Art Forensics #7:
Forensic Science and Fine Art Authentication, 'La Bella Principessa'
by
John Daab Ph.D., for Fine Art Registry®
"La Bella Principessa" - A Case Study in Forensics
The Present Sighting
Originally identified by Christie's auction house in a 1990 catalogue as "German, 19th Century, Young Girl in Profile in Renaissance Dress", it has now been renamed, "La Bella Principessa" by Mark Kemp, a specialist Leonardo Da Vinci art historian. According to various news releases it is a genuine Da Vinci because a smudged fingerprint found on the painting revealed by a revolutionary multispectral analysis was "comparable" to a fingerprint on another Da Vinci work. The fingerprint match was determined by a self-proclaimed forensic art fingerprint expert to be "highly comparable." Others noted that there were "significant stylistic" consistencies.1
Recorded provenance of the painting shows that it was won at auction from Christie's by Kate Ganz in 1998 for $19,000. She sold it to Peter Silverman in 2007 for $19,000. Carbon dating and infrared analysis determined that it was from the 15th - 16th century. It is now said to be worth about 150 million dollars.2 No earlier history of the painting seems to be available.
A Brief History of Questionable Fine Art Sightings
Over the last few years there has been a spate of fine art sightings: the trucker's "Pollock": the "Pollock" from Long Island, New York: the Warhol double negation of authenticity.3 All have had issues and all have been relegated to the category of works of questionable authenticity. The Hahn Leonardo has been floating around for over one hundred years and still has not been accepted as authentic.3 The most recent discovery, "La Bella Principessa", a work alleged to have been created by Da Vinci in the 15th century has apparently satisfied stylistic considerations, and age via media analysis. Additionally a fingerprint examination by a Canadian self-proclaimed "art fraud detective and forensic expert" claimed to establish a match between a fingerprint discovered on this painting and a print on an earlier Da Vinci. This expert has been involved in other fingerprint examinations. The previous owner of the painting does not accept that her piece is a Da Vinci. The owner(s) of the Hahn Da Vinci spent their lives promoting the authenticity of their Da Vinci only to find that their engagement in this promotion provided no financial gain and resulted in a life of misery trying to convince the unbelievers.4 The past owner of "La Bella Principessa" seems to be taking the opposite stance, realizing that the big payoff via authenticity is not so easy. The present owner and diligent promoter of the most recent Leonardo find, notes that it is really not so unreasonable to assume that this might be the big score since there are thousands of Leonardos floating around.5 As a matter of fact, Michelangelo produced 4,000 works of which 10,000 reside in the USA. The fact that there is a Leonardo finger/palm print on the work makes it even more certain that the present one really is a true Leonardo. Or does it?
Forensics and Art Authentication
Forensic science, as it relates to fine art authenticity determinations, is grounded in a multitude of undertakings which are relevant to a work's authenticity.6 Determining the authenticity of a given work (by forensic methods) starts with scientific testing of the materials used to create that work. In the case of an oil painting, forensics will look at the medium used in the work - paint pigments, type of canvas, stretchers, canvas fastening devices such as nails, and so on. If any part of the materials fails to be from the correct era, the work automatically fails the authenticity test. A Home Depot barcode on the canvas of a supposed 15th century work would be a telltale of inauthenticity, as would a paint pigment manufactured years after the work was created. In the Center Art Gallery case it was established that Dali prints were forged since the print paper was manufactured after Dali stopped signing prints.7 While forensic material testing can be used to prove that a work of art is not authentic, the reverse is not true. The fact that the materials are all consistent with the supposed time period of creation of the work does not prove that the work was by a particular artist. The work must also pass forensic tests of signature, text and linguistic documentation or provenance, fingerprints, and expert determination, in addition to connoisseurial examination of artist style, brush stroke, content matter, and cultural identifiers. Finding a Ford Mustang in a supposed 15th century Dutch genre painting would be an instant disqualifier. In the present sighting of the uncovered "Da Vinci," the road to authenticity leaves much to be desired in terms of rigor of tests conducted to determine authenticity, and the assemblage of so called experts leading the push for authenticity.
