69T
to treating panel paintings infested
with insect species has been to employ a range oftoxic gases
or chemical treatments to control or eradicate the infestation.
However, over the last decade there has been a growing awareness of the
environmental and health implications of using toxic gases or chemical
treatments for pest eradication (Zycherman and Schrock 1988; Child and
Pinniger 1987). Increased legislation in a number of European countries
and in the United States has resulted in the restriction or outright banning
of many toxic treatments. In addition, research has shown that toxic treat-
ments can cause chemical change and damage to artifacts (Dawson 1988).
Insect damage to panel paintings is caused by several wood-boring
species that lay their eggs on unpainted areas of the wood panel. During
the life cycle of the insect, the larvae bore into the wood, forming tunnels
or channels; the adults ultimately emerge through the characteristic round
flight holes. This excavation of the wood ultimately undermines the struc-
tural stability of the panel, which, in turn, can undermine the surface
paint layers. The wood-boring insects that commonly attack wood panels
include the common furniture beetle or woodworm (Anobium punctatum),
death watch beetle (Xestobium rufovillosum), powderpost beetle (Lyctus
spp.), house longhorn beetle (Hylotrupes bajulus), and termite (Cryptermes
spp.) (Schrock 1988). While a wide range of woods has been employed for
the supports for panel paintings, the woods most commonly used in
European panel paintings of the fourteenth to sixteenth centuries are
poplar, oak, and walnut, which are all susceptible to insect attack.
To counteract insect infestation and the structural instability it
causes, panel paintings have been treated with a wide range of toxic gases
such as Vikane, ethylene oxide, and methyl bromide. Many chemical treat-
ments have also been used and recommended in the past (Schiessl 1984;
Serck-Dewaide 1978; Museum1955). The liquid chemicals, applied by brush
or injection, aim to kill any present infestation and have been recommended
because they leave a residue that can prevent reinfestation. These chemicals
include chloronaphthalene, mercuric chloride, Xylamon CombiClear, and
arsenic salts. All of these chemicals are highly toxic, and in many cases,
treatments with them will alter or affect the appearance of a painted sur-
face. The residual effects of these chemicals may have health implications.
There is even some doubt as to the effectiveness of some of these treat-
ments (Hayward 1992).Modified Atmosphere Treatments of
Insect Infestations
Gordon Hanlon and Vinod Daniel