ASTM E1789-96
(Guide)Standard Guide for Writing Ink Identification
Standard Guide for Writing Ink Identification
SCOPE
1.1 This guide covers assisting forensic examiners in identifying writing inks. Included in this analysis scheme are the necessary tools and techniques which have been successfully utilized to reach conclusions as to the common or different origin of two samples of ink.
1.2 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.
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Designation: E 1789 – 96
Standard Guide for
Writing Ink Identification
This standard is issued under the fixed designation E 1789; 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 (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This guide is intended as a general outline for use in forensic ink examinations, where the intention
is to identify an ink formula or type. It is designed both for the experienced document examiner (see
Guide E 444) and for those unfamiliar with previously reported procedures. The aim is to describe
those techniques that will provide the most information about an ink with the least damage to the
document. This guide refers to well-reported and thoroughly tested techniques currently in use by
forensic document examiners, chemists, and other scientists.
Following the procedures as outlined, an examiner can accurately discriminate between ink
formulas; as well as significantly reducing the possibility of reporting false matches of ink samples
from different sources or incorrectly differentiating ink samples from a common source.
Identifications of ink formulas may be accomplished through the use of an adequate collection of
standards. The necessary completeness of a comparison collection and limitations of conclusions will
be addressed in the guide.
1. Scope E 1422 Guide for Test Methods for Forensic Writing Ink
Comparison
1.1 This guide covers assisting forensic examiners in iden-
2.2 NIST Standards:
tifying writing inks. Included in this analysis scheme are the
NBS Standard Sample No. 2106 ISCC-NBS Centroid Color
necessary tools and techniques which have been successfully
Charts
utilized to reach conclusions as to the common or different
NBS Special Pub. 440 Color: Universal Language and
origin of two samples of ink.
Dictionary of Names
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 Definitions—Terminology has been defined in Guide
priate safety and health practices and determine the applica-
E 1422, with the following addition:
bility of regulatory limitations prior to use.
3.1.1 ink library—an organized collection of reference
2. Referenced Documents samples of inks and related materials.
3.1.1.1 Discussion—For maximum effectiveness in identi-
2.1 ASTM Standards:
fication of questioned ink, an ink library should at minimum
D 1535 Test Method of Specifying Color by the Munsell
include the following elements: reference samples of ink in
System
3 unused form, either in bulk samples from the manufacturer or
E 131 Terminology Relating to Molecular Spectroscopy
in distribution form such as bottles, pens, or cartridges; dried
E 284 Terminology of Appearance
ink specimens of each reference sample of ink placed on paper
E 444 Guide to Descriptions of Scopes of Work Relating to
(scribble sheets); analysis results of each reference sample of
Forensic Sciences for Questioned Document Area
ink,forexample,TLCsheets/plates;andaninkinformationfile
for each reference sample of ink containing available relevant
This guide is under the jurisdiction of ASTM Committee E-30 on Forensic data. All elements of the collection should be as complete,
Sciences and is the direct responsibility of Subcommittee E30.02 on Questioned
Documents.
Current edition approved March 10, 1996. Published May 1996.
2 5
Annual Book of ASTM Standards, Vol 06.01. Available from U.S. Department of Commerce, National Bureau of Standards,
Annual Book of ASTM Standards, Vol 03.06. OfficeofStandardReferenceMaterials,R.B311,ChemistryBuilding,Gaithersburg,
Annual Book of ASTM Standards, Vol 14.02. MD 20899.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1789
comprehensive, and up-to-date as possible, although this will Densitometry, are sufficient to distinguish most inks, and
vary between ink libraries. therefore to match most questioned ink samples to a reference
sampleofinkorarelativelylimitedgroupofreferencesamples
4. Significance and Use
in an ink library.
4.3.1 Just as with other forensic tools, for example, FTIR,
4.1 The reasons for identifying writing inks are to obtain
GC, HPLC, etc., pattern profile matching with reference
information about: the origin; relative availability; distribution;
samples is often sufficient to yield an identification. Individual
and first and last (if applicable) production dates. It is this
component identification through an internal standard ap-
valuable information available from the manufacturer and
proach may be used, but is not usually necessary.
through the use of a collection of standards that differentiates
this guide from Guide E 1422.
