Ambrotype portrait from Valentine Studio
Found by chance on the web and purchased for a relatively modest sum from a US dealer, this fine Ambrotype portrait from the studio of James Valentine (1815-1879) makes a particularly interesting addition to the Valentine Collection held by the Library's Department of Special Collections. Not only does it represent an early example of Valentine portrait photography, what makes it especially exciting is that it represents an early type of photography unique in this collection of 400,000 negative and positive images.
So what makes this particular photograph so exciting you might ask? What is an 'Ambrotype' anyway?
Ambrotypes date from 1854 and are often, somewhat confusingly, referred to as 'wet collodian positives' due to the wet collodian process by which they were made.
The process was the invention of English artist and calotypist, Frederick Scott Archer, who, not surprisingly, also invented the Ambrotype. It is essentially a negative image process using a liquid cellulose solution into which photosensitive chemicals are mixed and poured onto glass plates; these are then exposed in camera to produce a negative. Instead of taking the process one step further to produce positive prints, the colloidal side of the negative is blacked, either with paint or by placing on black cloth or paper, to produce a positive image on the plain glass side.
This revolutionary technique mimicked the more expensive French daguerreotype process (an image captured on a silver plate) and was seen as a great improvement on the calotype process which depended on paper supports and lengthy processing by natural sunlight to produce latent negative images and contact prints. The Ambrotype process was far more reliable and faster. The calotype process patented in 1839 produced soft mellow tones but could be hit and miss, with resultant prints prone to fading out. Glass supports gave a more lucid image than paper negatives. Even so, the Ambrotype process was fiddly; photographers had to work quickly to coat and expose the plates before the colloid set. Scott Archer's process overtaken by a dry collodian system, gelatine based emulsions and plastic supports.
A lovely object in itself, and very nice addition to the collection, this portrait of an unidentified sitter has been hand tinted and set into a velvet lined leather case, the lid of which is missing, which no doubt accounts for the scratched surface.
Pam Cranston