The Structural Conservation of Panel Paintings

organic adhesive was selected because it is more easily reversible.^3 The dis-

advantage of its quick setting time was minimized by repeating the clamp-

ing procedure dry several times until the same results could be achieved

consistently, accurately, and quickly. The perimeter was then drawn and

trimmed on the band saw (Fig. 20).

Two crosspieces of the Florentine type described elsewhere (see

Rothe and Marussich, “Florentine Structural Stabilization Techniques,”

herein) were then fabricated and applied (Fig. 21). The contact faces of the

crosspieces themselves, as well as the small retaining pegs that hold the

crosspieces, are machined to an angle of 22.5°. The two rows of pegs cre-

ate a sort of dovetail track within which the crosspiece can slide, allowing

for any lateral expansion and contraction of the panel. The trapezoidal

shape of the crosspiece also permits convex flexing of the panel, and the

small contact faces ofthe pegs minimize friction against the crosspiece,

making it virtually impossible for it to bind. The pegs were attached to the

panel with Ciba-Geigy Araldite 1253 carvable paste, the gap-filling proper-

ties of which make it possible to set the contact between the peg face and

crosspiece precisely, while the resin adequately compensates for any irregu-

larity between the peg bottom and the panel. If inordinate pressure were

eventually to accumulate in the panel from warpage, the small pegs would

tend to delaminate rather than cause the panel to split.

This type ofsecondary support (later abandoned because of

developments described on the following pages) was applied only to a

panel that had previously been thinned considerably for warp reversal or

for the application of a cradle. It would generally not be used for a panel

T   N  F  G M 351

Figure 18, above
Poplar collar used to build up the missing
areas to the surface level of the original
poplar panel of the Washington panel.

Figure 19, above right
Gluing of the collar to the mahogany backing
for the Washington panel.

Figure 20, below
Band sawbeing used to trim the perimeter of
the Washington panel.

Figure 21, below right
Reverse of the Washington panel after appli-
cation of the crosspieces.