A soft wax mixture for the "vernis mou". The heated plate is lightly covered with beef tallow and wiped off, leaving only a thin layer of fat.
The vernis mou is now dabbed on the plate. The heat divides the wax and distribute it evenly over the plate with a leather roller. Allow the plate to cool completely.
Subsequently, a material with structure (tree leaf, for example) can be pressed into the wax. Remove the material and now you can see an image of the material in the wax. Then etch in nitric acid, iron chloride or copper sulphate (zinc), remove the wax layer and ink and print the plate.