Conservation Rousseau

The partnership with the Fondation BNP Paribas Suisse

The Fondation BNP Paribas Suisse has been partnering the restoration of art works in Europe, Asia and the United States for over 20 years, in the desire to play an active role in ensuring that museum holdings are preserved and can so be passed on to future generations. It has already sponsored over a dozen projects in Switzerland, benefitting the conservation of major works by Max Ernst, Mattia Preti, Auguste Rodin, Bram van Velde and Paolo Veronese. The Fondation Beyeler is delighted to be able to restore three key pieces in its collection with the support of the Fondation BNP Paribas Suisse. Over a period of three years, our team of conservators and curators will devote themselves to the following works: Henri  Rousseau’s painting Le lion, ayant faim, se jette sur l’antilope (1898/1905), Fernand Léger’s painting Le passage à niveau (1912), and the sculpture discussed here, Max Ernst’s The King Playing with the Queen (1944).

Henri Rousseau

Henri Rousseau (1844–1910) is one of the most singular artists of the late 19th century. The fact that he was self-taught as a painter meant that the academic art world, the critics and the public at first refused to take him seriously. His pictures only began to attract attention in the early 20th century, in particular within avant-garde circles. In 1905 Rousseau made his decisive breakthrough at the prestigious Paris Salon d’Automne with his large jungle painting Le lion, ayant faim, se jette sur l‘antilope (The Hungry Lion Attacking an Antelope), a work that today ranks among the absolute highlights of the Beyeler Collection. The jury’s decision to select the painting for the Salon d’Automne marked a sensational turning-point in the artist’s career: having been ridiculed up to that point as an amateur, Rousseau had now earned the official stamp of approval. Le lion, ayant faim occupies a particularly significant place within the artist’s oeuvre. In all likelihood it was painted in 1898 for the Salon des Indépendants, but was only awarded a place of honor at the Salon d’Automne in 1905. It was the first work by Rousseau to be sold on the art market, and it is perhaps due to this commercial success that Rousseau painted over twenty jungle pictures in the final years of his life. Rousseau was greatly admired by the avant-garde and his painting exerted a shaping influence on the course of 20th-century painting. Artists such as Pablo Picasso, Fernand Léger, Wassily Kandinsky, Joan Miró and Max Ernst were profoundly impressed by his art.  

In contrast to the Impressionists and Postimpressionists, Rousseau does not dissolve the pictorial object into shimmering flecks of light and color, but banishes it to the pictorial plane with uncommon directness by means of clear lines and hard contours. Characteristic features of Rousseau’s paintings, and in particular his exotic jungle pictures, are their subtle harmonies of color and form and their tension between objectivity and enigmatic fantasy. His works are carefully composed and infused with extraordinary power and poetry.


The conservation of the painting took just over a year to complete. The aim was to optimize the work from an aesthetic point of view. Although the condition of the paint surface is very good, its visual appearance had become somewhat impaired by various deposits of dirt and small areas of damage incurred in the past.

An imperative first step towards arriving at an appropriate treatment proposal was to carry out extensive in-depth research. By looking at very early historical reproductions of the jungle painting, for example, we were able to draw conclusions about areas of historical overpainting that are clearly visible with the naked eye. Scientific analyses confirmed that these areas of overpainting share similarities in terms of their age and composition with the original paint surface by Rousseau. It must therefore be assumed that they could have been executed by the artist himself. For this reason they were not removed, despite their obvious difference in color (Fig. 1). 

Further examination was able to clarify important questions regarding Rousseau’s painting technique. The artist first sketched in parts of the composition in pencil, then further outlined the main composition in dark, Prussian blue oil paint, before embarking on the actual process of painting. X-rays show that Rousseau attached great importance to the contrast between the dark vegetation and the light sky in the background, since in the final stage he accentuated the gaps between the foliage and branches showing the light blue sky (Fig. 2). 

Our investigation of the paint surface proved particularly fascinating. Over the years a thin grayish film of dirt and localized whitish deposits had collected on the surface. Their removal was one of the main objectives of the restoration, but tests both with solvents and with conventional water-based cleaning methods showed that these attacked the paint surface, which was unusual. The reason for this was revealed by chemical analyses of the paint: Rousseau did not work in pure oils, but mixed these with other media containing proteins (e.g. tempera), which can remain soluble even after more than a century. This insight into Rousseau’s painting technique represents an entirely new discovery and is one we shall be pursuing further beyond the bounds of this conservation project.
After exhaustive tests, we were able to find an alternative dry cleaning method using synthetic latex sponges (Fig. 3). These were wiped gently over the surface of the picture. The resulting “crumbs” of the sponge thereby bound the superficial dirt (Fig. 4). As a result, the painting showed itself once again in its original fullness of color and depth. We can now see the delicate nuances in which the artist has applied his paint.

A number of inconspicuous areas of damage on the picture were also corrected. The numerous tiny losses of the paint layer – barely visible to the eye but nonetheless so numerous that they detracted from the overall effect – were carefully filled and then retouched with pigmented resin (Fig. 5). We thereby worked with great caution and restraint in order to respect the aged condition of the art work and to preserve its originality. 

Henri Rousseau
"Le lion, ayant faim, se jette sur l’antilope", 1898/1905
Oil on canvas, 200 x 301 cm © ProLitteris, Zürich
Henri Rousseau
Portrait of the artist
Historical overpainting
Fig. 1: Detail of the lower right-hand corner of the canvas showing areas of dark green overpainting, probably carried out by the artist himself
Rousseau’s painting technique

Fig. 2: The X-ray on the right shows that, to accentuate the glimpses of sky in the background, Rousseau added extra touches of light blue paint between the foliage at the very end (seen as white on the X-ray)

Dry cleaning method
Fig. 3: Synthetic sponge used to clean the surface
Crumbs of synthetic latex sponges
Fig. 4: Resulting sponge crumbs before and after cleaning
Correction of damage
Fig. 5: Detail of the lion’s nose in the course of restoration: in filled state (left) and after final retouching (right)