The name derives from the subtle extract of antacid soft ground that is extended onto the heated up metal plate. The soft ground is similar to the protective varnish used in other techniques, however, it is softer, as it contains a minimal percentage of either tallow oil or lavender oil.
After carefully placing a sheet of tissue paper on top of the prepared plate, a drawing can be made directly on top of the plate, with a pencil or pastel. The intensity of the chiaroscuro will depend on the applied pressure. The tip of the material used to create the drawing will transfer the soft ground from the metal onto the paper.
Once the design is finished, the paper is softly lifted and the metal is submerged in the acid, which will corrode only the parts where the soft ground has been removed. The effect created resembles that of a pencil or pastel, or whichever material was used.