Introduction Mona Lisa - American Bar Association

Mona Lisa Inside the Painting
Abrams, New York, 2006
CONTENTS
Preface, by Henri Loyrette
The Mona Lisa: Subtle Materials for a Subtle Effect, by Cécile Scailliérez
Explorations "at the Heart of the Mona Lisa", by Jean-Pierre Mohen, Michel Menu, et Bruno Mottin
The Practical Sequence of the Study, by Bruno Mottin
Chapter I From the Royal Apartments to the Laboratory: The History of the Painting
by Nathalie Volle, Geneviève Aitken, Daniel Jaunard, Béatrice Lauwick, Patrick
Mandron, and Jean-Paul Rioux
Early Restorations to the Painting
The Earliest Scientific Studies and Commissioned Restorations
Exhibitions at the Louvre and Loans Abroad
Chapter II : The Poplar Panel
The Mona Lisa’s Wooden Support, by Élisabeth Ravaud
The Complex System of Fine Cracks, by Élisabeth Ravaud
Measuring the Relief of the Panel Support without Contact, by Fabrice Brémand, Pascal Doumalin,
Jean-Christophe Dupré, Franck Hesser, and Valéry Valle
Physical and Mechanical Characterization of the Support, by Luca Uzielli, Paolo Dionisi Vici, and
Joseph Gril
Simulation of the Effects of Ambient Variations, by Patrick Perré, Romain Rémond, and Joseph Gril
Mechanical Modeling of the Activity of the Flexible Frame, by David Dureisseix, Joseph Gril, and
Olivier Arnould
Chapter III :The Painting: Image and Material
The Preparation of the Panel, by Élisabeth Martin
The Painter's Palette, by Élisabeth Martin, in collaboration with Régina da Costa Pinto Dias Moreira,
and Jean-Paul Rioux
A Reading of the Image, by Bruno Mottin
The Traces of Time, by Bruno Mottin, Jean-Paul Rioux, and Regina da Costa Pinto Dias Moreira
Close Observation, byJean-Paul Rioux
Photographic Imaging, by Elsa Lambert
X-rays, by Élisabeth Ravaud
Analysis of the Paint Layer, by Éric Laval, Sandrine Pagès-Camagna, and Philippe Walter
The Spectrophotometric Approach to Color, by Guillaume Dupuis
Chapter IV : From the Real Image to the Virtual Image
Examination of the Mona Lisa by High-Resolution 3-D Imaging, by John Taylor, François Blais, Luc
Cournoyer, Michel Picard, Louis Borgeat, Guy Godin, J.-Angelo Beraldin, Christian Lahanier, and
Marc Rioux
Colorimetric Analysis through Multispectral Digitization, by Christian Lahanier
Imagery in High Definition: A Prelinary Synthesis, by Christian Lahanier
Conclusion : The Mona Lisa, Leonardo da Vinci, and the Visitor: An Exceptional Encounter, by Jean-
Pierre Mohen, Michel Menu, and Bruno Mottin
Select Bibliography

The Authors
Jean-Pierre Mohen, General Curator, Director of the Centre de Recherche et de Restauration des
Musées de France (C2RMF) from 1994 to 2005, and of the UMR 171-CNRS
Michel Menu, Senior Scientist, Head of the Research Department, C2RMF
Bruno Mottin, Curator, Research Department, C2RMF
Geneviève Aitken, Documentalist, Documentation Department, C2RMF
Olivier Arnould, Lecturer, Mechanics and Civil Engineering Laboratory, UMR 5508-CNRS, University of
Montpellier-II
J-Angelo Beraldin, Senior Scientist, Visual Information Technology, NRC, Ottawa
François Blais, Senior Scientist, Visual Information Technology, NRC, Ottawa
Louis Borgeat, Scientist, Visual Information Technology, NRC, Ottawa
Fabrice Brémand, University Professor, Mechanics of Solids Laboratory, UMR 6610-CNRS, University of
Poitiers
Regina da Costa Pinto Dias Moreira, Painting Restorer
Luc Cournoyer, Technical Officer, Visual Information Technology, NRC, Ottawa
Paolo Dionisi Vici, Ph. D., Dipartimento di Scienze e Tecnologie Ambientali Forestali, University of Florence
Pascal Doumalin, Lecturer , Mechanics of Solids Laboratory, UMR 6610-CNRS, University of Poitiers
Jean-Christophe Dupré, Senior Scientist, CNRS, Mechanics of Solids Laboratory, UMR 6610-CNRS, University
of Poitiers
Guillaume Dupuis, Ph. D., Research Assistant, C2RMF-University of Versailles
David Dureisseix, University Professor, Mechanics and Civil Engineering Laboratory, UMR 5508-CNRS,
University of Montpellier-II
Guy Godin, Senior Scientist, Visual Information Technology, NRC, Ottawa
Joseph Gril, Senior Scientist, Mechanics and Civil Engineering Laboratory, UMR 5508 -CNRS, University of
Montpellier-II
Franck Hesser, Scientist, Mechanics of Solids Laboratory, UMR 6610-CNRS, University of Poitiers
Daniel Jaunard, Painting Restorer, wood support
Christian Lahanier, Senior Scientist, Head of the Documentation Department, C2RMF
Elsa Lambert, Photographer, Research Department, C2RMF
Béatrice Lauwick, Documentalist, Restoration Department, C2RMF
Éric Laval, Scientist, Research Department, C2RMF
