Traditional etching grounds and retouch grounds can contain the following ingredients: Bitumen from Judea (asphalt), terpentine, wax, dammarresin, petrol, colofonium and tar. It is used to cover the etching plate, making it resistent during etching. After covering the plate with the ground (by roller or brush), the drawing in made in the ground. Covering varnishes are made to cover the non image side of the plate, but some sorts are also used to cover parts of the image side during fased etching.