<div class="chapeau">BEFORE INSTALLING THE PINAULT COLLECTION IN ITS NEW HOME AT THE BOURSE DE COMMERCE IN PARIS, WE BEGAN BY RENOVATING AND ADAPTING THIS IMPORTANT HISTORIC MONUMENT TO ITS NEW
ROLE. THIS EXCEPTIONAL TREASURE OF FRENCH CLASSICAL ARCHITECTURE, WITH ITS UNIQUE CIRCULAR PLAN AND STRUCTURE, WAS DESIGNATED A NATIONAL HISTORIC LANDMARK (AND GRANTED
THE PROTECTIONS INHERENT THEREIN) IN PROGRESSIVE STAGES: FIRST, THE MEDICI COLUMN IN 1862; THE BOURSE DE COMMERCE BUILDING ITSELF IN 1975; AND FINALLY ITS DOME, DESIGNED
BY FRANÇOIS-JOSEPH BÉLANGER, IN 1986.</div>
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<span class="title">LA RESTAURATION DE L’ÉTAT 1889 /</span><br>
<span class="title">RESTORATION OF THE BOURSE DE COMMERCE</span><br>
<span class="title">RETURN TO ITS CONDITION OF 1889</span>
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Chief Architect of French National Heritage
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<span class="alinea"></span>Given the significance of this architectural complex, we adopted an investigative approach, relying on in-depth archival and documentary research and structural in-situ analysis,
using non-invasive tools such as ground-penetrating radars. We were able to reconstruct the complex history of the site and its successive identities,
culminating in its most complete state in 1889.
<span class="alinea"></span>A structural analysis of the edifice revealed previously unknown details concerning its internal structure. We were able to image the subsurface of the building
and obtain a precise picture of its metallic floorboard structure. We found traces of materials that were commonly
used in the nineteenth century, but no longer employed today: tiles of plaster, limestone, and clay used to form dividing walls, slabs of thick glass used in the flooring of the hallways.
<span class="alinea"></span>This extensive study was key to meeting our goal of restoring the building to its condition of 1889. We conceive of restoration as a specific approach to a project,
founded on the analysis of fragments of history that must be carefully studied, archived, and preserved. Our goal was to restore the Bourse de Commerce to its former glory,
even preserving the memory of the ancient Halle au Blé within it.
<b>Cleaning the external facade</b><br>
The external facade was studied in turn; we determined it was made of Saint-Leu limestone. Today, the cleaning of a building’s exterior—a standard practice in restoration—must meet
rigorous environmental norms and standards, so we used specially designed procedures to eliminate deposits of lead dust and return the facade to its original color.
<b>Protecting the mosaics</b><br>
The marble mosaic tiles that line the interior of the vestibule and rotunda had to be installed in concentric circles: the position of each slab was indicated on its reverse side,
marked in alphabetical order from A to Z then AA to AJ, thirty-six rows in all.
<b>Restoring the long-destroyed carpentry</b><br>
In order to return the building to its condition of 1889, we had to carefully reconstruct certain elements of the edifice that had been destroyed. We wanted to use the original construction methods,
which required us to create working drawings and architectural scale models in order to examine means of integrating more high-performing, modern windows.
We assembled archival documents that allowed us to analyze the original carpentry of the facades, relying on abundant photographic evidence, including several snapshots conserved at the Musée Carnavalet.
<b>Reinforcing the structure</b><br>
Henri Blondel, the architect responsible for the building’s adaptation into the Bourse de Commerce in the late nineteenth century, employed innovative construction
methods pioneered at the time for industrial architecture. The floor of the rotunda is supported by an iron framework on cast-iron columns. To avoid the overload stress that the transport
and installation of heavy artworks could entail, we reinforced some columns using cutting-edge metallic alloys, while others were replaced by replicas constructed in the historic
foundry in the Val d’Osne, in Haute-Marne.
<b>Painting the iron framework of the dome</b><br>
When converting the Halle au Blé into the Bourse de Commerce in 1889, Blondel altered Bélanger’s famous dome from 1812. Our analysis showed that the iron pieces,
originally painted black, had been covered in a dark shade of grey by Blondel: we decided to recreate that color.
<b>Replacing the glass canopy</b><br>
Blondel also transformed the exterior of Bélanger’s dome, replacing the original copper sheeting with zinc and slate plates, which we are restoring.
We took into consideration not only esthetic factors, but also emphasized the use of original construction methods.
<br>Restoring the glass canopy was another ambitious goal. We wanted to integrate new types of glass to the external façade, which would allow us to improve the environmental conditions
inside—a necessary requirement for the conservation of the works in the collection. These new types of glass achieve better performance levels (temperature control, use of natural light and solar heat)
than the traditional panes of glass, last replaced in the late 1990s. We’ve now managed to restore the original lighting conditions, also taking into consideration the conservation of the collection.
The wrought-iron roof light at the top of the dome is shown in drawings by Hittorff, in the collection of the Wallraff Richartz Museum. Here, given the delicacy and geometric complexity of Bélanger’s
iron structure, we had to use a simple pane of glass.
<b>Restoring the paintings</b><br>
Henri Blondel decorated the dome of Bourse de Commerce with paintings on canvas affixed to the walls. Above four entablature, Alexis-Joseph Mazerolle,
also responsible for the frescoes lining the ceiling of the Comédie Française, created trompe-l’oeil allegories in grisailles of the four cardinal directions.
Four artists were commissioned to depict the history of commerce across the five continents: Evariste-Vital Luminais (America), Désiré-François Laugée (Russia and the North),
Georges-Victor Clairin (Asia and Africa) and Hippolyte Lucas (Europe). These paintings, in oil on canvas, are coated with an adhesive called ‘céruse’ (a technique called ‘marouflage’)
and affixed to the walls of the dome, across a surface of close to 1,400 square meters (around 140 meters long by 10 meters high).
The restoration revealed that the painters, faced with the challenging geometry of the dome, came up with various tricks to adapt the shape of the canvas to the curvature of the wall.
By studying the shape of the canvas support, we were able to establish that they were installed in two steps: first, the top, depicting the sky; then the landscape below. Each of these two sections
was then further subdivided into sections, nailed to the walls in a precise sequence. The painters cut notches in the canvas so it could adhere perfectly to the curvature of the dome.
The canvases were prepared in a workshop and finished onsite, where additional figures could be painted in or cut out, as the team of workmen rushed to complete the installation
before the building’s official inauguration during the Exposition Universelle of 1889.
By cleaning the canvas and filling in micro-fissures in the varnish of the paintings (apparent as opaque white blotches on the surface of the canvas),
we were able to restore the original colors of these paintings and the distinct personality of each artist. New details, in particular in the industrial landscapes of Europe by Hippolyte Lucas, were revealed.
<b>Conservation of the Halle au Blé</b><br>
During the restoration of the building, we discovered certain vestiges of the Halle au Blé. Graffiti from 1766, incised into the Medici column, are now visible,
as well as elements of the barrel-vault dome that covered the top floor of the Halle to protect the stocks of grain it contained from leaks and fires. Until now,
this celebrated design was known only through a few rare drawings by Le Camus de Mézières.<br><br><br><br><br><br><br><br>