ASTM E1610-02(2008)
(Guide)Standard Guide for Forensic Paint Analysis and Comparison
Standard Guide for Forensic Paint Analysis and Comparison
SIGNIFICANCE AND USE
The guide is designed to assist the forensic paint examiner in selecting and organizing an analytical scheme for identifying and comparing paints and coatings. The size and condition of the sample(s) will influence the selected analytical scheme.
SCOPE
1.1 Forensic paint analyses and comparisons are typically distinguished by sample size that precludes the application of many standard industrial paint analysis procedures or protocols. The forensic paint examiner must address concerns such as the issues of a case or investigation, sample size, complexity and condition, environmental effects, and collection methods. These factors require that the forensic paint examiner choose test methods, sample preparation schemes, test sequence, and degree of sample alteration 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 intended to assist individuals who conduct forensic paint analyses in their evaluation, selection, and application of tests that may be of value to their investigations. This guide describes methods to develop discriminatory information using an efficient and reasonable order of testing. The need for validated methods and quality assurance guidelines is also addressed. This document is not intended as a detailed methods description or rigid scheme for the analysis and comparison of paints, but as a guide to the strengths and limitations of each analytical method. The goal is to provide a consistent approach to forensic paint analysis.
1.3 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 standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.
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Designation: E1610 − 02(Reapproved 2008)
Standard Guide for
Forensic Paint Analysis and Comparison
This standard is issued under the fixed designation E1610; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 Forensic paint analyses and comparisons are typically 2.1 ASTM Standards:
distinguished by sample size that precludes the application of D16TerminologyforPaint,RelatedCoatings,Materials,and
many standard industrial paint analysis procedures or proto- Applications
cols. The forensic paint examiner must address concerns such D1535PracticeforSpecifyingColorbytheMunsellSystem
astheissuesofacaseorinvestigation,samplesize,complexity E308PracticeforComputingtheColorsofObjectsbyUsing
and condition, environmental effects, and collection methods. the CIE System
These factors require that the forensic paint examiner choose E1492Practice for Receiving, Documenting, Storing, and
test methods, sample preparation schemes, test sequence, and Retrieving Evidence in a Forensic Science Laboratory
degree of sample alteration and consumption that are suitable
3. Terminology
to each specific case.
3.1 Definitions—For definitions of terms used in this guide
1.2 This guide is intended as an introduction to standard
other than those listed in 3.2, see Terminology D16.
guides for forensic examination of paints and coatings. It is
3.2 Definitions of Terms Specific to This Standard:
intended to assist individuals who conduct forensic paint
3.2.1 additive (modifier)—any substance added in a small
analyses in their evaluation, selection, and application of tests
quantity to improve properties. Additives may include sub-
that may be of value to their investigations. This guide
stances such as dryers, corrosion inhibitors, catalysts, ultravio-
describesmethodstodevelopdiscriminatoryinformationusing
let absorbers, plasticizers, etc.
an efficient and reasonable order of testing. The need for
validated methods and quality assurance guidelines is also
3.2.2 binder—a non-volatile portion of a paint which serves
addressed.Thisdocumentisnotintendedasadetailedmethods
to bind or cement the pigment particles together.
description or rigid scheme for the analysis and comparison of
3.2.3 coating—a generic term for paint, lacquer, enamel, or
paints, but as a guide to the strengths and limitations of each
other liquid or liquifiable material which is converted to a
analyticalmethod.Thegoalistoprovideaconsistentapproach
solid, protective and/or decorative film after application.
to forensic paint analysis.
3.2.4 discriminate—to distinguish between two samples
1.3 Some of the methods discussed in this guide involve the
based on significant differences; to differentiate.
use of dangerous chemicals, temperatures, and radiation
3.2.5 discriminating power—the ability of an analytical
sources. This guide does not purport to address the possible
procedure to distinguish between two items of different origin.
safety hazards or precautions associated with its application.
This standard does not purport to address all of the safety 3.2.6 known sample—a coating sample of established ori-
gin.
