The Structural Conservation of Panel Paintings

noteven visible in the new radiograph. The approximate positioning of

the fragments outside the lower left and right of the oval was now clear.

Enough new information was now available to consider returning the

painting to a lunette format. The respective museums agreed not only

to turn the Washington picture permanently into this format but also

to remove the addition from the Metropolitan picture and to abut the

two pictures one above the other in a single frame made specifically for

theexhibition.

The removal of the addition on the Metropolitan picture was relatively

straightforward. The panel had been thinned to approximately 1 cm

overall and heavily cradled (Fig. 4), and while many splits and surface dis-

tortions were present (Fig. 5), the panel showed no signs of recent move-

ment. It was, therefore, decided to remove only as much of the cradle as

was necessary to facilitate the removal of the addition. The grain of the

addition was oriented horizontally, while that of the original panel was

vertical. Close examination of the joint revealed an extremely asymmetri-

cal tongue-and-groove joint (Fig. 6a). The upper lip of the groove section

measured less than 1 mm thick, which is an unlikely configuration. It was

speculated that this must have originally been a symmetrical joint, the sec-

tions ofwhich measured 5, 6, and 5 mm, for a total of 16 mm (Fig. 6b),

which is still too thin for an Italian poplar panel of this size. Based on

comparison with other unthinned Sienese panels of this period and date,

it seems more likely that the original thickness was between 2 and 2.5 cm.

Once the panel was cut in two, it may have seemed unnecessarily thick. At

this point, it was probably partially thinned (to 16 mm), and the addition,

with a symmetrical joint, was added. At some later date, after slight warp-

ing, the panel and the addition were further thinned, probably to obtain a

flat surface for the application of the cradle, leaving what for all practical

purposes was a half-lap joint.

Removal of the

Metropolitan Addition

T   N  F  G M 345

Figure 4, below
Reverse of the Metropolitan Nativity. The
joint ofthe cross-grain addition can be seen
just belowthe first crosspiece from the top.

Figure 5

Raking light photograph clearly showing

splits and distortions in the Metropolitan

panel and the smooth surface of the addition.