Fig. 9From: Charcoal or black stone? Reconstructions as a tool to study the behaviour of dry underdrawing materials within the paint structure of sixteenth century panel paintings©HPM, HERCULES Lab—U. Évora, PortugalReconstructions of charcoal underdrawing: (top) over linseed oil applied directly over the gesso ground, (bottom) over linseed oil applied over a gesso ground which was first sealed with an animal glue layer. The oil layers had been dried for 30 days before underdrawings were applied. The right half of each panel was brushed with a feather to determine the removability of the lines. All images Back to article page