Help can be given to identify a process but the following may be useful:
The end dates of a photographic style are approximate and cover the most popular period for production of the particular process.
DAGUERROTYPE: 1839-1855 The first commercially patented photograph formed on the sensitized surface of a copper plate. Usually encased in a soft (pinchbeck) metal case and housed in a papièr mache case. A one-off process. A number survive.
CALOTYPE: 1841-1850 The first negative/positive process. Very rare.
AMBROTYPE: 1851 A negative on glass, turned into a positive image by coating the back of the glass with black shellac or velvet. Very often hand coloured. Housed in a similar way to daguerreotypes. Many survive.
OPALTYPES: 1865 – 1900 A photograph exposed onto a sensitized glass surface. The glass would have a milky white opalescent appearance. Fragile and surface very susceptible to being scratched.
TINTYPES: 1860 – early 1900’s (Ferrotype) A photograph printed on a thin blackened sheet of iron. An in -camera process for the itinerant photographer. Up to 36 exposures on one plate and cut up and given to the customer while still wet.
CARTE DE VISITE: 1855 – 1860 but many evident until the early 1900s. Visiting card size – Popular with the aristocracy and vastly cheaper than its predecessors. The photograph would be mounted on a high quality card, usually showing the name of the photographer on the front.
CABINET CARD: 1866 – 1885 Print usually about 4” x 5” and mounted on high quality card with a finished size of about 4 ½” x 6 ½ “, again with details of the photograph on the front. Earlier cabinet cards with square corners, later ones have rounded corners and often very ornate backs with further details of the photographer. Dark card used later.
POSTCARDS: 1894 onwards. Many portraits printed on this format and therefore not mass produced but divided back not introduced until 1902 when more landscapes and hence larger numbers made available for posting.
PAT: PHOTOGRAPHIC ACTIVITY TEST: The Photographic Activity Test, or PAT, is an international standard test for evaluating photo-storage and display products to ascertain interactions between photographic images and the enclosures in which they are stored.
Manufacturers can use the word “archival” in their advertising regardless of the quality of their product. However, most manufacturers are dedicated to producing quality products for the storage of photographic materials. The PAT is the best indication that materials have been manufactured to worldwide standards.
V-MOUNTS: Clear museum grade polyester with acrylic adhesive strip
Trim to suit your needs securing item safely in place with a strip on edges as appropriate.
POLYESTER SLEEVES: Polyester sleeves contain none of the harmful pasticisers found in plastic and vinyl sleeves. They are totally inert, chemically stable, crystal clear and pass the PAT Photographic Activity Test. They will not yellow or become brittle with age.