the desired edge rather than to “cartwheel” the panel from one edge to
another. When leaning a large panel away from a vertical position, it is
also important to stop the bottom edge from sliding out. Weight directed
at an angle to the floor can cause uncontrollable slides.
The greater mass oflarger panels creates greater inertia, so rapid
movements increase the likelihood of bends and twists. Twists or torsions
cause stresses from many angles and are probably the most dangerous pos-
sibility (Gordon 1978:chap. 12). In describing the twisting of plates in rela-
tion to thin wooden panels, Bodig and Jayne have noted that a body in
pure torsion is in a state of pure shear stress that is concentrated at the
upper and lower surfaces (Bodig and Jayne 1982:165). Essentially, when a
plate sustains a twist, one pair of diagonally opposite corners are forced
closer together, while the other two corners are forced further apart.
Boxlike structures or diagonals resist these distortions more efficiently,
andthey have been employed in some original reinforcements (Marette
1961:pls. 22, 23; Castelli and Ciatti 1989:142–43).
Twists can occur even with seemingly robust auxiliary supports,
such as thick battens. The additional weight of the auxiliary support can
increase the danger, as it is usually supported to some degree by the panel
itself. A thicker panel resists bending and torsion better.
It is usually better to carry large panels with the grain held verti-
cally. They should rest on an end-grain edge and lean slightly away from
the painted side. During handling, great care should be taken if panels
are laid horizontally or on a longitudinal-grain edge. The momentum
of movement is transferred more dangerously to a horizontal panel,
while buckling may occur in the latter case. Over longer distances, well-
supported trolleys alleviate stresses on panels and bearers (Fig. 7). It is
important to have the route clear and to have the panel’s destination pre-
pared for both breadth andheight.Temporary auxiliary supports
It may be useful to build a temporary auxiliary support^17 if a large, weak-
ened panel is to be moved frequently or treated extensively. Designs can be
tailored accordingly.454 Brewer
Figure 7
Alarge panel being transported on a
custom-built trolley, attended by qualified
personnel (1987).