After the removal of varnish and overpaint, the painting was given a very thin layer of varnish (MS2A resin). This acts to protect and saturate the colours but is thin enough not to mask the very particular surface textures of the egg tempera paint. Areas of loss were filled with a chalk/gelatine filler which was levelled and textured to match the surrounding paint.
From the start, we decided to retouch the painting ‘invisibly’. Missing elements of the composition, for example feet and legs, were reconstructed using the evidence of similar surviving features in other figures. The outlines were incised into the white filler and drawn in with a fine pencil.
The first two stages of the retouching process. The image on the left shows a detail from the painting after cleaning, with damaged areas exposed. On the right the outlines of missing details have been incised into the white background and drawn in with pencil.
Dry pigments were mixed with egg and matched as closely as possible to the surrounding original paint. Final layers of pigment were mixed with varnish to achieve the correct degree of surface gloss. Areas of abrasion or small scale loss were also retouched with pigments bound in varnish. Where overpaint could not be removed from the original paint surface this was painted over to match the surrounding paint.
All the materials we use for retouching are fully reversible and will be removed easily when the painting is cleaned in the future. The egg tempera retouching is only applied over our water-soluble filler so although it produces a very durable paint film it can be removed just by dissolving the filling beneath it.
The last two stages of the retouching process. In the image on the left the missing details have been repainted and on the right the final layer of pigment mixed with varnish has been applied.