A demonstration of sketching made easy, involving a photograph and some chemicals.
Sketching made easy.
M/S as a girl takes a photograph of a Scots terrier, soaks the photo in potassium ferricyanide, washes and dries it, then gets various pens and inks and traces over the treated outline. It is then soaked and washed again until the photograph disappears completely and you are left with the sketch over the top. M/S as the girl holds up the sketch of the dog.