Wood is, of course, an ideal material for movable paintings and
altarpieces. It is strong, relatively light, and self-supporting. It can be
planed smooth or carved in relief, and it is equally appropriate for the
simplest of panels or the most fantastic of carved structures. Its resilience
and autonomous strength can also be considered a long-term disadvantage,
however, since both strengths allowed later predatory collectors to dis-
member great works into smaller, freestanding parts, beginning the
process by which panel paintings have been scattered randomly and out
of context in collections around the world.
Much recent technical research on early Italian altarpieces and
other panel paintings has concentrated on reassembling (on paper, at
least) the original sequences of now-separated fragments, such as those of
Ugolino di Nerio’s Santa Croce altarpiece, which are dispersed among col-
lections in Berlin, London, and Los Angeles. The very nature of wood can
be vital in this quest, as horizontal predelle and vertical registers of the
great altarpieces were often painted on single, massive planks. To anyone
who has bothered to look at the backs of such altarpieces in situ, this is
a simple and obvious fact. However, only in relatively recent years have
X rays been used to clarify the original structure of dismembered altar-
pieces by following wood-grain patterns through rows or columns of
separated sections. X rays make it possible to reconstruct the widely
scattered fragments of Ugolino’s altarpiece into seven separate vertical
units, each based on a massive poplar plank. The wood grain in these
reassembled planks runs continuously from the tops of the pinnacle
panels to the bases of the three-quarter-length saints. The predella, now
separated into seven separate panel paintings, consisted of an enormous
plank more than 4 m long.
X rays and visual examination also rev eal the presence ofirregu-
larly spaced dowel holes down the sides of the seven vertical tiers; the
holes—which only match up if the panels are correctly arranged—were
clearly used to link adjacent planks. Faint batten marks on the backs of
many of the panels indicate an original structural framework that sup-
ported the entire altarpiece. A stepped, or half-lap, shape at the side of
each vertical plank suggests that the makers created the altarpiece so that
it could be executed in separate sections and assembled in situ by pegging
the planks and overlapping battens together. Remaining pieces of metal
fixings on each vertical tier indicate the previous use of an overall metal
strut to support the whole structure.
Deductions such as these, which bring to life the working methods
of late medieval artisans, are vital if we are to understand works of art in
context. These lines of research demand from each conservator of panel
paintings that each join, hole, notch, nail, or mark on the backs and sides
of panels, whatever its period or origin, be scrupulously preserved and
recorded for the sake of future scholarship. As part of this symposium,
conservators discuss the ethics of thinning panels and applying secondary
supports—procedures that have, in the past, concealed or destroyed impor-
tant evidence. Let us be sure in the future that not a single clue to the orig-
inal structures of panel paintings is lost or concealed without adequate
documentation.
Documentary evidence from the great ages of European panel
painting—from medieval times to the Baroque—is somewhat sketchy.
Some documentation is marvelously complete, such as the contract for a
polyptych painted in 1320 by Pietro Lorenzetti for Santa Maria della Pieve
I: K A xv