of rust. To ensure this, nail points were clinched deep into the wood. Nail
heads, possibly embedded deeper than the wood surface, were separated
from the ground layer by means of plaster, cloth, parchment, or—in the
most careful constructions—wooden plugs.^30
Here, however, as elsewhere, no definite rules apply. For instance,
in Giotto’sMaestà,although the whole support was conceived and made
with the greatest care (Fioravanti and Uzielli 1992), several nail heads pro-
trude on the front face, bulging through the cloth and ground layer, mak-
ing clearly visible marks on the painted surface.
On some panels, lines for correctly aligning the nail holes may still
be found, especially those that remained protected under a crossbeam and
became visible only upon its removal.Obviously, such lines may be found
only on the back side, since the ground layer deleted or made invisible
those that might have been traced on the front.124 Uzielli
Dowels
Nailsinsertedfromthe front
Nailsinsertedfromthe back0.5m.Figure 19
Drawing showing the placement of nails in
Giotto’s Crocifisso di Santa Maria Novella.