5. Interferences
4.1.1 The procedure set forth in this guide are applicable in
determining the significance of a match obtained by perform-
5.1 Most interferences with ink examinations and subse-
ing the examinations set out in Guide E 1422 (by showing how
quent identifications are a result of variables interacting with
rare or common an ink formula may be), or in determining the
the ink. These variables can usually be attributed to the writing
source of an ink. The identification of a specific ink formula
processorstorageconditions,oracombinationthereof,andare
can facilitate the determination of the first date of production
discussed in Guide E 1422. Evaluation of these variables can
and the discontinuance date of that ink.
avoid problems examinations.
4.1.2 In addition to proficiency in the use of the necessary
5.2 Other interferences can be caused by changes to the
analytical procedures, specialized knowledge and experience
TLC diffusion of fluorescent components, differences in the
on the part of the examiner are required. Also required is a
paper controls, differences in color due to fading either of the
comprehensive collection of reference samples of ink and
inks or of the components on the TLC sheet/plate, solvent
related materials (ink library). The ink reference standards are
depletion, or a combination of these and other factors. Evalu-
cataloged, analyzed, and stored according to the procedures
ationofthesevariables,useofpaperblanks,andproperstorage
described in Section 7.
and maintenance of the reference samples and related material
4.2 Evenwithaccesstoacomprehensiveinklibrary,itisnot
in the ink library can avoid problems in examinations.
always possible to positively identify a questioned ink sample.
5.3 Large batch-to-batch variations in the manufacturing
This is because some ink formulations are very similar; usually
process can also lead to problems in evaluating a match.
only non-volatile ingredients such as dyes and pigments are
compared; and no matter how comprehensive the ink library is, 6. Reagents and Equipment
the collection will never be complete.
6.1 Appropriate reagents and equipment for the required
4.2.1 Some ink formulas are not distinguishable; they be-
techniques have been listed in Guide E 1422, with the follow-
have in the same manner under various examinations because
ing additions:
they have similar formulas with the same nonvolatile compo-
6.1.1 Low Resolution Precoated Plastic or Glass Sheets/
nents. Thus, it is not always possible to find a single reference
Plates of Silica Gel, without fluorescent indicator (60 angstrom
ink sample in the ink library that matches a questioned ink.
pore size).
Evenifoneisfound,itmaynotprovideanidentificationunless
NOTE 1—Low resolution sheets/plates are generally not as sensitive to
the ink formula is shown to be unique because it contains a
external effects, for example, temperature, humidity, and development
specific component. For these reasons, it will not be possible to
conditions. They have the quality of exhibiting excellent reproducibility
identify every questioned ink. There is not always a forensic
and as such are an appropriate choice for storage media of the ink library
answer to a question at hand.
TLC plates.
4.2.2 It must also be understood that it is not possible to
6.1.2 High Resolution Precoated Plastic or Glass Sheets/
create an all inclusive ink library, just as it would not be
Plates of Silica Gel, without fluorescent indicator (60 angstrom
possible to obtain every fingerprint, or every paint, soil, or
pore size).
glass sample. Conclusions as to the identity of an ink are
dependent on the completeness of the ink library used. Thus, it NOTE 2—It is recommended that the TLC sheets/plates be kept in a
desiccator.
is possible that there are one or more inks not in the ink library
that would be indistinguishable from the questioned ink.
7. Procedure
4.3 In spite of these limitations, questioned inks can be
7.1 Collection, Preparation, and Analysis of Reference Ma-
associated with reference ink samples with a high degree of
terials for the Ink Library:
confidence using the systematic approach in this guide. The
7.1.1 Reference Samples of Ink:
analytical procedures given here, such as TLC and TLC
7.1.1.1 The core of the ink library consists of reference
samples of ink formulas, usually obtained from ink manufac-
6 turers. Additionally, ink and pens should be purchased at
Brunelle, R. L. and Pro, M. J., “A Systematic Approach to Ink Identification,”
retailers on a regular basis (at least once a year), because it is
Journal of Offıcial Analytical Chemistry, Vol 55, 1972, pp. 823–826.
Brunelle, R. L. and Cantu, A. A., “Training Requirements and Ethical
not always possible to obtain samples directly from all manu-
Responsibilities of Forensic Scientists Performing Ink Dating Examinations,” Letter
facturers of ink. Because of international trade and travel
to the Editor, Journal of Forensic Sciences, November, 1987.
patterns, reference samples of ink should be obtained on a
Crown, D. A., Brunelle, R. L., and Cantu, A. A., “Parameters of Ballpoint Ink
Examination,” Journal of Forensic Sciences, Vol 21, 1976, pp. 917–922. world-wide basis.
