By 1862 they become commonplace, and by 1865 they completely eclipse all cased images.
Oh, tintypes are still made in huge numbers, but they are mounted on CDV sized cards, usually with oval holes, so the tintype can be held on back by pasting a slip of paper over them, sometimes imprinted with the photographer's name and address.
The first step in dating 19th century photographs is identifying which technology was used to create the picture.
This is straightforward detective work for most images, but very early photographs can be misleading.
I realize I may be swimming upstream on this minor distinction, but it becomes relevant with cabinet cards and post-1900 matted prints on cabinet card sized mounts.
The last true CDV in our dated images collection is from 1899. They typically measure 4.25 x 6.5 inches (108 x 164 mm).
CLICK ON EACH type to see detailed characteristics.