‘Tobias Healing the Blind Tobit’ by Valerio Castello (1650) from the Ferens Art Gallery, Hull, Oil on canvas Conserved and restored with Art Fund support in 2017

• When the painting arrived at the studio there was a heavy deposit of grey surface dust and dirt on the surface. The thick natural resin varnish layers had discoloured and darkened significantly.  The painting had also been extensively filled and over-painted. The fillings were poorly textured and the over-painting was discoloured and had been applied over original paint layers, as well as extensive paint layer abrasion and losses. The paint layer damage, which is estimated to have affected up to 40% of the painting, was likely to have been caused the painting’s exposure to an environment with elevated and fluctuating relative humidity levels, as well as historic injudicious cleaning methods. The dark paint passages had suffered most loss.
• The conservation treatment involved surface cleaning and removal of the discoloured thick varnish layers and extensive over-paint without damaging the original paint layers.
• The painting was in a structurally sound condition. The reverse of the canvas and original stretcher were cleaned and the expansion keys were secured to the stretcher.
• A synthetic isolating varnish layer was applied to the front of the painting. Following this the extensive paint losses were then filled and textured to imitate the original paint layers. The paint layer abrasion and losses were then retouched. 
• Finally a synthetic varnish layer was applied by spray.