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Photochrom Images
Archives and Art Collections

The Photochrom Process and Collections

The Photochrom was a photomechanical technique that was invented and patented by PhotoGlob AG of Zurich, Switzerland in the late 1880s. The word was Americanized to Photochrome by The Detroit Photographic Company which obtained exclusive ownership and rights to the process in America in 1897.

The Photochrom Process

Photochroms were made by a photomechanical process using multiple lithographic stones. A separate lithographic stone was required for each color in the final print. A minimum of four stones were used for each print, and occasionally as many as fourteen stones were used. This process permitted the mass production of color postcards, prints, and albums for sale to the American market.

The stones used by the Detroit Photographic Company were imported from Bavaria and coated with a special Syrian 'asphaltum' substance that would be chemically sensitized to light, put in contact with a photographic negative, exposed to the sun for up to several hours, then "developed" in oils of turpentine.

The areas of the very thin asphalt gel most exposed to light would harden, becoming insoluble; the less exposed residue would be washed away. Tonal values of the remaining positive image could be manipulated by varying the chemistry and development times. Technicians could do the equivalent of burning and dodging by retouching the brush and polishing with fine pumice powder. The final steps in preparing the stone were an acid etch to bond the remaining image with its very fine grain, and a glycerin bath.

A separate stone would be made for each color to be used. A minimum of four stones and as many as fourteen stones might be used for a given image. A transparent ink would be applied to the stone, then transferred to high-quality paper whose texture resembled the smooth photographic printing paper of the day.

The final steps was a varnish which gave each print added depth and richness. Because the process involved a number of crafts people and because the stones had to be re-ground occassionally substantial variations may be noted between different editions of the same image over the years.

The process "re-developed" the image into stunning full color image that looks more like a painting than a photograph. While not exact, they produced striking images considering the technology of the time.

The Library of Congress Collection

The Henry Ford Museum & Greenfield Village (Dearborn, Michigan) has one part of the collection of negatives and prints from the Detroit Publishing Company - approximately 18,000 vintage photographs, 9,500 postcards, and 2,500 Photochrom prints.The other collection is now housed by the United States Library of Congress, which received them via the Edison Institute and the Colorado Historical Society in 1949.

The collection at the Library of Congress has about 28,000 images available - 25,000 negatives, 20,000 photographic prints, and 2,900 transparencies dating from 1880s to 1930 which come from the Detroit Publishing Company collection. The Library also has 5,930 Photochrom images ca. 1890-1905 which are accessible online, approximately 5,000 of which are attributable to the Detroit Publishing Company. These are in the form of reproductions that were derived from Photochrom lithographs that are over 100 years old and which have a range of minor defects ranging from graininess to discolorations that are attributed to the original. Most of the photochrom images are visible in digital form at the Library's web site in the Prints and Photographs Online Catalog and can be accessed via the Photochrom Prints Search.

In producing the Library of Congress' electronic version of their collection, an effort was made to recognize the role of individual photographers and companies represented in the Detroit Publishing Company. Information was gathered from various sources including the negative logbooks held at the Colorado Historical Society and information on the glass negatives themselves. Many negatives were attributed to William Henry Jackson based on these sources, and on information contained in the Detroit Photographic Company catalog of 1898. Since attributions could not be determined for every image, researchers may wish to contact the Colorado Historical Society for information concerning specific images.

The images include landscapes, seascapes, storms, boats, mountains, lakes, rivers, and cities from the United States and Europe and includes Germany, France, Italy, Scotland and other countries. Structures and sites that are depicted include bridges; churches; hotels; government buildings; lakes; mountains; museums; monuments; public gardens; and resorts. Street views, cityscapes, landscapes, and waterfronts are also represented.

The Library also has a collection of 591 photomechanical prints from the PhotoGlob Co. of Zurich, Switzerland, the inventor of the Photochrom technique. The countries that are depicted include Austria, Bosnia & Hercegovina; Croatia; the Czech Republic; Hungary; Italy; Poland; Romania; Slovakia; and Slovenia.

Note:  It is not known at this time whether the PhotoGlob Photochrom images are publicly accessible. [They may be consolidated into the 5,930-image collection of Photochroms that are available online and which are attributed to the Detroit Publishing Co.]

The Library of Congress Photochrom prints acquired from the Detroit Publishing Co. and others can be viewed online at:

Our Collection

Because of their historical as well as artistic value, the Photochrom images that we acquired from the Library of Congress for our collection include not only Istria and its surrounding regions, but also Carniola, Venice and Dalmatia.

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Created: Sunday, August 17, 2003, Last Updated: Wednesday, February 13, 2008
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