Restoration of Vaulted Paintings in the City Hall Maastricht

In 2018, SRAL restored the vault paintings in the hall of Maastricht City Hall. The decorations covered three vaulted areas: the barrel vault directly above the main entrance, the cross vault, and the cupola vault. These paintings were created between 1667 and 1671 by the Hague painter Theodoor van der Schuer (1634-1707).

Treatment

The primary task involved removing a thick layer of dirt and yellowed varnish applied during the last conservation campaign in 1952. This varnish had significantly diminished the spatial effect of an endless cloud sky with floating figures, a key characteristic of Baroque vault paintings. Additionally, loose layers of paint and plaster were consolidated, and problematic overpainting was either removed or carefully retouched.

Original techniques and materials

In parallel with these restoration efforts, extensive research was conducted on the original painting techniques and supports. Van der Schuer applied his paint to a layer of lime plaster on brick surfaces and marlstone ribs in the dome. In contrast, the cross and barrel vaults were constructed with a wooden framework featuring purlins and curved ribs, between which layers of lime and loam were applied over a slatted fabric. The paint binder was likely linseed oil, which, due to its thin, transparent application, gave the paintings a spherical, matte finish without varnish.

A light grey, streaky ground layer, known as imprimatura, is visible beneath the paintings, particularly in the architectural trompe l’oeil sections. This soft grey layer provided a continuation of the hall’s Dutch classicist architecture, constructed from Namur stone.