Guiding-lines on the Vellum: I ruled pencil lines on the vellum according to the prickings and ensured their straightness with ruler and triangle. Next, I dabbed areas to be inked with the gum sandarac bag and brushed off the excess. The ruling pen was filled with walnut ink and the outsides of the pen cleaned off, then the flat side of the pen was drawn smoothly down the edge of the ruler, creating lines of chosen width.