Records suggest that the last time the Hogarth portraits underwent varnish removal was around 1906, when the paintings were sold to the London branch of the Knoedler Gallery. These market-driven restorations typically involved aggressive approaches to cleaning and structural stabilization that damaged paint surfaces.
Today conservators have more sophisticated options to consider when treating paintings, particularly when removing aged varnish coatings. Worcester's conservators methodically designed a specialized formulation capable of removing the varnish layers without risking further damage to the surface. This formulation included a blend of relatively mild solvents and a gelling agent. By thickening the solvent mixture, conservators could better control the rate of cleaning, reduce the varnish layers gradually, and better protect the underlying paint. Here you see William James during cleaning; the lower half after removing the varnish, the upper half with discolored varnish still in place.Next: Re-varnishing