|Wall Paintings at Mogao Grottoes
Adhesive testing on simulated panels. To test the long term stability of adhesives and their resistance to salts a series of painted earthen disks were prepared with earth, sand and straw and contaminated with 2% NaCl (wet weight); half of the disk was painted with a chalk and talc ground and malachite paint layer. 3% PVAC was sprayed on half of the disk (to cover part of the painted area and part of the unpainted earthen plaster). The disks were then subjected to repeat wet and dry cycling; the resulting flaking was then treated with a range of adhesives in varying percentages and cycled again. Photo: Lori Wong.