The picture postcards that became widespread at the dawn of the 20th century were the products of recent revolutions in the technology of printing. They may look like photographs, but in fact, almost all postcards (except real photo cards) came off of printing presses. A photographic negative usually was the starting point. Postcard publishers then employed a variety of processes to transfer the image from the photographic negative to a printing surface. On close examination, the finished product reveals expert and sometimes clumsy manipulations that produced the images we treasure today.
Lithography and collotype were the two processes responsible for most picture postcards printed between 1893 and 1920. Collotypes have an artistic finish with delicate lines and tonal gradations similar to an original photograph. Collotype postcards were printed from a gelatin surface that hardened into a network of fine cracks producing the characteristic random arrangement seen under magnification. Many collotypes were hand-colored in soothing pastels or otherworldly fluorescents. Lithography, specifically photo-lithography, was more successful due to cheaper production costs. A magnified photo-lithograph shows a series of dots, produced by separating the image into light and dark areas or different colors with screens. Extremely fine screens could produce a very sharp image. A lithographic postcard might have up to 10 colors due to multiple passes through the press. Some postcards exhibit a combination of collotype and lithography, which created complex and eye-pleasing results.