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CONSERVATION CASE STUDY

Conserving the Pietà attributed to David

Detail from David's Pieta ©
Pietà©

The Pietà, attributed to Gerard David (c.1455-1523) and workshop, has a thin oak panel support with the wood grain running in a vertical direction. The fine-scale craquelure of the paint film mostly follows the direction of the grain. When the painting was examined, it was found that the craquelure was not stable and that the paint was pushing up with sharp and lifting edges and there was some paint loss. This may have been caused by the oak panel suffering from constriction and compression in a frame, at an earlier time.

In order to prevent further paint loss it was necessary to ‘consolidate’ the area, by delivering adhesive between and beneath the cracks. However, the varnish was so thick that this was not possible. The only way to secure the unstable paint film effectively was to remove the old varnish layers and overpaints first.

Removing the discoloured varnish and old overpaints

Detail of the painting during varnish removal©

Combinations of solvents were used to solubilise and remove the discoloured layers of varnish, using small swabs of cotton wool. This image shows the partly removed varnish over the sky area. It illustrates how the relatively bright blues were obscured by the discoloured varnish.

Once varnish removal was completed, there were still a number of much older retouchings from previous campaigns of restoration, notably along the lower edge, covering old damages.

These may have been caused by flood damage at some point in the history of the painting. It was necessary to remove these older, less soluble retouchings as well, in order to secure the unstable paint film. Solvent gels were used to safely remove the areas of overpaint and old putties without risking damage to the original paint film.

Consolidation and retouching

As the varnish and retouchings were removed, so it became possible to feed the adhesive successfully into the paint film and stabilise the lifting edges of the cracks. It was necessary to consolidate the whole paint surface.

Before
After

Once cleaning and consolidation were complete, the original surface of the paint film was brushed with an isolating coat of varnish, before the old losses were filled with fresh putty and retouching commenced. 

The puttied losses were retouched using dry pigments bound in egg. Egg tempera allows the conservator to build up thin layers of paint to mimic the artist’s technique. In this case, the artist used relatively strongly coloured lower layers that were tempered by subsequent semi-transparent glaze layers to subtly adjust the tones.

Any areas of old damage on the rest of the painting were retouched using dry pigments bound in resin. Finally the painting was sprayed with a further protective coat of varnish.


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