The Library's three tapestries, Radio Telescope, Ram's Head and Parrot are on permanent display in the foyer. They were designed for the Library by the French artist Mathieu Matégot and woven from Australian wool in Aubusson, France in 1968. Being made of a natural fibre they are prone to insect attack.
In July 1990 the tapestries were removed for examination, cleaning, repair and revision of their hanging system. During this treatment live carpet beetle larvae, insect eggs, insect remains, webs and extensive fibre damage was found. After considering various insect control methods, Preservation Services staff elected to disinfest the tapestries by freezing followed by vacuum cleaning.
Reduction of temperature slows down the life processes of living organisms. If the temperature can be lowered quickly, over a few hours, adult insects, eggs and larvae can be killed before their metabolism can adapt to the changes.
Preparation for freezing involved rolling the tapestries on to supporting tubes and sealing them in polyethylene plastic bags which were then evacuated to prevent any condensation problems. In order to monitor the temperature and relative humidity throughout the process, an environmental data logger was placed inside one of the sealed bags. The tapestries were then transported to a blast freezer facility. The blast freezer lowered the temperature of the sealed tapestries to -20°C and they were held at this level for seven days to ensure the process was effective. After this time the tapestries were removed from the freezer and allowed to regain room temperature to prevent fibre damage during transport back to the Library.
After returning to the Library the sealed bags were opened to allow the tapestries to equilibrate with ambient conditions. They were then unrolled and both sides carefully examined and vacuumed prior to re-hanging.
To control a recurrence of insect infestation and its resulting damage this maintenance program is now carried out on an annual basis over a two week period during September or October, the time insects are most active. The process has proven successful with no insect damage recorded since its introduction.
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