The Identifiers of the New Find
Most if not all of the evidence provided to establish the authenticity of the new "Da Vinci" has emerged from news reporting agencies quoting alleged art experts and the basis for their conclusions. Readers have been regaled by a "significant match" of style, and a "highly comparable" consistency of fingerprint between the current smudged one and an existing fingerprint found on an earlier Da Vinci work.8 The fingerprint match was enabled by a new approach using multispectral science testing wavelength of materials unseen by the human eye. The individuals and organizations performing the testing and examination are self-proclaimed forensic art experts, agencies utilizing revolutionary forensic approaches in evidence gathering and scholars specialized in art history.9 More importantly, there is no second opinion in the fingerprint conclusion, a requirement following the forensic standard of ACE-V entailing analysis, comparison, evaluation and verification. The reasoning behind the conclusion of authenticity is that the carbon dating and infrared examination of the materials/media used conform with the media used in the 15th century; the match of style has to do with a match between how Da Vinci created the eyes, mouth, hair, and so on for his accepted authentic works. In point, one would not yell match between the portrait of the Principessa and a Warhol Marilyn Monroe. The current sighting is claimed to be authentic because the carbon 14 dating method determined that materials used in the current work correspond to the materials used in works made in the 15th century, the style of the work fits Da Vinci's style, and the fingerprint found on the work matches a fingerprint on an earlier Da Vinci work. In the fine art authentication process the experts have somewhat followed the typical paradigm to establish that the sighting is from the hand of the artist. The problem, however, is that what the alleged experts identify as the process falls short of the mark on many levels, starting with forensic examination.
The Application of Forensic Examination to Objects of Fine Art
Material Testing
The process of fine art authentication is founded upon scientific analysis of an object's media or the material make-up of a work, provenance or the documents supporting the authentication, and connoisseurship which focuses on culture, technology, style, subject matter, brush stroke, lighting, and so on. The forensic science part of the analysis consists of media/material testing, signature, questioned documents, fingerprinting, text and linguistic analysis, and expertness founded upon previous training/education or previous acceptance in a court of law.10 The logic of the examination starts with material testing of paint pigments, canvas, i.e. textile, wood, paper or vellum, stretchers, and mechanical fasteners to determine if the age of the materials used matches the period of the creation of the work. This is the most important examination, since if it fails the object, no further testing is necessary. Failure results when forensic testing reveals that the materials forming the object were made after the object was supposed to have been created. The necessary decision following the testing is that the object is not authentic. Further analysis then becomes unnecessary since the object is now logically inconsistent with authentic documentation and connoisseurial assertions of compatibility with style etc. Forensic science applies a label of inauthentic at this point. But the absence of such proof of inauthenticity it does not prove that the work is authentic. The material/media may be authentic but it does not follow that the work is authentic since documentation and connoisseurship are required to complete the analysis and propel the object toward authenticity. Forensic material testing may stop the process, but may never (at this point science has not reached the authenticity process completely), forward it to a conclusion of being authentic. Some examples of forensic material testing are:
Infrared reflectography focuses on the layers of painting and the sketch made by the use of carbon black or charcoal by the artist. The different layers or alterations of the work are known as pentimenti. The alterations tell us the extent of restoration, whether it is a copy, and the different materials used. The more pentimenti the more likely it is that the work is the prime version.
Wood's Light seeks to identify the different types of fluorescent matter in a work. Fluorescent matter emits radiation and the quantitative levels emitted link the work to a given time.
Microscopic analysis allows the viewer to see beneath the surface and identify the particles within the structure of the work. Particles or minute matter comprising the work have birth and death times: materials are created at a particular point in time, and die out from disuse, exhaustion (supply no longer available), or regulations outlawing their use. The pigment Verona Green was exhausted in 1930, yellow iron oxide (mars yellow) was created in the lab sometime in the 1920s, and the use of lead in paint was outlawed for the most part in the 1980s due to negative health consequences. The type of pigment used in a work tells us in what time frame the work was created or restored.
Carbon 14 tests age of a given compound by focusing on the quantity of C-14 material left as the compound decays through time. It is less reliable as the predictor of age closer to the present and beyond 60,000 years. In point, the accuracy and reliability of C-14 increases with age up to about 60,000 years and then like the bell shaped curve, begins to decrease. Less accuracy is associated with materials made early and after 60,000 years; more accuracy is associated with materials found in an area midpoint in the curve.11 The maximum deviation or inaccuracy occurs for materials 600-700 years old.12
The Art Expert
The current culture of expertise in art analysis considers that the connoisseur is the recognized expert to carry out an analysis and conclusions. This tradition has come under fire by the court system, particularly the case law emanating from IRS rulings concerning fine art donations, appraisals, and validity of such donations. The IRS has noted that the current processes are not acceptable where current experts fail to provide a rigorous level of scholarship in the presentations that are filed. Appraisers do not engage in authenticity examination for the most part, and the IRS finds this distressing since without authenticity, appraisals are meaningless. In point, connoisseur expertise rules the current system of art analysis while forensic science is operating as an unrecognized system in art authentication, although its structures process and resolve varying degrees of art issues.13
Provenance or Questioned Document Analysis
If forensic tests of materials or media reveal that their age is consistent with the time of the work, the forensic examiner looks to analyze the document trail of evidence supporting the chronological progress of the piece to the present. Here the examiner focuses on bills of sale, tax records, or collections, estate transfers, auction results, catalogues, exhibitions and so on. The examiner will also investigate those documents, in relation to writing and text on them, signatures, telltales for aging, behavior patterns, and linguistic use. The examination here looks to correlate such aspects with the work. Dated documents whose make-up materially contradicts the date or signatures of the artist which are inconsistent will be discarded as being inauthentic. Provenance documents which are inconsistent with the writer's language or behavior pattern will also be discarded, as in the recent Killian14 episode whereby the alleged writer's style and behavior and the technology used to print the text showed that the document was not written by Killian. Killian's use of language, the printing and his behavior of not using a typewriter or word processor contradicted the evidence provided.
