Curing the salt contamination in a pair of Imari vases. A serial conservation mystery, episode 2
In May we discovered that the Imari vases which had been brought to the lab from Wilton House were suffering from a case of salt contamination http://wshc.eu/blog/item/the-conservation-team-turn-detective.html. The salt had caused large cracks up the side of the vases reducing their structural stability and causing loss of some fragments and areas of glaze.
Developing a treatment
Removing salt from an object is best completed by dissolving the salts into water and removing the contaminated water from the vase taking the salt with it. If not all the contaminated water is removed during the treatment some salt will remain and the process of crystallisation will begin again, causing further deterioration.
To try out our treatment options we needed to create some test patients with similar symptoms to the Imari vases.
Undertaking clinical trials
The test patients were contaminated with salts from the base up to simulate the issue with the Imari vases.
Due to the size, weight and fragile nature of the vases treating only the affected area would be the ideal solution. We tested using a poultice made from blotting paper, cartridge paper and distilled water.
To use a poultice you apply a thin layer to the affected area and allow to dry. As the water evaporates from the surface of the poultice the salty water in the centre of the pot is drawn out and the salts are deposited in the poultice. The dried poultice can then be removed taking the salt with it.
The clinical trial turned out to prove the treatment was not effective, instead of evaporating from the poultice some of the water was drawn into the test pot and evaporated from the exposed rim leaving the salts behind.
It was clear that a plan B would have to be developed....