Most photographers would agree that an image, or at least, an image worth saving and exhibiting, should be mounted on archival quality (i.e., acid free) mat board and covered with a window mat to keep the print out of contact with the glass. Usually, for photographs, some shade of white or off-white board is used. Occasionally black or gray is used, but there seems to be general agreement that color can be distracting. Also, most would probably agree that you should be consistent, at least with prints in the same exhibit.
Beyond this, however, there seems to be less agreement. Some permanently mount b&w prints with a heat press while others, believing that reversible methods are more archival , use hinges or corners to mount the prints. I am tending to use corners more and more on prints up to 11 x 14.
Window Size and Placement
Some of those using a heat press to permanently mount prints use a window that is somewhat larger than the image and may leave extra space at the bottom of the image for a signature. (There seems to be no universally accepted method or signing prints either.) Of course, if you use hinges or corners, then the window must cover the edges of the print. While pre-cut mats for an 8 x 10 print often measure 7 1/2 x 9 1/2, I prefer to cover less of the print and usually cut mine about 7/ 3/4 x 9 3/4.
Absolute Center Optical Center
Most of the time I cut the window in the absolute center of the over-mat. However, for smaller images, I sometimes use what has been referred to as "optical center." Placing the window at optical center involves placing it closer to the top than to the bottom. I particularly like this effect with some of my wife's small handtinted prints that are framed to 16 x 20.
Excel File to Calculate Mat Borders
Placing an Image Window at Absolute Center
Placing an Image Window at Optical Center
All Text and Images © Joe Miller, 2003