I engrave my topographical line drawings into Aeroply to define the boundaries of my composition. To achieve a full-value dark from a collograph plate, I apply an evenly textured surface to the plate, like an aquatint, that will hold enough ink to print well. The richest black is achieved with Carborundum, or silicon carbide. After the gesso has dried and the excess silicon carbide removed, I seal the plate with several coats of polymer gloss medium or PVA to hold the grit in place. The tonality of the geomorphology can be controlled by adding more coats of PVA to lighten the tone.
I employ colour by inking the highest levels of the plate with relief rollers. Because the plate holds more ink that an etching in its textures it makes the wiping more difficult and time consuming. The tonality of the impression can vary greatly and the amount of ink left on the surface of the plate is critical. Only by taking proofs ca you tell what the print will look like.