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
3.2.7 paint—commonly known as a pigmented coating (see
health practices and determine the applicability of regulatory
3.2.3).
requirements prior to use.
3.2.8 pigment—a finely ground, inorganic or organic,
insoluble, dispersed particle. Besides color, a pigment may
This guide is under the jurisdiction of ASTM Committee E30 on Forensic
Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2008. Published July 2008. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1994. Last previous edition approved in 2002 as E1610–02. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E1610-02R08. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1610 − 02 (2008)
provide many of the essential properties of paint, such as which are selected, based on their potential for use in evalu-
opacity,hardness,durabilityandcorrosionresistance.Theterm ating and/or discriminating the samples of interest.
pigment includes extenders.
6. Significance and Use
3.2.9 questioned sample—a coating sample whose original
source is unknown.
6.1 The guide is designed to assist the forensic paint
examiner in selecting and organizing an analytical scheme for
3.2.10 significant difference—a difference between two
identifying and comparing paints and coatings. The size and
samples that indicates that the two samples do not have a
conditionofthesample(s)willinfluencetheselectedanalytical
common origin.
scheme.
4. Quality Assurance Considerations
7. Collection of Suitable Samples
4.1 Aqualityassuranceprogrammustbeusedtoensurethat
analytical testing procedures and reporting of results are
7.1 The potential for physical matches between known and
monitored by means of proficiency tests and technical audits.
questioned samples must be considered before selecting the
General quality assurance guidelines may be found in “Trace
method of paint sample collection. Care should be taken to
Evidence Quality Assurance Guidelines” (1).
preserve the potential for a physical match.
7.2 Questioned Samples:
5. Summary of Practice
7.2.1 Questioned samples should include all loose or trans-
5.1 Paint films are characterized by a number of physical
ferred paint materials. Sources of questioned samples can
and chemical features. The physical characteristics may in-
include tools, floors, walls, glass fragments, hair, fingernails,
clude color, layer sequence and thickness, surface and layer
roadways, adjacent structures, transfers or smears on vehicles,
features, contaminants and weathering. Chemical components
ortransferstoorfromindividualssuchasdamagedfabricwith
mayincludepigments,polymers,additivesandsolvents.These
paint inclusions.Whenever possible, items with paint transfers
features can be determined and evaluated by a variety of
should be appropriately packaged and submitted in their
macroscopical, microscopical, chemical, and instrumental
entirety for examination. If sampling is necessary, the proce-
methods.Limitedsamplesizeandsamplepreservationrequire-
dures listed in “Trace Evidence Recovery Guidelines” (2) may
ments mandate that these methods be selected and applied in a
be used. When paint evidence is recognized, every effort
reasonable sequence to maximize the discriminating power of
shouldbemadetomanuallyremoveitbeforeusingtapeliftsto
the analytical scheme.
collect other types of evidence. If paint is collected with tape
5.2 Searching for differences between questioned and lifts,oneshouldbeawareofthepossibledifficultyencountered
whenattemptingtomanipulatepaintsamplesbearingadhesive
knownsamplesisthebasicthrustofforensicpaintanalysisand
residues. In addition, components of the adhesive could con-
comparison. However, differences in appearance, layer se-
taminate the paint sample and change its apparent chemistry.
quence, size, shape, thickness, or some other physical or
chemicalfeaturecanexisteveninsamplesthatareknowntobe 7.2.2 Smearedtransferscanexhibitminglingofcomponents
from several layers or films that could preclude application of
from the same source. A forensic paint examiner’s goal is to
assess the significance of any observed differences. The ab- some of the analytical methods discussed in this guide. Due to
the difficulties associated with collecting smeared or abraded
senceofsignificantdifferencesattheconclusionofananalysis
suggests that the paint samples could have a common origin. samples, the entire object bearing the questioned paint should
be submitted to the laboratory whenever possible.
The strength of such an interpretation is a function of the type
and/or number of corresponding features. 7.2.3 When contact between two coated surfaces is indi-
cated, the possibility of cross-transfers must be considered.
