LONDON.- Leonardo da Vinci’s Virgin of the Rocks is to go back on display in the National Gallery (afternoon of 14th July) after an 18-month restoration project which started in November 2008. The decision to restore the painting came after several years of intensive study of Leonardo’s work and that of his Milanese associates and assistants – the so-called leonardeschi – from within the Gallery’s collection. The experience gained from examining these pictures reinforced the view that ‘The Virgin of the Rocks’ could not be appreciated as originally intended. The cleaning process began because some varnish that was applied in 1948–9 was particularly unstable and prone to yellowing. Fine cracking in that varnish, and atmospheric dirt which had become absorbed in its waxy surface, meant that the ability of the varnish to fully saturate the picture had become seriously compromised. As a result t