Patrick Mandron, Painting Restorer, wood support
Élisabeth Martin, Senior Scientist, Conservation and Restoration Department, C2RMF
Sandrine Pagès-Camagna, Scientist, Research Department, C2RMF
Patrick Perré, University Professor,Director of the Laboratory for Studies and Research on Wood as a Material,
UMR ENGREF INRA, University of Nancy I
Michel Picard, Technical Officer, Visual Information Technology, NRC, Ottawa
Romain Rémond, Ph. D., Laboratory for Studies and Research on Wood as a Material, UMR ENGREF, INRA,
University of Nancy I
Marc Rioux, Scientist, Visual Information Technology, NRC, Ottawa
Jean-Paul Rioux, Honorary Senior Scientist, Research Department, C2RMF
Élisabeth Ravaud, Senior Scientist, Research Department, C2RMF
Cécile Scailliérez, Head Curator, Paintings Department, Musée du Louvre
John Taylor, Senior Scientist, Visual Information Technology, NRC, Ottawa
Luca Uzielli, University Professor, Dipartimento di Scienze e Tecnologie Ambientali Forestali, University of
Florence
Valéry Valle, Lecturer , Mechanics of Solids Laboratory, UMR 6610-CNRS, University of Poitiers
Nathalie Volle, Head Curator, Department of Conservation and Restoration, C2RMF
Philippe Walter, Senior Scientist, CNRS, Research Department, C2RMF

Explorations at the Heart of the Mona Lisa
The challenge we set ourselves was to study the Mona Lisa without touching it, using nondestructive
methods involving no contact with the painting. The success of the enterprise depended on a
number of cutting-edge technologies, which we brought together for this very special task. We did not
consider it appropriate at this point to carry out a microsample to test, for example, to avoid
disturbances in the layers of the painting's protective varnish.
It was important to carry out these studies of the Mona Lisa at the time when its display case
was being changed, in order to complete the dossier on the work using new methodological approaches
which have proved highly effective in recent years, and which were likely in particular to provide
answers to certain questions relating to the specifications for the new display case's temperature and
humidity controls. We also aimed to make a visual evaluation of the painting which would enable it to
be presented in the best possible way by choosing, for example, the correct intensity, color temperature,
and direction of lighting. In addition, this was an opportunity to make a much closer examination of the
interior of the support, the pictorial layer, and the protective varnish, and to try to gain a better
understanding of what makes this famous painting a unique masterpiece.
With this research, and with the observations and studies brought together in this publication,
the Mona Lisa is now by far the best-documented painting in the Louvre. Because of this we did suffer
at times from a lack of cross-reference in the comparative approaches that we would have liked to adopt,
since even the other paintings by the master have not been subjected to comparable studies. As a result
there was a risk of over-interpretation, of which we needed to be constantly aware. In particular it was
essential to ensure that we exercised caution at all times in our attempts to interpret the artist's
intentions.
It very quickly became apparent that each of the various analytical methods used provided
information that was specific, but which also revealed facets of the work as a whole. This meant that we
would need to make extra efforts to link each result to others that had already been obtained, or were
expected to be. For instance, the relationship between colors could not depend solely on their
juxtaposition, but also on a specific connection between two colors, such as those of the flesh tints and
hair, with subtleties of transition (sfumato) that were intended by the artist.
Much of our attention was taken up with a different type of problem, that of changes that have
taken place over time, including ones that are barely perceptible. The painting is in good condition, but
nevertheless the effects of ageing can be seen in certain colors such as the blues of the sky and the
greens of the landscape, and a slight yellowing of the successive layers of varnish on the surface. In
these circumstances, we always viewed the "Leonardo da Vinci palette" not as the one that the painter
held in his hand, but as the set of colors that have come through to us from it, mixed, brought into play
by glazes, and sometimes aged or yellowed.