5.3 An important aspect of forensic paint analysis is the
Therefore, if available, samples from both surfaces should be
identification of the possible makes, models and years of
collected.
manufactureofmotorvehiclesfrompaintcollectedatthescene
of a crime or accident. The color comparison and chemical
7.3 Known Samples:
analysis of both the undercoat and top coat systems requires a
7.3.1 Whenfeasible,knownpaintsamplesmustbecollected
knowledge of paint formulations and processes, collections of
from areas as close as possible to, but not within, the point(s)
paint standards, and databases of color and compositional
of damage or transfer. These damaged areas are usually not
information.
suitable sources of known samples. The collected known
samples should contain all layers of the undamaged paint film.
5.4 The test procedure selected in a paint analysis and
Substantial variations in thickness and layer sequences over
comparison begins with thorough sample documentation.
short distances can exist across a painted surface. This is
Some features of that documentation are described in Practice
particularly true in architectural paint and for automotive films
E1492.Analysisgenerallybeginswithappropriatenondestruc-
where the curves, corners, and edges are often impact points
tive tests. If these initial tests are inconclusive or not exclu-
and may have been subjected to previous damage, sanding or
sionary, the examination may proceed with additional tests,
over-painting. If necessary, several known paint samples
should be taken to properly represent all damaged areas.
Known paint samples collected from different areas should be
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. packaged separately and labeled appropriately.
E1610 − 02 (2008)
7.3.2 When possible, the surface underlying the suspected 8.2 Areasonable scheme for forensic paint examinations is
transferareashouldbeincludedforanalysis.Adjacentsections outlined in Figs. 1-4. Potentially useful techniques for the
removed from a wall, ceiling, door, window, implement
discrimination of paint binders, pigments, and additives are
handle,andautomobiledoor,fender,andhoodareexamplesof
listed.ThemajorstepsinFig.1arenumberedtocorrespondto
items that can be valuable for assessing questioned and known
the discussions presented in this guide (for example 8.8,
sampledifferencesandevaluatingthepossiblecrosstransferof
Solvent Tests). For any given comparison, not all the tech-
trace materials.
niqueslistedinthesameareainFig.1arenecessarilyrequired.
7.3.3 Paintflakescanberemovedfromtheparentsurfaceby
Sample size, condition and layer structure complexity should
a number of methods. These include but are not limited to the
be considered when determining which techniques to use. The
following: lifting or prying loosely attached flakes, cutting
forensiccoatingsexaminershouldalwaysusethemorespecific
samplesoftheentirepaintlayerstructureusingacleanknifeor
and least destructive tests prior to those that require more
blade, or dislodging by gently impacting the opposite side of
sample preparation or consumption. A review of the general
thepaintedsurface.Whencutting,itisimportantthattheblade
technique descriptions, listed in 8.8-8.15, will provide guid-
be inserted down to the parent surface. It should be noted that
ance for the selection of appropriate methods.
no one method of sampling should be relied upon exclusively.
8.3 Fig. 1 does not imply that other examinations should be
8. Procedure
excluded or that the order of the procedures in the chart is
irrevocable. Samples that are neither constrained by amount
8.1 Discussions of forensic paint analysis are provided in
dated but detailed form by Crown (3), and more recently by nor condition should be subjected to analyses that will deter-
Nielsen (4), Thornton (5), Maehly and Strömberg (6) and mine the color and texture of the paint as well as the number,
Stoecklein (7). order, colors and textures of the layers in a multi-layered
FIG. 1 Scheme for Forensic Paint Examinations
E1610 − 02 (2008)
FIG. 2 Scheme for Forensic Paint Examinations
E1610 − 02 (2008)
FIG. 3 Scheme for Forensic Paint Examinations
FIG. 4 Scheme for Forensic Paint Examinations
sample. In most cases, instrumental techniques should be provide discrimination between as many types of paints and
employedtoanalyzeandcompareboththepigmentandbinder coatings as possible, should be used. These techniques should
portions of the sample. A combination of techniques, which also be selected to provide classification and/or component
E1610 − 02 (2008)
identification information to be used in significance assess- only the vehicle color can be reported. For OEM paint, the
ments.Forsamplesthatarelimitedinlayerstructurecomplex- colorofthetopcoatlayersandoftheundercoatlayerswilleach
ity, techniques for the comparison of both the binder and
be useful in identifying manufacturer, model and year. Often
pigment portion of the coating must be used. The choice of
the two systems provide complementary information. In most
techniquesmaychangedependinguponsamplecharacteristics.
