Caring for the twentieth-century painting collection at the Scottish National Gallery of Modern Art can often present the conservator with challenges that are quite different from those posed by Old Masters works. For example, a varnish layer may not even be present in a modern work.

Leon Kossoff’s Portrait of Father illustrates the striking improvement possible in the appearance of a painting following a treatment whereby instead of a traditional yellowed varnish, an ingrained layer of dirt is removed from the paint surface.