United States of America 1900s Massachusetts Collection - Set of 10
These postcards of the sweeping hills, cliffs, and towns of the United Staes of America were created using the Photochrom process, a complex method of imbuing black-and-white photographs with relatively realistic color. Invented in the 1880s by a Swiss printer, the Photochrom process began with coating a tablet of lithographic limestone with a light-sensitive emulsion and exposing it to sunlight under a photo negative for several hours. The emulsion would then harden in proportion to the tones of the negative, resulting in a fixed lithographic image on the tablet. Further litho stones would then be prepared for each tint to be used in the final color postcard — a single image could require well over a dozen different stones. Though a time-consuming and delicate endeavor, the Photochrom process resulted in color images with a rare degree of verisimilitude, especially at a time when true color photography was still in its infancy.