casesarangeofpossiblemakes/models/yearswillbegenerated
For instance, pyrolysis-gas chromatography (PGC) may be
by the search. Further specific information can often be
utilized for identifying and comparing the binder portion of
developed through chemical analysis of the individual layers.
samples that exhibit a low binder concentration. Likewise,
Any of the techniques shown in Fig. 1 can be used, depending
scanningelectronmicroscopy-energydispersiveX-rayanalysis
onthedatabasesavailable.Referencecollectionsanddatabases
(SEM-EDS), X-ray fluorescence (XRF) and X-ray diffraction
include books of color chips produced by automotive refinish
(XRD)maybeusedforidentifyingandcomparingthepigment
paint manufacturers for use by body shops and automotive
portion of samples that exhibit a low pigment concentration.
repair facilities, manufacturer topcoat and undercoat color and
chemical standards, “street” samples collected from damaged
8.4 The flow-chart
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation:E1610–95 (Reapproved 2001) Designation:E1610–02 (Reapproved 2008)
Standard Guide for
Forensic Paint Analysis and Comparison
This standard is issued under the fixed designation E 1610; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Forensic paint sample analyses and comparisons are typically distinguished by a limited amount
sample that precludes the application of standard industrial paint analysis procedures or protocols to
these analyses. The issues before a case or investigation, sequence of events at the scene in question,
sample size, complexity and condition, environmental effects, and collection methods generally force
acriminalisttoaddresstheissuesoftestchoice,samplepreparationscheme,testsequence,anddegree
of sample alteration and consumption that are efficacious to each specific case as well as the interests
of all parties to a litigation.
1. Scope
1.1Thisguideisintendedtoassistindividualsandlaboratoriesthatconductforensicpaintanalysesintheirselection,application,
and evaluation of tests that can be of value to their investigation. It is not intended as a detailed methods description or protocol
for the analysis and comparison of paints but as a guide to a reasonable order for testing and to the strengths, limitations, and
possiblepitfallsofeachofavarietyofpotentiallyusefulanalyticalmethods.Numerousdetailedmaterialsareavailablethatdiscuss
each method, and selected references are noted as appropriate.
1.2This guide is intended for application to the analysis of industrial and commercially prepared paints and related coatings. It
does not propose to address the unique requirements of artistic, historical, or restorative paint analysis, although some of the
methods discussed herein may be applied to those fields.
1.1 Forensic paint analyses and comparisons are typically distinguished by sample size that precludes the application of many
standard industrial paint analysis procedures or protocols. The forensic paint examiner must address concerns such as the issues
of a case or investigation, sample size, complexity and condition, environmental effects, and collection methods. These factors
require that the forensic paint examiner choose test methods, sample preparation schemes, test sequence, and degree of sample
alteration 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 intended
toassistindividualswhoconductforensicpaintanalysesintheirevaluation,selection,andapplicationofteststhatmaybeofvalue
to their investigations.This guide describes methods to develop discriminatory information using an efficient and reasonable order
of testing. The need for validated methods and quality assurance guidelines is also addressed. This document is not intended as
a detailed methods description or rigid scheme for the analysis and comparison of paints, but as a guide to the strengths and
limitations of each analytical method. The goal is to provide a consistent approach to forensic paint analysis.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use. 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 standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the
user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements
prior to use.
2. Referenced Documents
2.1 ASTM Standards:
This guide is under the jurisdiction of ASTM Committee E30 on Forensic Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.
Current edition approved March 15, 1995. Published September 1995. Originally published as E1610–94. Last previous edition E1610–94.
