This charming portrait of the Honorable Augusta Herbert, by British artist John Hoppner (1758–1810), is long overdue for cleaning.

John Hoppner (English, 1758–1810), The Honorable Augusta Herbert as a Child, circa 1795, oil on canvas, Bequest of Mary M. Emery, 1927.401

The varnish is very discolored, grimy, and almost opaque. But the rough surface in the dark landscape indicates the reason it hasn’t been fully cleaned. The artist used bituminous pigments for all the darker hues. Bitumen is tar-based and unstable. It never fully dries but remains slightly soft. The “alligator” texture seen here, most noticeably on the black shoes, is characteristic of bituminous paint. 

Unfortunately, the solvents used to remove discolored varnish will also dissolve bitumen, unless the utmost care is taken. So, we began by cleaning the non-bituminous blue sky.

John Hoppner (English, 1758–1810), The Honorable Augusta Herbert as a Child, circa 1795, oil on canvas, Bequest of Mary M. Emery, 1927.401

As you can see, the cleaning is making a great improvement; likewise on the white dress.

John Hoppner (English, 1758–1810), The Honorable Augusta Herbert as a Child, circa 1795, oil on canvas, Bequest of Mary M. Emery, 1927.401

The areas containing bitumen were then lightly cleaned with a much weaker solution of solvents, allowing for the varnish to be thinned, rather than completely removed, and the bitumen to be unaffected. 

The conservation treatment is nearing completion. While the dark areas were not as cleaned of varnish as the light passages, the landscape has regained depth and clarity.   Shown here in progress, after cleaning, the color balance and legibility have noticeably improved.

John Hoppner (English, 1758–1810), The Honorable Augusta Herbert as a Child, circa 1795, oil on canvas, Bequest of Mary M. Emery, 1927.401

Look for the Honorable Augusta Herbert to return to Gallery 209 in the next few weeks!