saw, the holes were filled with poplar plugs inserted parallel to the wood
grain. The cross braces were constructed in the same way as those of the
Maestà(Carità 1956).
Another example of even weight distribution is found on
Raphael’s large altarpiece, The Transfiguration,in the Vatican Museums.
The panel is constructed with planks that have been glued together verti-
cally. The Vatican restoration team devised a system similar to that used
on the Duccio altarpiece by hanging the painting on horizontal steel cross-
bars. These steel crossbars are fitted into slots cut into the vertical sections
ofa large metal frame. Clamp screws attached to the vertical frame sec-
tions sustain each of the crossbars. They are calibrated and tightened indi-
vidually in order to distribute the weight evenly over the whole height of
the panel. This gives the heavy panel greatly improved support; fortu-
nately, it has not been thinned and still has the original crossbars.
As mentioned above, many different systems were invented for
building crossbars or braces out of materials such as steel and brass. Many
of these systems were proposed by the Istituto Centrale per il Restauro
(Carità 1953). Today most of them seem rather cumbersome and incom-
patible with the artworks (Carità 1956). The Maestàmetal support system
still seems to be the most functional. One proposal, however, seems
promising: it uses plastic pegs and thin steel rods to hold a panel sus-
pended inside a metal frame (Carità 1956:124–31).
Del Zotto and Tonini (1993) developed some interesting proposals
for extremely flexible battens. Their system makes use of ball-knuckle
joints attached to the panel with hardwood plugs and inserted into a
flexible sleeve that acts as the crossbar. The spring action of the sleeve
combined with the free movement of the joint gives the panel maximum
freedom to move laterally and permits limited movement perpendicular
to the crossbar.
The great flood of 4 No vember 1966 caused enormous damage to
artwork in Florence and Venice. The tragedy helped promote an increased
understanding of the behavior of wood and the effectiveness of some of
the past interventions on panels. Wooden crossbars with pegs made out
ofmansonia^2 proved to be very effecti ve in holding together the water-
logged panels that expanded with absorption and then, upon drying, con-
tracted drastically. Of all the woods that were tried, none has been as stable
as mansonia, which shows practically no deformation or splitting, even
under severe conditions, yet has the necessary flexibility and give. PVA
emulsion glues proved to be very suitable for poplar panels because of the
elasticity of the adhesive, which kept new splits from forming next to the
old ones. The glue had sufficient strength to keep these panels well bonded,
ev en after having been immersed in the flood watersfor up to eighteen
hours. PVA emulsions have been found to be less effective on hardwoods
such as oak or walnut, so epoxy glues are used instead (see Rothe and
Marussich, “Florentine Structural Stabilization Techniques,” herein).
Wax infusions and applications of balsa wood have never been
popular in Italy. While this is principally an aesthetic decision, it may also
stem from the knowledge that once a panel has been impregnated with
wax, it is practically impossible to remove all traces of it. Attempts to
reglue the splits that might form afterward when this method has not been
effective (as with the Resurr ectionby Girolamo da Santacroce in the Blaffer
Foundation, Houston, Texas) can be frustrating (Figs. 21, 22). AnimalC H P P R I 197