tures of wax with resins, epoxy resins, and polyester resins) (Straub 1963).
An immersion method is also described. Melting a wax-resin mixture in a
flattub on the hot table is recommended (Straub 1963:138–40). In 1957
Peter J. Hermesdorf modified such a type of wax bath on the hot table for
impregnation (Hermesdorf 1963). Synthetic resins, especially acrylic resins,
have been in use since the 1970s (Unger 1988). Many experiments and con-
servation techniques used for other types of wooden works of art have
not been executed on wooden panel painting supports (e.g., application of
the conservation material under vacuum, or polymerization of monomers
in the degraded object itself ). Current methods are, for the most part,
restricted to local treatments.Flattening of warped panels without cradling or other
auxiliary constructionsFlattening methods used in the past could—at best—be considered restora-
tion efforts rather than conservation treatments. Many such treatment
types ofthe past are also classified today as impractical and inconvenient
for our standards of practice.
Flattening panels with a plane was also preparatory in nature,
inasmuch as flattening was a necessary antecedent to the thinning or
removal of the wooden substance of the support. It was almost impossible
to mount thinned panels on an auxiliary support without prior flattening.
Thus, the flattening of panels was considered a preliminary step to mount-
ing thinned panels on an auxiliary support.Flattening of panels with water
The easiest way to straighten a split or one-sided warped panel is to bring
the reverse into contact with water to swell the wood. When this side is
swollen, the panel is flat. After drying, the panel returns to its original ori-
entation, perhaps becoming even a little more warped than it was before.
Considerable measures must be taken to keep the swollen panels straight.
Lucanus recommended moistening the reverse of the panel once
or twice (Lucanus 1832:114). Welsch recommended moistening every half
hour with warm water until the painting is straight (Welsch 1834). Hertel
recommended spreading moistened fabric sheets over the reverse of the
panel painting (Hertel 1853). Following advice given in a 1912 report at the
Alte Pinakothek in Munich, moistened sawdust was spread over the
reverse of panels to straighten them (Kinkelin 1912:fol. 4; Wolters 1952:8).
In 1952 most of the public conservation laboratories in West Germany
rejected flattening methods for panels that involved direct contact of water
with the wooden surface (Wolters 1952:8).
Wet cloths, wet sawdust, wet sand, and wet split bricks were also
used to allow the water vapor to affect panels in climate chambers or similar
constructions (Wehlte 1958:106). Climate chambers or tents for flattening
panel paintings were more frequently used after 1950 (Wolters 1952:8).
Before the use of climate chambers became more frequent, simple
moistening methods were practiced to prevent the direct contact of water
with the panel’s surface: the warped panels were exposed only to water
vapor. Hampel described how small warped panels can be positioned on a
pot filled with water, remaining there for about twenty-four hours until flat
(Hampel 1846:8). Traditionally, the water was heated. Another humidifica-
tion method, possibly a very old one, involves placing the warped paintingH P P C A, G, S 213