of wood were applied, and a second orange putty was pushed in from
behind around the new inserts next to the older white putty. These
were now strengthened with dilute PVA (Vinamul 3252) in dispersion.
Realignment of distorted parts was accomplished by softening and reopen-
ing some of the old joins and insets, gradually reweighting, drying, and
gluing them into new positions while the picture was placed facedown.
Voids and worm channels were filled with thin layers of Fine
Surface Polyfilla—a vinyl ester of Versatic 10 (Shell Resin)—PVA copoly-
mer (Veo Va-PVA) with filler and thickener (Caley 1993). The mahogany
insets and oak strips around the edges were left in place as a protection,
but those along the top and bottom edges ran against the grain. Those
insets were sawed through at 1.25 cm intervals to prevent any restriction.
With all of the cracks glued and secured, the panel now took on a convex
warp when seen from the front.
Because the panel was exceptionally fragile, it was decided that a
balsa-wood buildup was necessary to provide support and stability. The
panel was treated with controlled moisture to reduce the warp that had
occurred after the removal of the additions and consolidation of the
cracks and joins. In a departure from the traditional method of suspend-
ing the panel over damp pads, treatment was carried out on the multi-
purpose, low-pressure conservation table, hitherto used primarily for
canvas treatments. The painting was placed faceup on the table and cov-
ered with Melinex (known in the United States by the trade name Mylar)
(Fig. 11). A very mild surface vacuum was applied, and the table was
warmed slightly to 30 °C. Room RH was raised from 55% to 75–80%.
The air circulated in the area under and around the panel; humidification
continued for about an hour.
The panel relaxed naturally, and as it did so, the surface vacuum
was increased accordingly. When the panel had relaxed completely,
humidification was turned off, the surface vacuum was maintained, and
the excess humidity was drawn away from below with the built-in
dehumidifier, bringing RH back to 55% while slowly reducing the temper-
ature ofthe table to 21 °C. The dehumidifier was kept running at the
same setting for several hours. The vacuum was then turned offand the
panel left on the table until the next day, where it had flattened consider-
ably, although it still had a slight frontal convex warp.S C P P N G, L 413Figure 11
Cosmè Tura, The Virgin.Moisture introduc-
tion on the multipurpose low-pressure conser-
vation table.