There’s no doubt about it, a dry-mounted print is the flattest. It was Ansel’s style to mount prints – in fact at the time it was THE way to “properly” present a print. Many people still prefer to mount their prints – when it’s well done and overmatted it looks terrific. The downside is that if the mount becomes damaged or soiled, it kind of wrecks the print. Further, if a slipsheet, fingernail or other object happens to catch the edge of the mounted photo paper it can tear the emulsion away, again wrecking the print. Lastly, the museum world and many serious collectors prefer unmounted prints. For storage as well as archival considerations. Museum archivists feel that the print should not be attached to any foreign material – and an unmounted print is much easier to store! Another camp feels that the mount tissue itself acts as a barrier, protecting the back of the print from exposure to deteriorating gasses.
I quit drymounting prints sometime in the mid 1980’s, or at least I stopped mounting them in the conventional fashion. I print with a minimum of a 1″ margin between the image and the edge of the paper. Prints 11×14 and smaller I don’t mount at all. I flatten the air-dried prints in a mount press and then put them in a presentation/handling mat. A properly sized bevel overmat is hinged to a backing board, and the print is then positioned in the window and then corner-mounted to the backing. 16×20 and 20×24 prints are mounted onto a sheet of 2-ply museum board to stiffen the print and make it flatter, but they are corner-mounted in a handling mat in much the same manner as the smaller prints.
Anecdotally, I’d like to note that I have been called upon to restore several Adams prints, which had become partially or entirely separated from the original mount board. I have had to carefully remount the prints to the original, sometimes damaged or foxed board because Ansel’s signature was on the mount! Additionally, I had several prints come back, from a gallery that should know better, with wine stains on the mats and backing! The prints themselves were fine, so I just put them in new mats!