Card Thickness

Early cartes de visite were very thin cards. While most people do not have calipers to measure the small differences, with a little experience, you tell the relative difference by hand. The accepted thickness and usages are:

General Rule:  Thin is pre-1870

Card Corners

This is one of the easiest and most dependable dating techniques. Square corners dominated the cards until 1870. Then rounded corners, much less susceptible to damage were introduced. Caution: Many square cards have been rounded through handling & wear. Look for even, clear edges to decide if it was round or square. Also, some cards were hand trimmed by the owner. These rounded corners are usually detectable due to their uneven trimming
General Rule: Square is pre-1870

General Rule:  Square is pre-1870

Image Size

Early camera & lens technology did not produce large, sharp images. A small picture was much more forgiving. Just as when any new technology is introduced, all photographers did not replace their equipment with the latest cameras at once. Therefore, overlap in dating pictures due to image size can occur. But combined with other features, this can be very helpful. One concept to keep in mind: well-established photographers in large cities are most likely to be on the leading edge of technology

General Rule:  Smaller is older.  Dime size is pre-1865

Borders

While a little riskier to use as a definitive dating technique, it is still worthwhile to know the border styles as they evolved, particularly in the later 1860s and early 1870s. The earliest CDVs had no border. In about 1864 a single thin line, sometimes 2 were used to outline the picture area. In 1866 two lines, a thin inner one, and a thicker outer line became popular. In the early 1870s, much thicker lines came into vogue, and then disappeared again later in the decade.

 

General Rule:  Thin borders pre-1868

Backgrounds

Until the late 1860s the background was either void or consisted of only a chair, small table, or other object which the subject would use to steady themselves. Around 1870 decorative backdrops and props were used. These soon became used to the point of absurdity, but were quite popular.

General Rule: Elaborate props/background is post-1870

TAx Stamps

Tax Revenue Stamps were used to help pay for the Civil War. From Aug. 1864 to Aug 1866 photographs were taxed, requiring stamps be affixed to the photo. This has become a great way to date Civil War era photos.

General Rule: If Stamp is present, picture is from 1864 - 1866