The Structural Conservation of Panel Paintings

losses, and retouching were done. The back of the support had been

planed down, a procedure that removed a small amount of wood. Three

mobile crossbars were attached to the panel with poplar blocks, positioned

in line with the grain of the panel, and glued in place (Fig. 11). The cross-

bars were circular-section aluminum rods that passed through holes made

in the blocks attached to the support.

Restoration proposal

The following solutions were identified: removal of existing tension in the

support; consolidation of the ground and paint layers; repair of the worm-

holes that had weakened the wood; and development of a sound support

and control system for the panel. All of these operations had to take place

with minimal invasiveness to the support—in accordance with a philosophy

that is increasingly valued in the Florence laboratory. In this particular case,

it is apparent—given the small size of the support—that excessive use of

wooden material and glue could potentially damage the painting over time.

Restoration interventions

With the painted surface protected by Japanese rice paper and rabbit-skin

glue, the consolidation of the paint layer was carried out by the vacuum

technique with the same type of glue in a different concentration.^12 Two

temporary crossbars were constructed to hold the painting in its current

deformed state. A gouge was used to remove the supports that held the

crossbars added during the previous restoration, thus liberating the support.

While the temporary crossbars held the support orthogonal to the grain,

the cracks were repaired by small V-shaped tracks opened with the tradi-

tional chisel method. With this operation, the two faces of the cracks were

aligned and prepared for the wedges, and the painted surface was leveled.

This initial phase was essential in giving the disjointed and deformed front

faces a uniformly flat surface. It also made it possible to rotate slightly the

disconnected edges ofthe cracks, while still preventing the back edges of

the cracks from touching. In this way the panel took on an uninterrupted

surface in correspondence with the cracks. To arrive at this solution, the

painting was inserted into a special cagelike structure in which the correc-

tion of the warp and the alignment of the edges was begun (Fig. 12). This

structure, built especially for this project, makes it possible to enclose the

painting at the bottom, top, front, and back. The author and others were

able to work on the edges of the opened cracks and adjust the levels of

the painted surface by means of screws (the heads of which are protected

by wooden caps) that can slide inside the vertical slats of the cage struc-

ture. With the aid of this system, the temporary crossbars were removed

and the profile of the painting corrected. After this procedure, the wedges

made from old oak were fitted, in correspondence with the orientation

of the grain, and a PVA emulsion was used to hold them into place. This

operation was repeated with the other crack.

The holes caused by the wood-boring insects—the problem that

posed the greatest threat to the structural soundness of the support—were

rebuilt with inserts made from the same type of wood as the support.

Triangular or rectangular inserts—depending on the shape and depth of

the holes—were held in place with PVA emulsion.

To restore solidity, control, and protection to the edges ofthe

painting, a perimeter framework was made with the same curvature as the

T R  P P S: S C H 327

Figure 11
Herri met de Bles, Jesus and Saint Peter on the
Water.Back of the panel upon its arrival in the
laboratory.