Current edition approved April 1, 2008. Published July 2008. Originally approved in 1994. Last previous edition approved in 2002 as E 1610 – 02.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 06.01.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E1610–02 (2008)
D 16Terminology for Paint, Related Coatings, Materials, and Applications Practice for Application of Hose Stream
D 1535Practice for Specifying Color by the Munsell System Practice for Application of Hose Stream
D2244Test Method for Calculation of Color Differences from Instrumentally Measured Color Coordinates
D3168Practice for Qualitative Identification of Polymers in Emulsion Paints
D4764Test Method for Determination by X-Ray Fluorescence Spectroscopy of Titanium Dioxide Content in Paint
E105Practice for Probability Sampling of Materials
E141Practice for Acceptance of Evidence Based on the Results of Probability Sampling
E275Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near —Infrared Spectrophotometers
E 308Test Method for Computing the Colors of Objects by Using the CIE System
Practice for Application of Hose Stream
E334Practices for General Techniques of Infrared Microanalysis
E380Practice for Use of the International System of Units (SI) : the Modernized Metric System
E805Practice for Identification of Instrumental Methods of Color or Color-Difference, Measurement of Materials
E860Practice for Examining and Testing Items that Are or May Become Involved in Products Liability Litigation
E1360Practice for Specifying Color by Using the Optical Society of America Uniform Color Scales System
E 1492Practice for Receiving, Documenting, Storing, and Retrieving Evidence in a Forensic Science Laboratory
E1508Guide for Quantitative Analysis by Energy-Dispersive Spectroscopy Practice for Application of Hose Stream
3. Terminology
3.1Definitions—For definitions of terms used in this guide, see Terminology D16
3.1 Definitions—For definitions of terms used in this guide other than those listed in 3.2, see Terminology D 16.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 discriminate—to distinguish between two samples based on differences; to differentiate. additive (modifier)—any
substance added in a small quantity to improve properties.Additives may include substances such as dryers, corrosion inhibitors,
catalysts, ultraviolet absorbers, plasticizers, etc.
3.2.2 discriminating power—the measure of an analytical procedure is the ability to distinguish between two items of different
origin.
3.2.3known, , adj—an item of established origin. binder—a non-volatile portion of a paint which serves to bind or cement the
pigment particles together.
3.2.3 coating—a generic term for paint, lacquer, enamel, or other liquid or liquifiable material which is converted to a solid,
protective and/or decorative film after application.
3.2.4 questioned,,adj—forthepurposeofclassification.discriminate—todistinguishbetweentwosamplesbasedonsignificant
differences; to differentiate.
3.2.5 discriminating power—the ability of an analytical procedure to distinguish between two items of different origin.
3.2.6 known sample—a coating sample of established origin.
3.2.7 paint—commonly known as a pigmented coating (see 3.2.3).
3.2.8 pigment—a finely ground, inorganic or organic, insoluble, dispersed particle. Besides color, a pigment may provide many
of the essential properties of paint, such as opacity, hardness, durability and corrosion resistance. The term pigment includes
extenders.
3.2.9 questioned sample—a coating sample whose original source is unknown.
3.2.10 significant difference—a difference between two samples that establishes different origins for the two samples. —a
difference between two samples that indicates that the two samples do not have a common origin.
4. Summary of Practice
4.1Paint films are characterized by a number of physical and chemical features such as the following: color, surface texture,
contamination, and weathering; striae due to wear, impact, application techniques, or underlying surface irregularities; and paint
layeringorderandthickness,presenceofpigmentsordyes,orboth,andvehiclesorresinsandmodifiersinthepaint.Thesefeatures
can be determined and evaluated by a variety of visual, macro and microscopical, chemical, and instrumental methods. Limited
sample size and sample preservation requirements dictate that these methods be selected and applied in a reasonable sequence in
order to maximize the discriminating power of the test results.
