During initial examination, various surface phenomena suggested that the paint layer possibly had a support of paper or parchment and had been adhered to a much later, integrally framed panel. The panel and frame are carved out of a single piece of walnut. This seemed an unusual choice for a Netherlandish painting of the fifteenth century, when oak was the most common support, and rather more typical of the nineteenth century. However, subsequent, repeated, and more detailed and intimate examination made it clear that Gerard David's Christ Blessing is not on paper or parchment nor has it been transferred. On the contrary, the painting is actually executed directly on the integrally framed walnut panel. The undulations in the surface and the vertical indentation through the centre of the face are actually the result of compression stresses in the paint layer brought on by shrinkage of the support. This also seems to have been compounded by the extremely thick gesso used over the frame (see below).
In general the paint is in good condition with only a few tiny losses. It is thinly painted and certain areas have become more transparent over time. In particular, the fine curls of Christ's hair which extend beyond the original reserve left for the head and on to the blue azurite background, are now somewhat abraded and consequently appear less distinct. This change no doubt accounts for the gilded rays that were present prior to the recent cleaning and that had been added during a previous restoration in an attempt to define the contour (see Additional Images). These gilded additions almost certainly belonged to the same campaign of "enhancement" that was responsible for the incongruous "Salvator Mundi' inscription along the neck of the tunic. In both cases, it was clear under magnification that the gilded ornamentation lacked the requisite refinement one would expect of the artist and more conclusively, lay over the craquelure in numerous places.
On acquisition the painting seemed to have been relatively recently restored. It had a thin coating of varnish which, though possessing an even gloss, was not entirely sympathetic to the paint surface. It also proved to be rather more discolored than first anticipated.
The most pressing need in terms of treatment was the removal of the later gold paint on the frame, which was jarring and detracted significantly from the precious painted image. Following examination, it was clear that the gesso was contemporary with the gold paint and was unnecessarily thick. After discussion with curatorial colleagues the decision was made to remove this gold paint and gesso completely. The discolored varnish and retouching were also removed, revealing the high quality of the minute but painterly execution. Careful attention was paid to the very edge of the image where accretions of dirt and varnish covered small but crucial details, such as the tips of the fingers that appear to rest on the very edge of the frame. The gilded rays and inscription were removed under the stereomicroscope.
Regilding of the Frame:
During the removal of the gesso close attention was paid to finding any remaining fragments of what could be an early finish or gilding. In the crevices a few miniscule remnants of gilding were discovered which were used for analysis. Following discussion, it was agreed to re-gesso the surface in a more sympathetic manner and, based on contemporary examples, to opt for a suitably patinated, water-gilded finish, with a black outside edge to match the sides.
Following completion of work on the frame a thin solution of natural resin varnish was applied to the paint surface and the losses retouched.
[Extracted from the Condition and Treatment Report by Michael Gallagher, 2010]