Has anybody tired this ? The direct positive process involved exposing silver chloride paper to light, which turned the paper completely black. It was then soaked in potassium iodide before being exposed in a camera. After the exposure, it was washed in a bath of (Sodium thiosulfate) hyposulfite of soda and dried. The resulting image was a unique photograph that could not be reproduced. Due to the paper's poor light sensitivity, an exposure of approximately twelve minutes was required. Using this method of photography, still subject matter, such as buildings, were favored. When used for photographing people, sitters were told to close their eyes so as to eliminate the eerie, "dead" quality produced due to blinking and moving one's eyes during such a long exposure.