introduced a novel method of identifying the year a particular photograph was taken by adding a suffix to the negative number, which was customarily written in ink on the reverse of carte-de-visite portraits.
Each letter of the alphabet represented a particular year of business.
While these light colors were used for many years after, in the 1880s and later various colors were used.
Mounted photographs with multi color mounts and/or embossed designs, particularly an embossed faux frame and photgraphers name, date from after 1890 and usually after 1900.
Very large mounted photographs sometimes do not have the photographers name and address on the front, and the photographic print is sometimes the same size as the mount.
Large, framed and often highly attractive crayon portraits were made in the 1800s and early 1900s.
I've seen 'Celebrities' mount variations with Copyright/Square, Copyright SQ and plain with Square and SQ addresses...
Maybe these mounts were used randomly and there's no relation to dates of production and variations.
The Hyman Collection The Press Photo History Project The correspondence of William Henry Fox Talbot Historic England Archive UAL Photography and Photography and the Archive Research Centre Royal Photographic Society's Historical Group Stereoscopic Company / T. Williams British camera makers and companies Fox Talbot Museum, Lacock.
Best, Jimmy Brett That's a great resource on the LSPC you have created.
I have toyed with the idea of such a listing as I have a lot of their cartes including many of celebrities and also thought of attempting a check list but I have too many other things on the boil and need to focus on those.
If you find an 1892 cabinet card of the Harvard baseball team or 1910 imperial cabinet card showing a high school class there will be no more than a handful of other original copies and it often is unique.
Cabinets depict a wide variety of subjects, including normal families, Presidents and celebrities, animals, buildings, nature and school classes.