thickness, shows considerable joint damage. Despite these observations,
Figure 6a–c shows a painting by Rubens in King’s College Chapel,
Cambridge, that has planks joined horizontally in portrait format. It is
in very good condition. The oak planks are of original thickness; this has
preserved the original joint surfaces and minimized wood movement so
that the panel has remained flat overall.
In “landscape” format, horizontal planks perform better. Joint
strength is increased by greater surface area, and the panel’s center of
gravity is lower.Handling of larger panels
In combination with greater weight, theratio ofcross-grain dimension to
thicknessis usually large enough to give larger panels a greater tendency to
bend when handled or inadequately supported. In other words, for a con-
stant thickness, panels that are larger across the grain become more prone
to bending and subsequent damage. All panels bend when handled, though
bending is not always perceived. Sound panels may withstand considerable
bending stress.
Restraint considerations are more acute for larger panels, because
of greater total movement, greater potential leverages, and weight effects.
Restraint ofmoisture-dependent movement, such as that imposed by restric-
tive framing or reinforcement structures, can increase stresses. A statically
restrained panel may be under considerable stress. Momentum—also a
greater factor when heavier panels are handled or transported—should be452 Brewer
Figure 5a, b
J. M. W. Turner, Story of Apollo and Daphne,
exhibited 1837. Oil on mahogany panel, 1100
31990 3 10 (bevel) to 20 mm (middle) thick.
Tate Gallery, London. Front (a) and back (b)
of a large panel consisting of a single
mahogany plank.
ab