forgery and forensics
This page considers forensics, ie determination of the
authenticity of objects (including documents and art works)
or the information that they embody.
It covers -
It is supplemented by a note on 'security
Determining the authenticity of an object reflects the
nature and provenance of that object: essentially what
questions can be asked about it and what questions can
Those questions encompass physical characteristics of
objects such as anachronisms in their composition, more
subjective matters such as information content or style,
and the context in which they are located. The unavailability
of substantive information about the history of many antiquities
in particular – their lack of provenance - and commercial
or curatorial imperatives to ignore uncertainties is a
Many forensic technologies will allow determination of
an object's age, with varying degrees of accuracy, but
necessarily will not tie an object from the requisite
period to a particular author.
preceding pages of this profile have suggested that
media, different objects, pose different challenges
or fraud is often underpinned by a willingness to believe
(the complicity of victims and authenticators or other
acceptability of 'unexceptional' items embodies assessments
about risk and value
is often very good at providing evidence of falsification
but poor at conclusively proving authenticity.
much of history authentication has been a matter of connoisseurship
rather than science, with experts relying on intuition
(often based on immersion in an author or visual artist's
oeuvre), personal idiosyncrasies or minute physical examination
to identify discrepancies such as unnaturally regular
cracquelure in oil paintings or the tell-tale absence
of staining and signs of wear in bound documents.
One rival of art guru Berenson was thus famed for smelling
and licking paintings, not unreasonable when the paint
on some 'old masters' was barely dry.
More recently a dealer in Cycladic sculptures is quoted
the object between thumb and forefinger and strike it
lightly on a doorsill, like a tuning fork. A forgery
will emit a clear bell-like ring, whereas a genuine
idol emits a dull thump. It is, of course, necessary
to experiment with both genuine and imitation idols
in order to accustom one's ear to the proper sound
is only in the past fifty years that authentication has
moved out of the library and into the laboratory, although
particular figures emphasis intangibles such as 'nose'
or 'intuition' (which is presumably restricted an attribute
of the individual).
In discussing document forgery James Gilreath commented
are some individuals who claim to have what could only
be said to be astonishing confidence in their abilities
to detect authenticity. In The Hitler Diaries
Charles Hamilton boasts that his 'feel test'
can distinguish between a genuine and forged document
in "two or three seconds" or by inspecting
only a "half dozen words". Hamilton on at
least one occasion before the publication of The
Hitler Diaries described his 'feel test'
in his Retail Catalogue A (1984). The first
step is to hold the document upside down in order to
get a better feel for the writing. As I have written
elsewhere, it would be better to hold the document right
side up and stand on your head for health purposes in
order to gain at least some benefit from this procedure.
draw problematical conclusions from data gathered through
high tech tools, with claims in 2006 for example that
identifying Leonardo da Vinci's left index fingerprint
"could help provide information on such matters as
the food the artist ate and whether his mother was of
principles, context and provenance
As the preceding paragraphs and pages have suggested,
forensic examination has two aspects, looking for attributes
demonstrate that the item cannot be authentic (eg because
it uses an anachronistic technology or features anachronistic
information, such as South American fauna in a mediaeval
artwork) - exclusionary attributes
ii) associate the item with a particular creator/owner
(eg features an authentic signature) - inclusionary
have been various attempts to reduce forensics to a set
of principles. The Bollandist Abbe Mabillon,
founder with Lorenzo Valla of the science of diplomatics
(ie critical analysis and verification of documents),
for example suggested in his 1681 De Re Diplomatica
that a document (and by extension other entities) embodied
a system of external and internal elements comprising
ie the determining cause of the document's creation
individuals who concur in its formation
procedures through which acts are carried out
documentary form that binds the elements together
of original order (respect des fonds) and provenance -
differentiating between documents within a functional-structural
context and those in isolation (innately less trustworthy,
more difficult to authenticate and more likely to be a
forgery) - articulated by Mabillon's successors offered
both a forensic tool and a mechanism for assessing risk.
That is important since, as we have highlighted in considering
questions of electronic authentication and identity,
on a day to day basis the need to authenticate persons,
personas, items and transactions varies widely. It is
not necessary to provide full personal authentication
when buying a single carton of milk or using a concession
pass on public transport. Other transactions, such as
purchase of a $50 million art work, require a greater
degree of certainty.
Recognition of a principle of 'best fit' have been reflected
in enactments such as Australia's federal Evidence
Act and Canada's 1998 Uniform Electronic Evidence
Act. They avoid the radical skepticism exemplified
by Mabillon's contemporary Jean Hardouin, responsible
for the 1697 suggestion that most classical texts were
forgeries generated by 13th century monks under the direction
of Severus Archontius. It has been echoed by contemporary
assert that video footage of the moon landings is a clumsy
forgery from a Hollywood back lot.