Connoisseurship
Supported by the evidence that the media/materials of a given work are consistent with the supposed date of the work, and a document assemblage which corroborates the document and the writer of the document, the process enters the stage of non-forensic expert analysis. The connoisseur expert is called upon to examine the forensically established work in terms of cultural telltales, style of the artist, subject matter, content, use of lighting, and idiosyncratic points establishing artist creation. The expert entering at this stage would be someone experienced in the work of the artist and not someone with a generalist art background. If a work identified as Vermeer's was to be examined, the expert would use Vermeer exemplars to compare the work. In the examination, the expert would look at dress, the type of work such as genre, or portrait, if the standard maps, bowls, windows, and lighting contrasts are present along with individual features of eyes, nose, hand, and hair, and compare these points with the exemplar to be able to derive a conclusion about the authenticity of the work.15
The coming together of the three pillars of forensic material testing, questioned document consistency and connoisseurial confirmation concerning a given work enables one to derive a conclusion that a given work is authentic. Please note here that such conclusions are not cast in stone. New technologies and documentation may turn today's conclusion of authenticity into tomorrow's fake or changed attribution. Similarly, inauthentic works, or incorrectly attributed works may move into authentic or different attributions. The paradigm of science, provenance, and connoisseurship is the standard process allowing and driving authenticity determinations. Improper processing, skipping steps, or questionable evidence weakens the authenticity proclamation and places a work under an "Issue status," meaning that judgment on authenticity is suspended until further information is provided. The Hahn Leonardo exists in this present state and has so for about 100 years.
"La Bella Principessa" and its Problems
As was noted earlier, misattributions of work do take place. The recent work under question presents a case study of how works not only fail the authenticity paradigm but seem to be manipulated more than examined and analyzed. To begin with, the presentation of the new work does not follow a careful and rigorous study, but comes from public relations snippets found in the newspaper/TV world. Not that anyone expects any evidential rigor to form the structure of the articles provided, but the absence of almost any research about who, what, why and how the work progressed from a relatively insignificant 19th century Germanic attribution to celebrity status and enormous value leads one to question and challenge the new attribution of the work to Da Vinci. Further, the fact that the new buyer knew he had a winner is irrelevant when cast against Christie's auction house's attribution. How did Christie's miss this one if in fact they did?
Some Questions of Meaning
Aside from the PR hoopla, there are questions of meaning arising from the so-called testing and descriptive identifiers associated with the process. Note is made by the alleged forensic expert that the smudged fingerprint is highly comparable to the so-called genuine fingerprint found on an earlier Da Vinci work. Assuming for the moment that by the smudges, the expert means that there is overlapping of fingerprint point data, or that the lines, ridges, curls are not evident, it is unacceptable to use such a fingerprint. Forensic fingerprint practitioners have asserted that smudged fingerprints cannot be used in any comparison.16 Further, the expert makes a point of the fact that Da Vinci was known to handle his works "a lot" and the expert's conclusion is that from the handling it must be Da Vinci's print. To this one argues that although it is accepted that Da Vinci did handle his works - he had to handle some to create them - it certainly does not follow that he handled them a lot, and therefore his fingerprint must be on the work. Other questions raised are, what does it mean to state that "X" is highly comparable? To the "significant" stylistic consistencies one would ask what does it mean to say "significant" and what exactly were the styles compared? Were there 10, 15, 20, styles compared and what is the meaning of "significant"? I do not think that "significant" means "statistically significant" since the background of the expert was in Art History not quantitative analysis.
