Photographic Processes: 1839 – 1889

WET PLATE COLLODION

AMBROTYPE, 1855-1865

Silver-based, one-of-a-kind image on a glass plate with collodion as the binder to hold light sensitive materials

An ambrotype is essentially a collodion negative that is underexposed. The underexposed collodion has a creamy image tone. When placed against a dark background, the creamy image appears as the light tones of the positive image. The area without image particle (i.e. clear in the negative) shows the dark background and becomes the dark tones of the positive image. The black background is created in a variety of ways including coating the back of the glass with black lacquer, laying the glass on a piece of black fabric, or using dark glass, often called "ruby glass," instead of clear glass. As with collodion negatives, ambrotypes are often coated with a protective varnish.

Like a daguerreotype, an ambrotype is usually encased. Unlike a daguerreotype, it remains a positive image under all viewing angles.

Mathew Brady. Ambrotype, late 1850s. [zoom]
Quarter plate
Additional images:

The ambrotype process produces a collodion glass negative which, when viewed against a dark background, creates the appearance of a positive image. When viewed against a light background, however, the image is revealed as a negative.

Degraded Ambrotype, ca. 1860. [zoom]

Previous Section | Next Section