New Insights into the Cleaning of Paintings

206 • smithsonian contributions to museum conservation
FIGURE 1. Canvas painting of the St. Martin’s Battle, showing water staining before cleaning operation.
FIGURE 2. Cleaning test examples. On the left. agar gel after the
application of cyclododecane proved effective. On the right. the laser
proved rather ineffective.
FIGURE 3. (left) Agar gel applied to a water- stained area. (middle)
Wet appearance of the surface after the removal of the agar gel.
(right) Inhomogeneous appearance of the area after drying.
On areas unstained by water, better results were obtained
during the first cleaning tests. The cleaning was more homogenous,
the surface dirt removal was effective, and the paint layer
was not damaged (Figure 2).
On the other hand, on water- stained areas, different results
were obtained. This might have occurred because the surface was
weaker, so that even a minimum amount of water was too aggressive
to the paint layer. When the agar gel was removed, it
ripped off the paint layer in an irregular way, and no uniform
results could be obtained (Figure 3).
It is difficult to understand how the contact between two
theoretically incompatible materials, i.e., cyclododecane and
agar, could result in an effective cleaning operation. As the cyclododecane
is a hydrophobic material, it was expected that it
would repel the surface water, thus preventing the action of the