The 600m2 of frescoes in the Forum created by Pierre-Henri Ducos de la Haille in 1931, were restored in 2011. The restorer, Cinzia Pasquali explains what this work entailed. 

The walls of the Forum as well as those of its mezzanine are decorated with frescoes (approximately 600m2) by Pierre-Henri Ducos de la Haille, and his students of Fine Arts. The theme of these frescoes, dating to the 1930s and commissioned for the colonial exposition, is France’s intellectual and moral contribution to its colonies: science, freedom, justice... (learn more about frescoes). Besides these frescoes, a decorative painting known as a "savannah" covers the vertical structures and the upper part of the forum.

If part of the frescoes were restored in the 1980s, those on the mezzanine had not been since their creation. In any case, the frescoes and decorative painting had continued to deteriorate due to the life of the building and restoration had become necessary.

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What does the term “fresco” mean?

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Détail des fresques du Forum. Représentation de l'industrie, photo Cinzia Pasquali, Arcanes © Palais de la Porte Dorée

It is often used abusively in everyday speech to designate any mural painting and more rarely the technique. The word comes from the Italian a fresco, which means “in the fresh”. It is a particular technique of mural painting on plaster, before it dries, called intonaco. Painting on plaster that has yet to dry allows the pigments to penetrate the support, and hence for the colors to last longer than a simple painting. This technique requires a great mastery of drying times and the painting must be done very quickly, between the time the plaster is applied and before it dries completely. 

How were the Forum frescoes painted?

The artist interpreted the classical fresco technique by adjusting it to his esthetic and stylistic preoccupations. He did not use the principle of smoothing the fresh plaster like the Romans or during the Renaissance. He rather sought a rough texture, which confers a light, matte and slightly softer aspect to the painting, very similar to the esthetics of the Nabis movement (Maurice Denis). It was by an increase in the proportion and the granulometry of the sand that he arrived at this result.  

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Détail des fresques du Forum, photo Cinzia Pasquali, Arcanes © Palais de la Porte Dorée

If we go into further detail, it is a technique achieved with only two layers of plaster. The first, for the preparation of the wall, is very coarse and probably done with sand and cement instead of lime. The second layer, which receives the paint (the paint layer), is of variable thickness, between 0.5 and 1 cm. It is composed of lime and sand of average particle size.

If the technique is not classical, the characteristics of its execution are typical of fresco: the paint is very fluid and the contours are emphasized with a brown brushstroke. The palette is composed of earth colors for the greens and the browns, ferrous oxide for the reds and yellows, ultramarine, carbon black and calcium carbonate white. The figures’ names, inscribed above in white cartouches, are written in oil gilding.

In what state of conservation were the frescoes before you worked on them?

The frescoes underwent several types of alteration. First, alterations in the plaster that tended to crumble. The important proportion of sand may have caused this loss of cohesion, resulting in the presence of multiple detachments of both plasters. This type of alteration is therefore probably due more to the execution than to the conditions of conservation.

We also noted alterations in the paint layer, which was also affected by a loss of cohesion that resulted in great mechanical fragility.

And the last type of alteration: alterations of the surface. These alterations were very different in the Forum and in the mezzanine. In the Forum, they were mainly of accidental origin, due to the presence of the public, and as a result especially situated on the lower part (hand prints, soles of shoes, etc.). On the whole of the surface we also observed a thick layer of dust and dirt due to pollution (heating, urban traffic, presence of visitors).

On the mezzanine, the state of alteration was far greater than in Forum especially due to the installation, in the 1950-60s, of furniture and display cases.

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Exemple d'altération sur les fresques du Forum, photo Cinzia Pasquali, Arcanes ©  Palais de la Porte Dorée

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Exemple d'altération sur les fresques du Forum, photo Cinzia Pasquali, Arcanes ©  Palais de la Porte Dorée


In what state did you find the decorative painting?

The decorative painting covered the columns in the Forum and the mezzanine, as well as inside and outside the balustrade, the ceiling, and the lower part of the mezzanine’s walls. It was executed on the same plaster as the frescoes, using a sponge in a brown-orange hue directly on the plaster.

A great part of this decorative painting was redone in the past but in a very coarse manner. The parts that were redone had a shinier surface than the original, the brown-orange was a darker color, and the sponge technique was more mechanical and dense. It is even more noticeable where the original parts of the painting were preserved on the mezzanine. Esthetically speaking, these original areas, even if they have deteriorated, remain much more in tune with the frescoes, both for the colors and the materials than the previously restored parts that have had to be redone.

What did restoration involve? 

What we did was a little different in the Forum and in the mezzanine but generally speaking, our work consisted of three stages: cleaning, consolidation-re-fixing and restoration.

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Restauration des fresques sur une zone test, Cinzia Pasquali, Arcanes, © Palais de la Porte Dorée

First, cleaning: we meticulously examined the frescoes’ surface to identify the alterations, before removing the dust with a soft brush and a museum-standard vacuum cleaner. Then we cleaned by hand with a medium hard wishab-type sponge. Cleaning is a delicate task but it is indispensable to successfully re-fix the paint layer. Moreover it leads to a significant esthetic improvement: the colors are brighter and the painting regained all its depth particularly on the mezzanine.

Next come the consolidation and the re-fixing: we consolidated the plaster by injecting an acrylic resin and then we re-fixed the paint layer with an acrylic resin in solution. The consolidation of the plaster had to be done in a systematic way on the whole surface since its deterioration is due to the execution of the frescoes more than to external alterations. 

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Restauration des fresques sur une zone test, photo Cinzia Pasquali, Arcanes, © Palais de la Porte Dorée

Then the final stage, restoration: we filled the defects with lime mortar and marble powder and retouched the altered parts with watercolors.

It was at this stage that the decorative painting was also treated with a view to giving back coherence to the whole. This painting participates in the decorative effect of the room and because of its expanse, affects the way the frescoes are viewed. As a result, it seemed hard to imagine keeping the decorative painting in its present state, since its colors and materials did not combine well with the fresco areas. It had to be returned to its original aspect.

It was at the end of this stage that the ensemble regained all its clarity.

Interview with Cinzia Pasquali, Atelier Arcanes in May 2011