Ozotope was another method that was used beginning in 1898, this was a process that used gelatin silver bromide, which transferred by contact with pigment paper.
Another clue might be the background, and on many the photographers name will be on the bottom of the cabinet card or on the back of the picture.
The paper backing on the photograph can tell the age of some pictures; this includes pictures that have tin that the photograph was placed on.
There are pictures that used daguerreotype, glass plate, cabinet card, and the thickness of the cabinet card can also tell the age of the picture.
While their hair would not be short, the type of bun, bangs or no bangs can provide hints to the age of the photograph.
Men’s hair styles and facial hair is not as easy to decipher the photos age.