As a point of entry for documentation see in Trusting
Records: Legal, Historical and Diplomatic Perspectives
(Dordrecht: Kluwer Academic 2000) by Heather MacNeil and
Scientific Examination of Questioned Documents (Lanham:
Rowman & Littlefield 1992) by Ordway Hilton. MacNeil
pays tribute to landmark conceptual works such as Muller,
Feith & Fruin's 1898 Manual for the Arrangement
& Description of Archives.
There is more technical analysis in Kenneth Rendell’s
Forging History: the Detection of Fake Letters &
Documents (Norman: Uni of Oklahoma Press 1994), Katherine
Koppenhaver's Forensic Document Examination: Principles
and Practice (Totowa: Humana Press 2007) and Joe
Nickell's Detecting Forgery: Forensic Investigation
of Documents (Lexington: Uni Press of Kentucky 1996).
Questions about contemporary and historical diplomatics
are explored in Luciana Duranti's Diplomatics: New
Uses for An Old Science (Lanham: Scarecrow Press
1998), Charles Hamilton's Great Forgers & Famous
Fakes: The Manuscript Forgers of America & How They
Duped the Experts (New York: Crown 1980) and David
Gracy's 'What You Get Is Not What You See: Forgery &
the Corruption of Recordkeeping Systems' in Archives
& the Public Good: Accountability & Records in
Modern Society (Westport: Greenwood 2002) edited
by Richard Cox & David Wallace. Duranti collaborated
with Terry Eastwood and Heather MacNeil in Preservation
of the Integrity of Electronic Records (Dordrecht:
Kluwer 2002). Gordon Rugg explores the controversial Voynich
An introduction to art forensics is provided by Otto Kurz's
classic Art Forgeries & How To Examine Paintings
Scientifically, his Fakes (New York: Dover
1967), Stuart Fleming's Authenticity in Art: The Scientific
Detection of Forgery (New York: Crane 1976), Roger
Marijnissen's Paintings: genuine, fraud, fake: modern
methods of examining paintings (Brussels: Elsevier
1985) and Fakebusters (Chicago: SPIE/McCrone
Research Institute 1999) edited by Walter McCrone &
Richard Weiss. Joe Nickell's Camera Clues: A Handbook
for Photographic Investigation (Lexington: Uni Press
of Kentucky 1994) considers photographic forgery and forensics.
Forensic technologies essentially aim to exclude rather
than include and deal with two aspects –
exclude the object by identifying anomalies in its physical
properties (eg that a 'renaissance' painting includes
a pigment not invented until the 1950s or that a 'George
Washington' letter is on paper with a watermark
first used in 1856)
provide additional information for an assessment of
style or content (eg indicate that the materials used
in a work are authentic but that there is an anomaly
in the content or other attributes)
technologies are non-destructive or non-invasive; others
involve damage to the object.
The pigments and inks used by artists and writers broadly
reflect the technology available at the time and have
thus changed over the centuries (eg from inks based on
soot and oak-tree gall to those based on petrochemicals).
Laboratory analysis of the pigment can provide an indication
of an item's age.
Chemical analysis of paper, canvas or other bearers may
also provide indications of a document or graphic work's
age. Paper from different eras may for example use grass,
linen or timber fibre treated with chemicals or coated
with a size that contains whiteners such as titanium and
can be detected through chemical analysis in a laboratory.
More prosaically, 'counterfeit-detection pens' used in
detection of forged bank notes use an 'ink' that turns
gold if the note's paper has the characteristics of genuine
paper and turns black if those characteristics are absent.
There is a lucid introduction in The Scientific Examination
of Documents: Methods and Techniques (London: Taylor
& Francis 1997) by David Ellen.
X-ray (eg x-ray diffraction, infrared microspectroscopy,
x-ray photoelectron spectroscopy and x-ray fluorescence)
technology can be used to identify the composition of
an object or reveal particular features, such as areas
of repair or an image that has been over-painted. X-ray
analysis has gained popular attention as a tool in the
authentication of Old Master paintings, with the technology
revealing recent paintings underneath supposed older works,
and computer axial tomography offering three-dimensional
views of sculptures. It is sometimes accompanied by ultraviolet
and infrared examination.
