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Subject: Fingerprints as an attribution tool

Fingerprints as an attribution tool

From: Anthony D. Ayers <raphaelmad>
Date: Thursday, April 8, 2004
We have become accustomed to the use of scientific methods to assist
in the attribution process, some of which have only recently been
introduced. Dendrochronology has certainly been helpful to the
Northern schools (although of little use to Italians). The advances
in infrared reflectography have been helpful to many, although
access to the more advanced equipment has been rather difficult for
independent researchers.  Advances in pigment analysis should
eventually allow us to do more than merely determine a timeframe
from whence an artwork comes.  X-rays, canvas studies, etc. have all
proven helpful to the art historian.

Regrettably there is one proven scientific method that has yet to be
embraced by the art historical community, that being fingerprint
analysis. There have been the occasional articles noting the
presence of fingerprints in artworks being examined (typically
during a conservation process) but little has been done beyond their
identification and photographing.

One of the reasons for the slow emergence of the use of fingerprints
by art historians is the difficulty of locating and lifting prints
from many media, particularly relatively smooth paint surfaces
(where strong raking light from specific directions, and often
multiple directions is required along with digital manipulation to
remove the visual distractions on the image caused by brush strokes
and craquelure) and on 3D work where the print is often distorted
(particularly in the cases where clay or wax has been pulled into
shape with the fingertips).

Admirably, a group of historians (in London?) are currently
examining all of the known works (autograph and questionable) of
Leonardo for fingerprints in the hopes that they can resolve some of
the attributions shrouded in uncertainty.  Perhaps the genesis of
this project was the discovery of fingerprints in the Ginevra di
Benci (NGA Washington) while examining it under infrared light.

It should not be a question of whether or not fingerprints should be
admissible as evidence (the admissibility issue has been tested for
over a hundred years by the highest level courts around the world)
but rather how can art historians and conservators use the material
in the attribution of an artwork. As with other scientific methods,
art historians and conservators need to educate themselves on how
the data may be used, and establish guidelines.

This forum offers such a broad spectrum of the community that it
would be a good place to address these issues.  Following are a few
thoughts to start off what I hope is a lively thread of discussion
including references, experiences and ideas. This message has been
cross posted to the CAAH bulletin board, if you cross post to
another please e-mail me any replies/comments.

I would be particularly grateful to anyone that can lead me to any
known fingerprints of Raphael!

It would seem reasonable that any fingerprints used as source data
for comparison should come from the original surface (paint, clay,
etc.) of undisputed autograph works by the master done without the
assistance of students.  In the case of modern artists there may
also be fingerprints on file with their respective governments,
perhaps from military service, arrest records, etc. that would also
be considered definitive.

In the vast majority of cases the lack of a match to the known
fingerprints of a master would not be cause for excluding the work
from being that of the master, particularly in old masters, because
the source data will in all likelihood only represent a portion of
the masters prints.  Even in the case of modern masters, where
fingerprints have been found on file, the impressions left in the
works surface could be from an area not normally printed, such as
the side of the hand, palm or for that matter a toe.

The level of attribution where a positive match to the source
fingerprints of the master has been found should be autograph.

When source fingerprints come only from items within the master's
studio, such as paint brushes, paint tubes, easels, etc. any work
found matching those prints could only be identified as being from
the studio of.

What techniques have people used to successfully locate
fingerprints, either deliberately or accidentally?

Once located, what techniques have been most successful in producing
a visual image of a fingerprint (please specify the media upon which
the print was found).  I have had some success with a high
resolution scan of a panel painting, although the results were
limited by the fact that the light was not coming in from a low
aspect angle (raking light) which would have facilitated
highlighting of the ridges.  The direction of the lighting has
proven to be one of the most critical factors, and the greatest
success has been when the fingerprint ridge lines run in a direction
perpendicular to the craquelure and the brush strokes.

Laser scanning at a very high resolution should prove to be a
terribly effective technique, has anyone tried this?  The resulting
3-D image could have varied digital light sources applied to
accentuate the fingerprint ridge structure to aid in identification.

Has anyone had success locating a fingerprint under the paint
surface (such as in a ground layer) through x-rays, infrared or
other techniques?

Anthony Ayers
Independent historian
Winnetka, IL

                  Conservation DistList Instance 17:65
                  Distributed: Thursday, April 8, 2004
                       Message Id: cdl-17-65-017
Received on Thursday, 8 April, 2004

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