Forensic Testing
Forensic testing may provide an age to a given material to the point that one may argue that the work was not recently created. It is questionable that it can provide an unambiguous and certain time frame accurate to within a few years. Multispectral examination technology has assisted in the interpretation of ancient papyri such as those found at Herculaneum, by imaging the fragments in the infrared range (1000nm). Often the text on the documents appears to be as black ink on black paper to the naked eye. At 1000nm, the difference in light reflectivity makes the text clearly readable. It has also been used to image the Archimedes Palimpsest by imaging the parchment leaves in bandwidths from 365-870 nm and then using advanced digital image processing techniques to reveal the under text of Archimedes work. The fact that it is touted as a revolutionary approach implies that the approach is lacking standards and error rates for use as a scientific appendage or methodology. Further, merely because it is used in one domain does not necessarily legitimize its use in another domain. A vacuum cleaner works well picking up dirt on a rug; one would not assume that it could pick a pile of 3/8" stones on a roadway.
Provenance
The current object was originally purchased by Kate Ganz in 1998 for $19,000 from Christie's auction house. In 2007, Canadian Richard Silverman purchased it from her for $19,000. Forensic examination however focuses on such documents commonly known as "questioned documents"17 and analyzes them in terms of mechanical text technology, signature styles such as slant of writing, use of idiom or specific language, spelling, grammar, and word complexity all leading to an identification of where, when, how, and who developed a particular document. In the present Principessa very little documentation about the work is available. The lack of surrounding documentation does not bode well for authenticity since forgers such as Van Meegren, Myatt, Hebbron seize such works as opportunities to market their fakes.18 Lack of documentation goes a long way to prevent the discovery of a fake.
Connoisseurship
Historically, connoisseurship is taken to mean the ability to recognize a given fine art work as from the hand of a particular artist. Commonly labeled as the "connoisseur's eye", individuals possessing this ability argue that it is an innate propensity developed by associations with fine art academically and socially. Eugene Thaw, a recognized connoisseur has stated that it was the fact that while growing up and surrounded by great works of art his "eye" came into being. Thomas Hoving, the former director of the Metropolitan Museum of Art noted that his "eye" resulted from looking at patterns, or telltales of a given artist's oeuvre and being able to recognize such points in a particular work in terms of how he made the hands, face, ears and so on. Hoving looked for the elements of a given artist's style based on comparable authentic works of the artist.19 According to Kemp the present work is a Da Vinci because "significant" style matches were found to exist between the new find and other Da Vinci works. The problem here is that the expert does not delineate what exactly is a significant style. I am not sure if it is even possible to defend the use of significant as a modifier of an ambiguous term without a loss in clarity. Further, artists change styles, develop into better or worse artists and as such with each modification the notion of a given style loses its meaning since there are levels and gradations of it. In point, identifying the new find in terms of significant style is somewhat of an empty or meaningless statement. History has made it clear that connoisseurs and so-called art experts have been noteworthy in their ability to raise forged, misattributed or poorly restored works to high levels of unwarranted authenticity. Hoving noted that 40% of the museum works he was involved in investigating were inauthentic.20
Fingerprints of the Artist
The first rule of forensic fingerprint identification is that to be able to identify a match in fingerprinting, an exemplar print must exist and the questionable print must match it via the standards or quantity of points used for a match.21 The points of match are the accepted number used for a match in a given agency or organization. There are as many as 30 points (of recognition and identification) to a print and some agencies require 8 and others 15 of these points to be the same in the print as in the exemplar for the print to be considered a match. There are some who may argue that there are as many as 100. Most police forensic science departments accept the 8 to 15 point standard.22 There are additional requirements that the exemplar print is one which is certified as authentic in that a certified fingerprint agent or organization attests that the print was taken correctly and is the print of the individual in question. The person taking the prints must also follow certain standards established by Federal Rules of Evidence 702 and various regulations surrounding the taking and using such evidence in a court of law. Such laws, standards, and regulations serve to protect the innocent and provide documentation that a piece of evidence was processed correctly.23 Various court cases concretize the carrying out of correct procedures in fingerprint gathering and castigate those who attempt to circumvent the rules. The alleged art forensic expert who gathered the fingerprint connecting the new and old Da Vinci failed miserably in even following the most elementary of proper procedures in fingerprint taking. First, the use of an non-standard procedure, and virtually untested methodology - multispectral gathering - flies in the face of fingerprint evidence gathering processes. The lack of an established error rate for the new gathering technique lessens the print's reliability. The fact that no evidence or document trail exists to establish that the supposed exemplar print was from Da Vinci in the older work destroys any semblance of a comparable match. Whether or not the artist handled the earlier work a lot does not prove that the print on it - if there is a print on it - is from the artist. It could be from anyone who was around in his studio. Note also that paint takes many hours to dry and as a result provides greater opportunity for others to touch it and leave their fingerprints on it. And finally, as mentioned, there is no evidence of peer review of the self-proclaimed expert's findings by a recognized fingerprint expert.
