Fifteen glazed architectural bricks were recently rediscovered in the stores of the Middle East and Egyptian Departments. There are very few examples of glazed bricks from 911-612 BC during the Neo-Assyrian Empire (Tallis, pers. comm. 2016).
1. Dry Cleaning Tests
Molecular traps including: Smoke Sponge and Groomstick were used to attempt to remove the ingrained dirt with little success. The pressure needed to remove dirt from the surface could potentially damage the flaking glaze surface. Dry brushing with a soft, sable brush, removed surface dirt, but did little to reduce staining.
2. Wet Cleaning Tests
IMS caused a white bloom on the surface of the object, which can be seen in the image on the right. No further wet cleaning tests were attempted to avoid this bloom.
3. Laser Cleaning Tests
One of my supervisors, Dr. Duygu Camurcuoglu suggested that we test clean the bricks using a Lynton Phoenix Athena Nd:YAG (neodymium-doped yttrium aluminium garnet) solid-state laser with the help of stone conservator, Michelle Hercules. The laser was tested on two areas on brick 92183 and on the Paraloid B-72 label on N2027 at 1064 and 532 nm wavelengths (Figures 29 and 30). At 532 nm, the laser successfully removed ingrained dirt from 92183 but neither wavelength managed to reduce the label on the surface of N2027; it is still visible in the image on the left.