Cliche-verre means literally 'glass picture'. It is also known as glass etching or hyalography (back to the old business of dredging the Greek and Latin dictionaries for fancy names - in this case the Greek word for glass). The method was used regularly to good effect by the French painters Corot and Millet. It is essentially a hand drawn negative and as such is difficult for historians and students of old processes to categorise. Perhaps it illustrates the currently held view that the artist's ideas are more important than the medium through which they are expressed.

Corot and his contemporaries took a piece of flat glass, smoked it over a tallow candle, and then scratched an image in the soot covered surface with a sharp pointed instrument. This was placed onto a sheet of photosensitive paper and exposed in the sun. When the light passed through the clear parts of the glass where it had been scratched, it produced a line drawing in black on a white background. This could be reproduced ad infinitum without resorting to the making of an etching plate and the use of a heavy and bulky printing press, or even more important, without having to pay for the services of a printing studio. If you insist on being completely historically correct you can use the smoked or varnished glass method, but there is a much more flexible improved way of working which give opportunities for many more variations of effects. This involves the use of a sheet of fogged lith film. It may not be quite so authentic but it is close to the spirit of the thing without having to 'invent' a new old process.