4.2Searching for significant differences between samples is the objective of forensic paint analysis and comparison. Differences
almost always exist between samples. A forensic paint analyst’s goal is to demonstrate which differences are significant. The
absence of significant differences at the conclusion of an analysis is taken as evidence of common origin. The likelihood of
common origin between specimens is a function of a number of factors, including the following: the type or number, or both, of
matching features; the type of components in the paint film; the presence or absence of studies quantifying the uniqueness of these
components; and the discriminating power of the test methods used.
4.3The test procedure selected in a paint analysis and comparison generally begins with careful sample documentation. Some
features of that documentation are described in Practices E380, E860, and E1492. This documentation is usually followed by the
development of an evidence sampling plan. Such plans are discussed in Practices E105 and E141. Although these practices are
E1610–02 (2008)
directed toward industrial and consumer product sampling environments, they offer some insight into the legal expectations in
evidence sampling.Analysis generally proceeds with the simplest nondestructive tests available for the conditions of the case once
samplingandspecimendocumentationarecomplete.Iftheseinitialtestsdonotdiscriminatebetweenthesamples,theexamination
will continue with other tests that can require an increasing degree of sample preparation or consumption and are selected based
on the sample availability, and tests’ potential for discriminating the samples.
5.Significance and Use
5.1The guide is designed to assist in selecting and organizing an analytical scheme for identifying and comparing industrial,
architectural, or automotive paint films.
5.2The techniques discussed are generally applicable to films with layers >20 µm in thickness and for the identification of
pigment elemental components of Z > 6, elemental concentrations of >1%, and paint vehicle components in excess of 5% by
weight. These constraints are imposed by microscopical, infrared absorbance and energy dispersive X-ray analysis system
constraints.
6.Test Specimens
6.1Suitable Known Specimens:
6.1.1Known paint specimens should be collected from areas immediately adjacent to the point, or points, of transfer. The point
of impact or pressure transfer typically exhibits bare substrate or substrate with a damaged paint film. The collected known
specimensshouldcontainallpaintlayersoftheundamagedpaintfilm.Paintlayerscanbeginandendaswellasexhibitsubstantial
variations in thickness over short distances across a painted surface. This is particularly true in automotive and architectural paint
films at curves, corners, and edges, which are often impact or fulcrum points that may have been subject to previous damage,
sanding, or overpainting.
6.1.2The substrate or parent surface underlying the suspected transfer area should be included in the sample collected when
possible.Adjacent sections of wallboard, ceiling portions, door and window frames, implement handles, doors, fenders, hoods, or
entireautomobilesareexamplesofitemsthatcanbevaluable.Afewminutesofcomparativeworkwiththeparentsurface(s)might
resolve the questions in a case and save considerable time spent on other forms of laboratory analysis.
6.1.3Simple scraping may not provide suitable materials for definitive comparison. Paint flakes containing all layers can be
removed from the parent surface by a number of methods, including deformation by impact to the opposite side of the surface,
by lifting particles already separated from the surface but still retained at one edge or prying up fragments using a tool that does
not contaminate. It is important that the blade be inserted down to or adjacent to the parent surface and the paint popped from the
surface with the latter technique.
6.2Suitable Questioned Specimens:
6.2.1Questioned specimens should include all loose or transferred paint material available at the scene in question. The scene
can include such items as tools, floors, walls, glass fragments, hair, fingernails, a roadway, adjacent structures, transfers or smears
on vehicles, or transfers to or from individuals such as damaged fabric with paint inclusions and fibers or fabric impressions on
painted surfaces. Items with paint transfers should be packaged and submitted in their entirety for examination whenever possible,
ratherthanattemptingtoremovepaintfromasubstrateinthefield.Representativeorpartialsamplingcanreduceoreveneliminate
the possibility of a conclusive comparison or physical match to known materials.
6.2.2Flasks of whole paint films or films still attached to a substrate, such as a painted piece of wood or metal, provide the most
useful questioned samples for analysis. Fragments of films that do not represent the complete layering structure of the original
surface obviously offer fewer characteristics for comparison but can be useful in physical fits and other examinations.
6.2.3Smeared or abrasively transferred samples are generally more difficult to analyze but m
...
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