In the Darkroom with W. Eugene Smith

Gene always liked to get separations around people, figures, and that was always done with potassium ferrocyanide. It was the contrast that made the prints difficult. Gene saw the contrast with his eyes, but the negative wouldn’t capture it the same way. So he would have to bring the lamp down and burn, and then if that spilled too much exposure and made it too dark, you would lighten it with the ferrocyanide.