You might look through some of these threads...

I dry-mounted my 16x20 silver gelatin prints due to my presentation method -- print trimmed to image area and dry-mounted in a window one inch bigger than the image area. I like how the edge of the print/image to be defined by itself, not by being over-lapped by the mat board.

Platinum prints and carbon prints I do not dry-mount, but instead hinge-tape from the top to allow the paper to hang flat behind the window. I usually show the rebate with platinum prints.

Galleries and museums like work not to be mounted -- this allows the print to be removed easily if the mat is damaged or the print needs cleaning/restoration.