Express News Service HYDERABAD: Through the centuries, the composition of lime plaster, a type of plaster widely used for construction or restoration of archaeological structures, has undergone a change. This is because it is hard to figure out the materials that went into the creation of this mortar, apart from there being a difference in quality of raw materials over time. As a result, archaeologists and conservation architects often find compatibility issues between the original lime plaster used in the construction of a structure and the new lime plaster while carrying out restoration works, leading to formation of cracks in the structure.