Focus on this artwork and analyze the Restoration history.
Despite its large size, the painting was originally painted on wood panels.  The wood used cannot now be identified, but it seems that, like Raphael's Transfiguration, the panel used a number of vertical boards, where a Venetian painting would be more likely to use horizontal ones.  In the 1770s there was a large campaign of restoration of the paintings in the Orleans Collection, which included transferring this and many others from panel to canvas.  According to the National Gallery's detailed account of the restoration history and current condition of the painting: "There can be little doubt that this drastic and dangerous intervention was totally unnecessary".  Much damage to the painting seems to have resulted, and the connoisseur and art theorist Richard Payne Knight wrote that "those who have only seen it since that fatal operation ... can form but very imperfect notions of what it was before".In the 1820s the artist Benjamin West, the painting's "most vocal admirer", is recorded as restoring and repainting damaged areas on Lazarus' right leg.  It was re-varnished in 1834, 1852, and 1867, and cleaned and re-varnished in 1881, after which a sheet of glass was added to protect it from London's air.  After the painting was evacuated in 1939 to Penrhyn Castle to protect it from the risk of German bombing in World War II, losses of paint from flaking were noticed, and various attempts in the following years to stabilize the situation failed.
In 1958 a major re-structuring of the support was done, aimed at reducing the presence of glue in several layers of canvas underneath the paint.  These layers were contracting, causing the paint to lift and flake. It was thought that there were four canvas layers, of which it was planned to remove three. However, as the work was carried out the "alarming discovery" was made that the layer nearest to the paint was actually not canvas but sheets of paper, badly decayed and partly separated from the ground to the paint.  The plan was changed to add layers of warm wax-resin in which an inert synthetic textile was fixed, before attaching to a composite board and paper honeycomb solid support. This method would be unlikely to be used today, but did stabilize the flaking.  By 2009 it was tending to flex when the painting is moved, so this is now avoided as far as possible.After the new support was added much old varnish was removed, and limited retouching performed.  The extensive work, and condition of the painting, allowed the taking of an unusually large number of paint samples, which have now been re-examined using the more advanced scientific techniques available in the 2000s.  This has allowed a good idea of the many complex mixtures of pigments used.With the equipment available in 2009, full examination with imaging techniques that allow underpainting to be seen was not possible.  It was thought that this might shed more light on any contribution by Michelangelo to the underpainting, as it has for the Viterbo Pietà, Sebastiano's first major collaboration with Michelangelo.  By 2017, imaging had indeed revealed that the present figure of Lazarus, based on Michelangelo's drawing, lay over a different figure, presumably designed by Sebastiano.
Raphael Benjamin West Richard Payne Knight National Gallery Lazarus Orleans Collection from panel to canvas London underpainting Michelangelo wood panels Sebastiano Transfiguration Penrhyn Castle