Fig. 6

EDX plots of the two plaster materials. a Typical composition of Material 1 (M1), b typical composition of Material 2 (M2), c plaster containing large amounts of chlorine (Cl) (M2), d plaster sample containing elements such as barium (Ba) and iron (Fe) (M2). Gold (Au) peaks are unmarked, being associated with the standard approach of applying a gold coating to minimise charging