1、Designation: E 1610 02 (Reapproved 2008)Standard 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.
2、 A number in 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 typicallydistinguished by sample size that precludes the application ofmany standard ind
3、ustrial paint analysis 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 metho
4、ds, sample preparation 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 forens
5、ic paintanalyses 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 i
6、s alsoaddressed. 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 m
7、ethods 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, asso
8、ciated 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,and A
9、pplicationsD 1535 Practice for Specifying Color by the Munsell Sys-temE 308 Practice for Computing the Colors of Objects byUsing the CIE SystemE 1492 Practice for Receiving, Documenting, Storing, andRetrieving Evidence in a Forensic Science Laboratory3. Terminology3.1 DefinitionsFor definitions of t
10、erms used in this guideother than those listed 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 dryers, corrosion inhibitors, catalysts, ultr
11、avio-let absorbers, 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 f
12、ilm after application.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.
13、3.2.7 paintcommonly 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 termpigmen
14、t 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.1This guide is under the jurisdiction of ASTM Committee E30 on ForensicSciences and
15、 is the direct responsibility of Subcommittee E30.01 on Criminalistics.Current edition approved April 1, 2008. Published July 2008. Originallyapproved in 1994. Last previous edition approved in 2002 as E 1610 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cus
16、tomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Quality Assurance Consideration
17、s4.1 Aquality assurance 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 Pract
18、ice5.1 Paint films are characterized by a number of physicaland chemical features. The physical characteristics may in-clude color, layer sequence and thickness, surface and layerfeatures, contaminants and weathering. Chemical componentsmay include pigments, polymers, additives and solvents. Thesefe
19、atures can be determined 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 analy
20、tical scheme.5.2 Searching for differences between questioned andknown samples is the basic thrust of forensic paint analysis andcomparison. However, differences in appearance, layer se-quence, size, shape, thickness, or some other physical orchemical feature can exist even in samples that are known
21、 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 conclusion of an analysissuggests that the paint samples could have a common origin.The strength of such an interpretation is a functio
22、n 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 ofmanufacture of motor vehicles from paint collected at the sceneof a crime or accident. The color comparison and chemicalanalysis of b
23、oth the undercoat and top coat systems requires aknowledge of paint formulations and processes, collections ofpaint standards, and databases of color and compositionalinformation.5.4 The test procedure selected in a paint analysis andcomparison begins with thorough sample documentation.Some features
24、 of that documentation are described in PracticeE 1492. Analysis generally begins with appropriate nonde-structive tests. If these initial tests are inconclusive or notexclusionary, the examination may proceed with additionaltests, which are selected, based on their potential for use inevaluating an
25、d/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 scheme foridentifying and comparing paints and coatings. The size andcondition of the sample(s) will influence the selected anal
26、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
27、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
28、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
29、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-
30、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
31、radedsamples, 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-cated, the possibility of cross-transfers must be considered.Therefore, if available, samples from both surfaces should becollect
32、ed.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 damaged areas are usually notsuitable sources of known samples. The collected knownsamples should contain all layers of the unda
33、maged 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 filmswhere the curves, corners, and edges are often impact pointsand may have been subjected to previous
34、 damage, sanding orover-painting. If necessary, several known paint samplesshould be taken to properly represent all damaged areas.Known paint samples collected from different areas should bepackaged separately and labeled appropriately.7.3.2 When possible, the surface underlying the suspectedtransf
35、er area should be included for analysis. Adjacent sectionsremoved from a wall, ceiling, door, window, implementhandle, and automobile door, fender, and hood are examples ofitems that can be valuable for assessing questioned and knownsample differences and evaluating the possible cross transfer oftra
36、ce 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 attached flakes, cuttingsamples of the entire paint layer structure using a clean knife or3The boldface numbers in parentheses re
37、fer to the list of references at the end ofthis standard.E 1610 02 (2008)2blade, 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 sampling should be r
38、elied upon exclusively.8. Procedure8.1 Discussions of forensic paint analysis are provided indated but detailed form by Crown (3), and more recently byNielsen (4), Thornton (5), Maehly and Strmberg (6) andStoecklein (7).8.2 A reasonable scheme for forensic paint examinations isoutlined in Figs. 1-4.
39、 Potentially useful techniques for thediscrimination of paint binders, pigments, and additives arelisted. The major steps 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 sa
40、me area in Fig. 1 are necessarily required.Sample size, condition and layer structure complexity shouldbe considered when determining which techniques to use. Theforensic coatings examiner should always use the more specificand least destructive tests prior to those that require moresample preparati
41、on 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 other examinations should beexcluded or that the order of the procedures in the chart isirrevocable. Samples that are n
42、either 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 the layers in a multi-layeredsample. In most cases, instrumental techniques should beemployed to analyze and compare b
43、oth 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 componentidentification information to be used
44、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 used. The choice oftechniques may change depending upon sample characteristics.For instance, pyrolysis-gas chromatogra
45、phy (PGC) may beutilized for identifying and comparing the binder portion ofsamples that exhibit a low binder concentration. Likewise,FIG. 1 Scheme for Forensic Paint ExaminationsE 1610 02 (2008)3FIG. 2 Scheme for Forensic Paint ExaminationsE 1610 02 (2008)4scanning electron microscopy-energy disper
46、sive X-ray analysis(SEM-EDS), X-ray fluorescence (XRF) and X-ray diffraction(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. 5 is a guide to the determinationof the possible origins of a motor vehicle pa
47、int in an investi-gative case. It is usually possible to differentiate motor vehiclerepaint from the original equipment manufacturer (OEM) paintFIG. 3 Scheme for Forensic Paint ExaminationsFIG. 4 Scheme for Forensic Paint ExaminationsE 1610 02 (2008)5by microscopical examination. If no OEM paint is
48、present, thenonly the vehicle color can be reported. For OEM paint, 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 w
49、ill be generatedby the search. Further specific information can 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 automotiverepair facilities, manufacturer topcoat and undercoat color andchemical standards, “street” samples collected from damagedmotor vehicles, OEM information on paint formulations andcollections of infr
