The work after restoration

Nostre Dame de Grasse, before restoration. Photo : Prat.	Nostre Dame de Grasse, after restoration. Photo : Daniel Martin

There were several reasons for the final decision to expose the original polychrome, which involved eliminating all the repaints:

• The original polychrome was in an exceptional state of preservation.
• The repaints were flaking off, naturally revealing the original polychrome, particularly on the Virgin’s neck.
• In practice, it would therefore be possible to expose the original polychrome, and there was definitely a considerable advantage to this type of intervention from an aesthetic point of view.

In fact it would enable the medieval chromatic palette to be revealed, as well as the sharpness of the sculpted reliefs which had been coarsened by the repaints. Lastly, the surface of the work would recover a visual unity that would have been impeded had the repaints been preserved.

Exposing the Polychrome

During the intervention, the various repaints were recorded: photographs were taken of each layer of polychrome after a limited surface had been exposed. In addition, small islets of paint containing all the superimposed layers from the repaints were left in areas not generally visible.

The cleaning was carried out mechanically using a fine scalpel, under a binocular magnifier, which explains the length of time taken for the intervention. Only the first repaint on the grey cuff of the Virgin’s robe was able to be removed chemically. Weakened paint layers were refixed throughout the exposure process using vinyl or acrylic fixatives, depending on the degree of matt or gloss required.

Cleaning and Treatment of the Stone

Some of the stone’s deterioration was due to the presence of soluble salts on the surface (sulphates, chlorides and nitrates), but the latter two were also responsible for deterioration deeper in. Only the superficial black layers, full of sulphates, were removed, usually with a scalpel when the dirt covered original paint. On the other hand, this technique was not used on bare stone, and neither were those requiring compresses or aqueous gels, because of the high concentration of soluble salts. As the fragility of the stone prevented any cleaning process using microabrasion, the photoablation technique (laser) was chosen. This is currently the only method capable of perfectly preserving such weakened material.

As the stone could not be strengthened because of the high levels of soluble salts, the sculpture will in future be kept in an environment with a very stable level of humidity, which will be constantly monitored.

Retouches

The original polychrome showed different degrees of wear (lacunae) in different areas. Visual unity was obtained by using watercolours to retouch the parts with the most deterioration (bare stone): these retouches were as minimalist as possible and are completely reversible.