Quote Originally Posted by Prof_Pixel View Post
The Autographic film roll consisted of a tissue-like carbon paper sandwiched between the film and the paper backing. See for example http://en.wikipedia.org/wiki/Autographic_film
This is why when you see a print like this, the writing is white. You could undoubtedly do this on your own, respooling a carbon paper between backing and negative--- I would do a couple experiments to make sure whatever is used to write on the neg will last through the fixer.

I have written on negs after the fact (development) with a sharpie, and achieved a similar effect.