The Forensic Art Expert
The concept of the forensic art expert is a misnomer in that there are no standards or schools providing a designation of forensic art expert. Historically, connoisseurs have been accepted as art experts. The problem with their expertise is that they are not always right, and how they arrive at their conclusions is often more hocus-pocus than sound logical and empirical reasoning. Having paintings sing to them or feeling something in their stomach as a process of establishing authenticity undermines their expert status. Case law is whittling away at the connoisseur merely making a call of authenticity without solid scholarship behind the call. Expert status in court requires the expert to have training, years of solid experience in his or her field, education, peer review and a publication record. Lacking this combination closes the door in a court of law. Looking at the alleged expertise of the individuals making the call about the Principessa being authentic we find that one has been identified by the Da Vinci society as definitely not a specialist in Da Vinci since Da Vinci has not been a prime focus of his studies.24 The other expert has no apparent CV establishing that he has any forensic educational or training background forging the expertise he claims. This expert is noted for presenting a digitally forged print as a genuine Pollock print.25
Conclusions
As far as a sighting or discovery of a new Da Vinci, it is argued that from a forensic point of view:
- Forensic testing conclusions of the materials making up the new Da Vinci by a new, untested and questionable error rate method/mechanism are empirically questionable, and potentially unsound.
- Using Carbon 14 analysis for a piece only 500-600 years old produces less accurate and more unreliable results, and as such cannot predict a particular age or small range of age within the period.
- The fact that provenance documentation is almost absent supporting the Da Vinci call leaves the work suspect in terms of who had it, where it came from, and when it was made.
- Matching the fingerprint of the present work with a comparable one is problematic since the exemplar used has no chain of custody. It is not even clear if the new print was taken correctly.
- In terms of matching styles between the new and exemplar works, the note of a significant connoisseurial match is unfounded due to questions of meaning, and obtuse terminology.
- The expertise promoted by the carriers of the new find is unwarranted since no evidence exists supporting the expertise and more importantly, evidence exists stating that one expert is definitely not a specialist in Da Vinci's work.
- Digital imaging of fingerprints has been noted to create unreliable images and smudged prints are unacceptable for comparison.
- The fundamental standard of processing a fingerprint ACE-V - analysis, comparison, evaluation and verification - was not followed leading to an assertion that the call of a match was deficient.
The above analysis draws the conclusion that the approaches, methods and standards used to confirm authenticity of the new Da Vinci did not support an authenticity conclusion. This does not mean that the work is inauthentic only that until more research takes place following acceptable standards, methods, and approaches, present assertions of authenticity are questionable.
- http://www.antiquestradegazette.com/news/7311.aspx
- http://www.cnn.com/2009/WORLD/europe/10/13/da.vinci.portrait.found/index.html
- http://www.timesonline.co.uk/tol/news/uk/article717330.ece
Brewer, John. The American Leonardo.
- Op Cit.
- http://news.discovery.com/history/da-vinci-painting.html
- Fine Art Registry Forensics
- http://www.ifar.org/case_summary.php?docid=1184707485
- http://www.antiquestradegazette.com/news/7311.aspx
- Op Cit.
- Daubert http://www.ourstolenfuture.org/press/2003/2003-0707-CEN-daubert.htm
- http://www.artandsciencehandbook.com/
- http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/cardat.html#c2
- http://www.latimes.com/news/local/la-me-irs2mar02,0,3015698.story
- http://wap.cbsnews.com/site?&index=1&sid=cbsnews&pid=sections.detail&storyId=643224
- http://www.fineartregistry.com/articles/art-education/fine-art-connoisseur.php
- http://www.officer.com/print/Law-Enforcement-Technology/DNA-from-Fingerprints/1$25197
- http://www.apsu.edu/oconnort/3210/3210lect08.htm
- http://www.artfakes.dk/famous.htm
- http://www.amazon.com/Master-Pieces-Curators-Thomas-Hoving/dp/0393328384
- http://www.fineartregistry.com/articles/art-education/fine-art-connoisseur.php
- http://www.onin.com/fp/
- http://www.latent-prints.com/Thornton.htm
- http://federalevidence.com/rules-of-evidence
- http://www.bbk.ac.uk/hosted/leonardo/
- http://www.newswiretoday.com/news/32498/
— by John Daab Ph.D.
| December 30, 2009
Print
|
View Article Archives
