Veränderungen der Bildoberfläche bei der Dünnung und Abnahme von Firnissen. Ein Beispiel aus der Kasseler Gemäldegalerie Alte Meister

Alteration of the paint surface when thinning and removing varnish. An example from the Kassel Gallery of Old Masters This papers presents an extraordinarily difficult case of restoration for which no completely satisfying solution has so far been found. The painting of the Dutch baroque painter Melchior de Hondecoeter (1636–1695), The White Hen with Chicken, possesses a thick and strongly yellowed varnish, like many paintings of the Kassel Gallery. The varnish shows bark-like deformation in the extensive pentimento. It is there that the paint layer has partial intermediary varnishes, it is therefore extremely sensitive to solvents. Removing or thinning the varnish with the aid of solvents is not feasible. As an alternative, a merely mechanical thinning by abrasion with varnish powder was tried. The result is a flattened varnish surface disturbing on the cloddy painting. This case study also shows the possibilities of light-microscopic examination and documentation.