http://www.kunsthaus.ch/en/the-collection/conservation/examples-from-the-world-of-art-conservation/auguste-rodin/stage-2/touch-ups/?redirect_url=title%3DPer%D0%A0%E2%80%9C%D0%92%C2%A7age

Kunsthaus Zürich

Touch-ups

It was not possible to conserve any patinas under the thick plaster deposits.  These bleak sections were chemically repatinated with cupric nitrate and sulfur compounds.  The surfaces which were entirely greened at he exposed sections were touched up with acrylic resin and in part also with powdered pigments, the color being applied as a glaze.  This technique allowed for all the sections to be visually connected and gave a homogeneous global look. 

Sections with missing patina (Photo:  G. Pegurri)
Sections with missing patina
(Photo: G. Pegurri)
Chemically repatinated sections in comparison (Photo:  G. Pegurri)
Chemically repatinated sections in comparison
(Photo: G. Pegurri)
Acrylic touch-ups (Photo:  G. Pegurri)
Acrylic touch-ups
(Photo: G. Pegurri)
The cupric nitrate and sulfur compounds are applied directly on the bleak metal by means of a brush (Photo:  G. Pegurri)
The cupric nitrate and sulfur compounds are applied directly on the bleak metal by means of a brush
(Photo: G. Pegurri)
Acrylic color touch-ups of the patinas washed away over time (Photo:  G. Pegurri)
Acrylic color touch-ups of the patinas washed away over time
(Photo: G. Pegurri)