E 1789
7.1.1.2 Accession information for each reference sample of undergo other changes sooner. Deteriorating TLC sheets/plates
ink should be recorded, such as date of acquisition, source, etc. should be replaced as needed.
For an assembly of reference samples of ink to be considered
7.1.4 Ink Information Files:
a collection rather than an accumulation, it must be organized
7.1.4.1 All available relevant data on each reference ink
and cataloged. If a computerized database is used, searching
sample should be collected and maintained. This can include
can be on any criteria; if not, the features noted in a light
information on the manufacturer; ink formula; manufacturer’s
examination performed in accordance with Guide E 1422 can
designation(s) and marketing name(s); other user’s (for ex-
be used to organize the collection.
ample, pen manufacturers) and their designation(s) and mar-
7.1.1.3 Reference samples of ink should be stored under
keting name(s); volume of ink manufactured; area(s) of distri-
optimal laboratory conditions (sealed containers, darkness,
bution; first production date; date first released to the public;
temperature and humidity controlled) to retard drying, oxida-
last production date; etc.
tion, and other changes related to aging.
NOTE 5—Some information may be considered proprietary by the ink
7.1.2 Dried Ink Specimens:
manufacturer or other source. Such information should be treated with the
7.1.2.1 Prepare a specimen by making lines or marks on a
appropriate confidentiality.
sheet of paper (scribble sheet). Record the date of preparation.
7.1.4.2 Analytical results and other data from 7.1.3 should
Allow the ink to dry for up to 1 h under ambient conditions
be maintained. Efficient organization of this information can
before storing.
facilitate searches of the ink library.
NOTE 3—Dried ink specimens can be effectively stored on filter type
7.2 Ink Identification—Ink identification is a two step pro-
paper that does not contain optical brightener additives. A sample of any
cess. The first step involves comparative analysis techniques
paper being considered for a library storage media should be analyzed
following the laboratory procedures as indicated in this standard.This will described in Guide E 1422. The second step includes compari-
determine if the paper will interfere with the examination procedure.
son of any resulting TLC plate from the initial analysis to an
ink library.
7.1.2.2 Dried ink specimens should be stored under optimal
7.2.1 Perform the light, ultraviolet (UV), and infrared (IR)
laboratory conditions (darkness, temperature and humidity
examinations and record results in accordance with Guide
controlled) to retard fading and other changes.
E 1422.
7.1.3 Results of Analysis of Reference Samples—Because
7.2.2 Perform the spot testing and solubility testing and
questioned ink samples will be analyzed in accordance with
record results in accordance with Guide E 1422.
Guide E 1422 for comparison with the ink library (see 7.2), the
reference samples in the library should undergo the same 7.2.3 Perform the thin layer chromatography TLC examina-
analyses with results preserved for future searching.
tion in accordance with Guide E 1422.
7.1.3.1 Perform the light, ultraviolet (UV), and infrared (IR)
7.2.3.1 The comparison reference inks in the ink library
examinations in accordance with Guide E 1422.
must have been extracted using the same solvent. If there is no
7.1.3.2 Perform the spot testing and solubility testing in
TLC plate in the ink library that meets this requirement,
accordance with Guide E 1422.
prepare one in accordance with Guide E 1422 using the
7.1.3.3 Perform the thin layer chromatography TLC exami- appropriate solvent before proceeding.
nation in accordance with Guide E 1422.
7.2.4 First TLC Interpretation:
7.1.3.3.1 Note and record the extraction solvent used.
7.2.4.1 Samples of ink with qualitatively different colorant
Where appropriate, prepare duplicate extractions using all the
compositions can be easily distinguished by comparison of the
different solvents likely to be employed in extraction from
characteristics described in Guide E 1422.
various substrata. Prepare a TLC of each extract, recording the
7.2.5 Comparison Against a Library of Standards:
solvent used. Appropriate TLC sheets/plates will then be
7.2.5.1 Where comparison against a library of standards is
available for comparison with questioned samples.
desired, the initial TLC analysis should be conducted on low
7.1.3.3.2 The TL
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