I’m Susan Hull, Graduate Intern in Book Conservation at Palace Green Library. I have been working with Katie Brew, Assistant Conservator, investigating the materials we use for long term storage of our collections.
Recently we received items packaged in unidentified materials. This is a cause of concern; the rate of deterioration of an archival object can increase by way of the substances surrounding it, including packaging. Unsuitable packaging can expose paper archives to volatile substances, which migrate to the object and ultimately contribute to its degradation.
To assess the materials suitability for long term storage, we contacted Archaeological Conservator Vicky Garlick who runs Oddy testing in the Dawson building, for the students of the Conservation of Archaeological and Museum Objects MA.
What is the Oddy test?
The Oddy test was first developed by Andrew Oddy of the British Museum in the 1970’s. To set up the test, a sample of the test material is placed within a container beside a beaker of deionised water and copper, silver and lead metal coupons. The container is perfectly sealed and placed in an oven at 60 °C for a defined period – usually 28 days. The constant high temperature and humidity artificially ages the test material, so any gases released by it during the test is equivalent to that of 5 or 6 years ageing under normal conditions.
The metals undergo accelerated corrosion, to a variable extent depending on the contents of the test material. A highly corroded metal – having reacted with volatile gases – indicates that the test material would be unsuitable to use as packaging, whereas only slight signs of corrosion indicates that the material may only be used for short term packaging or exhibition. The ideal situation is a metal coupon that shows no signs of change indicating that the test material is suitable for long term storage.
In preparation, Vicky abraded the metal coupons with a glass bristle brush to ensure the surface was clean of corrosion products. The containers – in this case glass jars with silicon seal – were washed with detergent, rinsed and dried to ensure they were free from contaminants. The beakers were filled with 5ml of deionised water and the metal coupons hooked over the edge – ensuring they were not touching one another. These were placed into the jar alongside a 2cm2 piece of the test material. After being sealed they were placed into the oven. As well as the unidentified packaging, we tested 10 other materials used by conservation including papers, cards, leathers, and textile products. In April the test will be complete we will return to review the results.