DescriptionA positive photograph on glass
Time Period1850s – 1880s
DetailsPhotograph on glass in metal frame
Dimensions8.5 x 7.25 x 0.5 cm
LocationUCL Cabinet of Obsolete Media
Inventory nºUCL201711

In 1851 the British sculptor Frederick Scott Archer invented the collodion photographic development process, establishing a platform for photographic processes such as the ambrotype and the tintype to follow. Collodion, a thick, syrupy solution made when nitrocellulose is dissolved into alcohol and ether, coats the glass plate which is then bathed in silver nitrate.[1] The plate then becomes light-sensitive so long as it remains wet, lending it the name “wet-plate” process. The wet-plate process is exceptionally quick, particularly because it requires the image to be processed immediately after it was taken, therefore requiring that these photos be taken with a darkroom nearby.

Archer modified this process in 1852 by adding mercuric bromide to whiten the negative produced by the collodion process, creating the ambrotype. This white negative on glass is then backed by black paper or varnish which gives the allusion that the negative is actually a positive. When placed on the black paper the sections of the photograph affected by the mercuric bromide emerge as highlights to the overall dark image. In producing a photograph in such a way the ambrotype behaves in the same manner as a mirror, flipping the image backwards as it renders the left as the right and the right as the left in the same manner as a daguerreotype, lending it the nickname “collodion positive.”

The ambrotype image appears as reflective as the glass itself, differing it from the daguerreotype which is exceptionally reflective. Particularly when the image is produced on a clear plate of glass one can see a separation between the image on the glass and the black backing. The result is an image that can be viewed from all angles and a 3D effect which points to the photograph as being an ambrotype.[2]

The simple process for creating ambrotypes sparked its popularity over the daguerreotype which came before. It is a process that not only required little skill but was also relatively cheap to make, allowing it to become easily accessible for all classes and therefore paving the way for the “democratization of the family album portrait.”[3]

The image produced is relatively fragile, requiring a specific sort of packaging to protect it from breaking or deteriorating. To prevent this chipping or breaking, a “preserver” is created by layering a thin brass matt and a glass cover. The image is then placed in a wallet-like case similar to that of the daguerreotype, often on the right side with a velvet pad on the left. Though its primary function is conservation, this wallet-like format also creates a sense of intimacy with the photograph, alluding to the ability for one to close it up and slip it in a pocket for travel. This feeling of intimacy and nostalgia is embraced by contemporary photographers today such as Sally Mann.


[1] Joe Nickell, Camera Clues: A Handbook for Photographic Investigation (Lexington: University Press of Kentucky: 1994), p. 10.

[2] Christopher James, The Book of Alternative Photographic Processes, third edition (Boston: Cengage Learning, 2016), pp. 422 – 423.

[3] James, p. 418.