The initial approach we adopted was historical; we put together a collection, including some
very fine new discoveries, of the written and photographic archives of the Mona Lisa painting itself
since its creation.
When the painting was taken to the French Center for Museum Research and Restoration
(C2RMF) laboratory, we were primarily concerned with a material approach whose many original
aspects will be described in detail later on. The aim here was to study the wooden support and assess its
internal movements, however imperceptible, and their consequences for the preparatory layer, the
painted layer, and the varnish. Measurements were taken, very precise observations were recorded, and
by calculations and graphic representations we were able to arrive at a modelization of the warping in
the panel in accordance with the variations in its environmental conditions. The conclusions we drew
from this modelization are reassuring for the panel's future.
One of the original aspects of this dossier is the approach developed from scientific imaging
techniques. We were already familiar with radiography and infrared photographs of paintings, but not
with emissiography, which produces excellent results. Other new techniques are multispectral and

microtopographical imaging. Important results have already been achieved, and it is likely that these
approaches will also give rise to innovative ideas concerning Leonardo’s other paintings, drawings, and
writings.
Following on from this reflection, we wanted to reconsider the definitive aesthetic choice that Leonardo
da Vinci made in order to convey the subtleties of artistic creation. With the scholarly distance this book
allows us, we have tried to identify the role played by the sensibility of Mona Lisa's gaze and smile in a
vision that is typical of the Renaissance, where the artist is inspired by divine grace.
If there is a strong connection between the paradisiacal woman in the painting and the genius
who painted her, there is also a similar relationship between the painting itself and the visitor; the work
actually produces a strange kind of rapture which is part of its greatness. From the museographical point
of view, this means that attention needs to be paid to the painting's visibility and surroundings, and to
providing access for the visitor to all the approaches opened up by laboratory research to many aspects
of the painting which are not visible on the surface, but are nevertheless very real.
« Hostinato rigore » or"Obstinate rigor" was Leonardo's motto, and it underlies all the observations and
conclusions that we have drawn from our study of the Mona Lisa. The general impression of this work,
which was "altered time and time again" and was never finished (as is shown by an area of the
landscape to the left of the figure) was expressed by the English art historian Kenneth Clark, when he
said that the sitter, Mona Lisa, was as inaccessible as a "submarine goddess.” 1 Clark was going back to
the poetic image created in the Romantic era, when Théophile Gautier compared her to an "Isis of a
cryptic religion," but his metaphor also stressed the way in which the work was exhibited: in a glass
case which, while carefully protecting the painting from possible attack by museum visitors, tended to
keep them at an unbridgeable distance from it.
Vasari, who was the first writer to refer to the painting, reported that "it was painted in such a
manner as to make every valiant craftsman, be he who he may, tremble and lose heart.” 2 We know that
Vasari could not have seen the work himself and knew about it only by hearsay, but nevertheless his
lyrical description, given shortly after Leonardo finished the painting, is also a critical analysis of a
painting by a painter, containing minuscule details which could only have been perceived by having a
close, familiar, and prolonged relationship with the work. Kenneth Clark makes the point that the Mona
Lisa's glass box prevents the viewer from really seeing the young Italian woman painted by Leonardo
over a long period, from around 1503─04 to 1513─14.