Newer tools such as magnetic resonance imaging (MRI) have
increasingly been used in non-destructive viewing inside
wooden sculptures, ceramics and bronzes to determine anomalous
repair or construction features. Starting points include
Paul Mix's Introduction to Nondestructive Testing:
A Training Guide (New York: Interscience 1987) and
Radiography of Cultural Material (London: Butterworth-Heinemann
2005) by Andrew Middleton & Janet Lang.
Dendrochronology involves dating wooden objects (in particular
sculpture and paintings on wooden panels by examination
of tree rings. Although dendrochronology registers are
now widely available (allowing timber to be dated to a
specific year), use is inhibited by requirements that
an adequate number of rings be available for examination.
A useful introduction is Tree Rings: Basics &
Applications of Dendrochronology (Dordrecht: Kluwer
Academic 1989) by Fritz Schweingruber.
Atomic Absorption Spectrophotometry and Inductively-coupled
Plasma Spectrometry testing reflects the unique spectral
signatures of chemical compositions. Burning of a small
sample of a pigment, textile or ceramic glaze can be used
to identify its composition and thus determine whether
anomalous compounds are present in a work.
Radiocarbon dating employs measurement of the amount of
radiocarbon left in an organic object. Radiocarbon, a
radioactive form of carbon, is absorbed by animals and
plants, decaying at a steady rate once the organism dies.
The dating is broadly accurate for objects less than 10,000
years old. Radiocarbon dating of the Vinland Map for example
has placed the parchment at around 1434. Testing of the
pigment in 1972 suggested that the map was made after
1917; proton-induced X-ray analysis in 1987 indicated
that the titanium content of the pigment was far less
than in 1972 tests by Walter McCrone and that the map
might thus predate 1917.
Stable Isotope Analysis uses examination of isotopes to
map stone sculpture to individual quarries, with instances
of supposed Cycladic statues being found to come from
quarries in the US or Scandinavia.
An introduction is provided by Robert Taylor's Radiocarbon
Dating: An Archaeological Perspective (London: Academic
Thermoluminescence, another tool in the examination of
ceramics, is based on measurement of light produced when
a sample of the object is heated, based on its absorption
of cosmic radiation. In principle, the older a work, the
greater the thermoluminescence. Test results may be skewed
by previous x-ray examination.
Handwriting analysis involves examination of script, ie
individual symbols and words. Typically it is based on
a close comparison of a questioned document with one of
accepted authenticity (eg recognised provenance), with
analysts looking for at unique characteristics in the
way that letters are formed and the ligatures between
It has been criticised as a very inexact science - or,
unsurprisingly given claims that analysts can provide
fortune-teller style insights into the "secrets of
life, love and destiny", as a pseudo-science - and
received little recognition by courts in most jurisdictions.
Defenders comment that some high-profile failures, such
as the 1980s Kujau 'Hitler Diaries', were attributable
to the lack of valid control documents (ie one forgery
was being compared with another, rather than a genuine
Points of entry into the literature are Forensic Handwriting
Identification: Fundamental Concepts and Principles
(New York: Academic Press 2000) by Ron Morris and Questioned
Documents: A Lawyer's Handbook (New York: Academic
Press 2000) by Jay Levinson.
Textual analysis, pioneered by figures such as Malone
and German biblical scholars, uses statistical and other
tools in the identification of vocabularies and semantic
structures to identify whether a questioned text has the
same characteristics as those of one with known authorship.
It forms the basis of work about the authorship of some
Renaissance literature (eg did Shakespeare write particular
plays), in examination of contemporary works such as Primary
Colours and – more problematically –
in claims about automated determination of the gender
of authors of academic papers and email.
Some of the more accessible studies about stylometrics
are Computation into Criticism: A Study of Jane Austen's
Novels and an Experiment in Method (Oxford: Clarendon
Press 1987) by John Burrows, Inference & Disputed
Authorship: The Federalist (Reading: Addison-Wesley
1964) by Frederick Mosteller & David Wallace, Analysing
for Authorship (Cardiff: Uni of Wales Press 1996)
by Jill Farringdon, Vina Tirvengadum's study
of the Romain Gary hoax, Joseph Rudman's 2002 overview
Non-Traditional Authorship Attribution Studies in
18th Century Literature: Stylistics, Statistics &
the Computer and Don Foster's Author Unknown
: On The Trail of Anonymous (New York: Holt 2000).
Much handwriting and signature analysis uses stereo microscopes,
which provide examiners with a three-dimensional view
of ink striations, pen movement and other details. Document
examiners often use a video spectral comparator - a digital
imaging system that subjects documents to a variety of
wavelengths from infrared through ultraviolet - because
some inks will become visible and others disappear under
different wavelengths, due to differences in chemical