relation to the first piece.^12 The panel maker was obviously aware that
the joining of boards with the grain running perpendicular to each other
would cause instability—something the conservation history of the panels
confirms onl y too well.^13
The south German Benedictine monk Theophilus (ca. 1100)
describes the process of making panels for altars and wings (Theophilus
1979).^14 The individual pieces for altar and door panels are first carefully
matched with the shaping tool that is also used by cask and barrel makers.
The pieces are then affixed with casein. Once the joined panels are dry,
Theophilus writes, they adhere together so well that they cannot be sepa-
rated by dampness or heat. Afterward the panels should be smoothed with
a planing tool such as a drawknife.^15 Panels, doors, and shields should be
shaved until they are completely smooth. Then they should be covered
with the hide of a horse, an ass, or a cow (Fig. 10).^16 On some altar frontals
in Norway, several of the cracks in the wood of the panel were filled with
parchment prior to application of the ground (Wichstrøm 1982).^17
If the panel maker lacked hide, panels might be covered with a
new medium-weight cloth, with glue made from hide and staghorns
(Cennini 1971:chap. 19).^18156 Wadum
Figure 9
Peter Paul Rubens, Portrait of Helena Fourment,
ca. 1635. Oil on panel, 98 3 76 cm.
Conservation Department, Royal Picture
Gallery Mauritshuis, The Hague. A join
between two planks assembled with a
Z-shaped chamfered overlap (see Fig. 7h)
for better interlocking of the join between
planks with transverse grain.
Figure 10
Lucas Cranach the Younger,Portrait of a
Manwith a Red Beard,1548. Reverse. Oil on
panel, 64 3 48 cm. Royal Picture Gallery
Mauritshuis, The Hague. Two joins reinforced
with horse or cow hair.