Clark's metaphor suggests that the Mona Lisa's box is like an aquarium, and that the viewer cannot
rediscover the "warm life" in the "submarine goddess of the Louvre." For him, the thick glass which has
protected the painting since it was stolen from 1911 to 1913 and attacked with a stone in 1956 creates
the impression of a "diver in deep seas," whereas seen from closer up the work reveals a complexion
with "the delicacy of a new-laid egg." 3 One of many other commentators on the Mona Lisa was Walter
Pater, who in 1869 wrote that the Mona Lisa "is expressive of what in the ways of a thousand years men
had come to desire… She is older than the rocks among which she sits." It may seem that after so much
has been said about the painting, "one can no longer look at the Mona Lisa today as anything other than
an image.” 4
One can try to gain access to the painting, "to the image," in a less specifically iconological
way, by studying the painting's construction in terms of perspective. This was a matter to which, as we
know, the painter devoted a vast amount of passionate and scientific effort, working not just on the
geometric perspective but on others as well: "the aerial perspective, the perspective of colors, shadows,
and losses, that is to say the loss of perception.” 5 From this point of view, the work of art is a
manifestation of the ways in which the real can be represented, a medium of expression for a way of
thinking which Daniel Arasse describes as non-verbal, since "through its materials (those of painting),
its forms, there is something that thinks.” 6
On the subject of painting, Leonardo wrote: "Oh marvelous science, you keep alive the fleeting
beauties of mortals, and give them more permanence than the works of nature, continually altered by
time which inevitably leads to old age! And such a science keeps the same proportion with divine nature
as its works do with the works of nature.” 7

Kenneth Clark stresses how inextricably linked Leonardo's scientific research was with his
painting: "although Leonardo's approach [to these sciences of nature: geology, botany, meteorology…]
has become more scientific, he still sees with a painter's eye… At every stage Leonardo's research,
however austere, was fused with the texture of his imagination.” 8
Another way of approaching the work is, as Cécile Scailliérez suggests, to remain as close as
possible to its materiality in order to understand the "marvelous science" of the painter. The painting has
been studied and analysed several times in the laboratory, and each examination has benefited from
advances in scientific method, especially in the field of photography, which on each occasion has shown
itself to be a powerful scientific tool. We shall see in the first chapter that every laboratory study has
coincided with an unusual event in the work's history: an accident, a theft, an exhibition, or a change in
presentation. The most recent event is a change in the Mona Lisa's location in order to improve the
conditions in which it is presented. In October 2004, before the painting was exhibited in its new display
case, the opportunity was taken to carry out a series of analytical tests that brought together a range of
different analytical methods and scientific skills.
In close contact with the work, the aim was to apprehend "the illustrious uncomprehended one,"
as André Chastel finally called the Mona Lisa, not in order to discover a new symbolism, but to explore
its material aspects, in the context of a dialectic which inevitably arises between thought and form.
Leonardo may have written that painting is cosa mentale, 9 but that does not alter the fact that the Mona
Lisa is painted on a wooden panel with materials and a technique specifically developed by the artist.
The use of materials and the artist's know-how have a full part to play in the meaning of the painting.
For the most part no attention, or very little, has been paid to this level of meaning until now, despite the
fact that all Leonardo's historians agree that he approached the world as a scientist, seeking to
understand natural phenomena with all the means that were available at his time.
It was Paul Valéry who wrote that "a work of art should always teach us that we had not seen
what we now see.” 10 His words cannot but remind us of Kenneth Clark's statement: "Yet the Mona Lisa
is one of those works which each generation must re-interpret.” 11 Today it certainly seems appropriate to
study all the dimensions of art works by making use of the considerable advances that have been made
in the science of materials, which in association with the classic methods makes a valuable contribution
to the development of art history.
Many things have been said about Leonardo, his scientific mind, and his art as a painter. He
himself wrote: "For everything one sees, one must consider three things: the position of the eye, that of
the object seen, and that of the light that illuminates it 12 ." As we "look afresh" at the Mona Lisa, let us
follow its creator's advice, which is a true scientific intuition since it expresses not only what he sought
to show with the materials on the painting, but also what scientists were later to discover in their quest
to understand the phenomena of vision and of color, which is a sensation perceived by the eye of light
diffused by an object. Through the rediscovery of Leonardo's delicate, scholarly technique, the work
loses none of its capacity to convey emotion, which led Vasari, quoting the poet Petrarch, to describe
the painting as a work "retarded by desire." 13 It is a desire which in no way excludes an obstinate rigor.
Jean-Pierre Mohen, Michel Menu, and Bruno Mottin
1. Kenneth Clark (London: Penguin, 1993), 172.
2. Giorgio Vasari, Lives of the Most Eminent Painters, Sculptors, and Architects, trans. Gaston du C. de Vere (London:
Everyman, David Campbell, 1996), Vol. 1, 635─36.
3. Kenneth Clark (1993), 172.
4. Cécile Scaillérez, Léonard de Vinci: La Joconde, Collection "Solo" (Paris, Musée du Louvre, 2003), 24, 4, trans. Liz Nash.
5. Daniel Arasse (2004), 98, trans. Liz Nash.
6. Daniel Arasse (2004), 21, trans. Liz Nash.
7. Translated by Liz Nash from Eloge de l'oeil, a selection of extracts from Leonardo's Treatise, trans. Sylvain Fort (Paris:
L'Arche, 2001), 37.
8. Kenneth Clark (1993), 211─13.
9. Leonardo da Vinci, Treatise on Painting (1835), trans. John Francis Rigaud.

10. Paul Valéry, "Introduction à la méthode de Léonard de Vinci," La Nouvelle Revue 95 (1895): 742─70, (and in vol. 1 of
Oeuvres (Gallimard: Pléiade edition, 1957), 1165), trans. Liz Nash.
