 These guidelines were then polished away, and in the cases where they were not removed completely were covered by plaster which has since fallen away.Plaster would also have been used to cover up any mistakes that the sculptor had made, such as with the example of heavy plaster seen on one of the reserve heads in Cairo (60003) where the eye has been recarved.The damage seen to the ears of many of the reserve heads is thought to be due mainly to rough handling by tomb robbers.