Bichromate Gum advancedBichromate Gum is a photographic printing process invented in the early days of photography. William Henry Fox Talbot found that sensitized dichromated colloids such as gelatin and gum arabic became insoluble in water after exposure to sunlight. Alphonse Poitevin added carbon pigment to the colloids in 1855, creating the first carbon print. In 1858, John Pouncy used colored pigment with gum arabic to create the first color images. We rediscover gently