11. Kenneth Clark (1993), 174.
12. Leonardo da Vinci, Les Carnets (1942), trans. Liz Nash.
13. Giorgio Vasari (1996).

The Practical Sequence of the Study
The direct study of the Mona Lisa centered on three sessions in October 2004. Although these periods
of examination were limited to times when the museum was closed, they enabled the researchers to
gather a considerable body of data which were processed and analysed during the year that followed.
Each of these sessions took place under special security conditions. The number of people
present was restricted, and with very few exceptions those admitted to the immediate proximity of the
painting were limited to four at a time. Any handling of the painting was carried out by restorers. The
sequence of examinations was supervised by one or more curators or scientists from the staff of the
C2RMF and the Louvre. The reception and surveillance teams provided day-and-night security cover.
Special temperature and humidity checks were implemented, and when photographs were being taken,
the temperature of the surface of the work was measured to avoid any risk of heating.
Tuesday 5 October 2004
- Painting taken down by the museum teams;
- Report on condition by Regina da Costa Pinto Dias Moreira, Daniel Jaunard and Patrick Mandron,
restorers;
- Optical measurements by shadow moiré, repeated in the course of the day, with or without the
crosspieces, by the team from the University of Poitiers ;
- Weighings of the painting by the team from the University of Montpellier ;
- Measurement of the curvature of the painting, using the laboratory's normal method, by Jean-Paul
Rioux, C2RMF;
- Measurement of the curvature using a dial gauge, carried out twice by the team from the University of
Florence;
- Measurement of the forces exerted on the panel by the crosspieces, by the teams from the Universities
of Montpellier and Florence;
- Optical measurement of the panel by correlation of the levels of gray, carried out three times, with and
without the rear crosspieces, by the team from the University of Poitiers ;
- Anatomical examination of the edges of the panel, after light cleaning, by the teams from Montpellier
and Florence and by Élisabeth Ravaud, C2RMF;
- Installation of a crosspiecer equipped with a thermohygrometer and a transducer for a continuous
monitoring of the panel's behavior until 3 March 2005, by the team from the University of Florence.
Monday 11 October 2004
- Painting taken down, report on condition, painting packed in case and transported to laboratory, after
museum closing time;
- Measurements of curvature, using the laboratory's normal method, weighing, at beginning and end of
the day;
- Radiographs : conventional radiography, oblique radiography of edges, radiography of layers,
emissiography by Élisabeth Ravaud;
- Examination of the split, listing of visible patterns on the back of the painting by Joseph Gril,
University of Montpellier II, and Patrick Perré, University of Nancy.
Tuesday 12 October 2004
- Measurements of curvature by the normal method, weighing;
- Examination with binocular microscopes, by Élisabeth Martin, Jean-Paul Rioux, Regina da Costa
Pinto Dias Moreira and Élisabeth Ravaud;
- Infrared reflectography by Elsa Lambert;
- Analysis by X-ray fluorescence by Éric Laval and Philippe Walter, on the points chosen after binocular
examination;
- Digital photography, under various lighting, front, back and edges, by Elsa Lambert.

Wednesday 13 October 2004
- Analyses by Raman spectrometry, on points chosen according to previous observations, by Sandrine
Pagès-Camagna and Michel Menu;
- Measurements of curvature and weighing, then return of painting to exhibition hall before museum
opening time.
Monday 18 October 2004
- Painting taken down, report on condition, painting packed in case and transported to laboratory, after
museum closing time;
- Measurements of curvature and weighing;
- Three-dimensional digitization of the front, then the back and edges by the team from the National
Research Council Canada.
Tuesday 19 October 2004
- Spectrocolorimetric analysis by Guillaume Dupuis;
- Attempt to measure the thickness of the varnish by microprofilometry by Jean-Jacques Ezrati, C2RMF
(with no conclusive result);
- Multispectral digitization of the painting using the Crisatel camera, then digitization of the face ;
- Measurement of the thickness of the panel using a mechanical gauge, by Daniel Jaunard;
- Study of the frame and its crosspieces, by Daniel Jaunard;
- Study of the inventory mark, by Michel Dubus, C2RMF
Wednesday 20 October 2004
- Measurements of curvature and weighing;
- Return of painting to exhibition hall, before museum opening time.
Sunday 3 March 2005
- Taking down of painting, report on condition by three restorers;
- Measurements of curvature and weighing;
- Measurement of forces exerted on the panel by the crosspieces, repeating the operations of 5 October;
- Replacement of the existing crosspieces by new crosspieces and instruments which will monitor the
movements of the panel and the forces acting on its upper corners, by the teams from Montpellier and
Florence.
Bruno Mottin