surface. When cutting, it is important that the bladebe inserted down to the parent surface. It should be noted thatno one method of sampli
37、ng should be relied upon exclusively.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.E16100228. Procedure8.1 Discussions of forensic paint analysis are provided indated but detailed form by Crown (3), and more recently byNielsen (4), Thornton (5), Maeh
38、ly and Strmberg (6) andStoecklein (7).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 in Fig. 1 are numbered to correspond tothe discussions prese
39、nted 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 determining which techniques to use. Theforensic coatings ex
40、aminer 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 provide guid-ance for the selection of appropriate methods.8.3 Fig. 1 does not imply that o
41、ther examinations should beexcluded or that the order of the procedures in the chart isirrevocable. Samples that are neither constrained by amountnor condition should be subjected to analyses that will deter-mine the color and texture of the paint as well as the number,order, colors and textures of
42、the layers in a multi-layeredsample. In most cases, instrumental techniques should beemployed 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. Th
43、ese techniques shouldalso be selected to provide classification and/or componentidentification information to be used in significance assess-ments. For samples that are limited in layer structure complex-ity, techniques for the comparison of both the binder andpigment portion of the coating must be
44、used. The choice oftechniques may change depending upon sample characteristics.For instance, 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
45、-ray analysis(SEM-EDS), X-ray fluorescence (XRF) and X-ray diffractionFIG. 1 Scheme for Forensic Paint ExaminationsE1610023(XRD) may be used for identifying and comparing the pigmentportion of samples that exhibit a low pigment concentration.8.4 The flow-chart in Fig. 5is a guide to the determinatio
46、n ofthe possible origins of a motor vehicle paint in an investigativecase. It is usually possible to differentiate motor vehicle repaintfrom the original equipment manufacturer (OEM) paint bymicroscopical examination. If no OEM paint is present, thenonly the vehicle color can be reported. For OEM pa
47、int, thecolor of the topcoat layers and of the undercoat layers will eachbe useful in identifying manufacturer, model and year. Oftenthe two systems provide complementary information. In mostcases a range of possible makes/models/years will be generatedby the search. Further specific information can
48、 often bedeveloped through chemical analysis of the individual layers.Any of the techniques shown in Fig. 1 can be used, dependingon the databases available. Reference collections and databasesinclude books of color chips produced by automotive refinishpaint manufacturers for use by body shops and a
49、utomotiverepair facilities, manufacturer topcoat and undercoat color andchemical standards, “street” samples collected from damagedmotor vehicles, OEM information on paint formulations andcollections of infrared spectra or pyrograms of known paints.Examples of these include the Royal Canadian MountedPolice/Technical Working Group on Materials Analysis(RCMP/TWGMAT) database, the National Automotive PaintFile which is maintained by the Federal Bureau of Investiga-tion (FBI), the Collaborative Testing Services reference collec-tion of automotive paints and the Georgia Burea
