Fig. 8: Thin black line on top of the finishing stucco layer covered with limewash.
From: Baroque stucco techniques of Baldassarre Fontana at Kroměříž Château

Sample STK 20 A (A). Reflected light. Black line on top of the first limewash layer. Sample STK 20 C. Reflected light (B). Strong luminescence of the white paint layer containing zinc white (ZnO). Sample STK 2. UV (left) and reflected (right) lights (C). Different luminescence of the first limewash compared to subsequent ones. Sample STK 3. UV (left) and reflected (right) lights (D).