This book covers photographic processes that are usually classified under pigment processes or dichromate colloid processes, although some pigment processes do not use a dichromate salt as a light-sensitive agent. Early French patent literature is consulted and several important mistakes commonly found in the extant English and German literature are corrected. Of interest to conservators and curators are the dates of introduction, degree of popularity, and processing formulas of many printing processes, e.g., carbon transfer, carbro, gum dichromate, Fresson, etc. A chapter titled, On the permanence of carbon prints discusses the permanence of materials (pigments, gelatin, etc.) and processing factors (e.g., image hardening, washing) affecting the lasting properties of pigment images. It is claimed that full color pigment images can last hundreds of years virtually unchanged even when displayed regularly under a safe level of light. -- AATA