Monday, 16 July 2012

The conservation of a kato alu basket

Some of the objects in the Cook-voyage collections of the Pitt Rivers Museum need interventive conservation work, to stabilise them for display or research.  The Tongan baskets which I've talked about in previous posts are examples of this.  The kato alu in particular has been badly crushed in the past, and the palm leaf midribs that make up the framework of the basket have been broken.  The basket has also become distorted, making any repairs even more difficult to achieve.

Discussing the treatment of the Tongan baskets

Before undertaking a treatment, the conservators at the Pitt Rivers often discuss the options. Sometimes, the general feeling might be that an interventive treatment is not necessary, and that with careful packing and handling further damage to an object can be avoided.  Sometimes though, as with the kato alu, something needs to be done to stabilise damaged areas. 

There were two stages to the conservation treatment of this basket.  The first was to attempt to re-shape it, bringing the broken areas back into alignment.  This was done by making an internal support which allowed the basket to rest upside down.  The basket was then humidified, by placing it in a humidity chamber made from polythene and introducing water vapour, produced by an ultrasonic mister. This uses a metal diaphragm vibrating at ultrasonic frequencies to generate very fine water droplets at room temperature.

The kato alu basket, 1886.1.1328 in the humidity chamber

The vapour is absorbed by the plant material, making it more flexible and easier to manipulate.  The basket was left in the humidity chamber for an hour, and was then flexible enough to reshape gently, holding the new position with pieces of foam tied around the basket with cotton tape.

Reshaping the basket

The basket will be humidified several more times, and the foam adjusted until it has reached a shape more similar to the original.  The breaks in the kato alu will be secured on the inside of the basket with strips of Japanese paper, tinted with acrylic paint to tone in with the colour of the basketwork.  In this way, the broken edges will be protected, and the possibility of future damage or losses reduced.