My wife, Paula Chamlee, and I trim our prints to the edge and dry mount them. We print 8x10 prints on 8x10 paper.
Printing an 8x10 print on larger than 8x10 paper is a waste of paper.
When mounting or overmatting prints one should never allow the paper base to show through around the edges of the picture. If the paper base is white, it will be the brightest thing visible and will draw the viewer's eye away the picture and be a distraction.
We "float" our photographs in the overmat—leaving about a ¼-inch to 5/16-inch border around the top and sides and a 3/8-inch border on the bottom (to leave room for signing on the mount board).
If we left a white border around the print we would have to overmat right up to the edge of the print. As photographers we are responsible for every square millimeter of the picture space. As such, we see our photographs right up to the edge. Overmatting right up to the edge would be tedious indeed, as we would not want to make the overmat too large (leaving a hairline of paper showing), or too small, which would cover up the 1/16s and even 1/32s of an inch edges of the prints, covering up crucial elements in the picture space—destroying the carefully-seen proportions that were seen on the ground glass.
The matte surface of the mount board and overmat because of its non-reflective surface does not detract the eye from the picture.
If there is a black border around the print, the same consideration applies. We recently had a fellow in our workshop who placed black borders around his prints. His prints were dead. When we covered up the black borders the prints became more alive—as the blacks in his prints began to look black. (Next to his very black borders the blacks in his prints looked gray.)
An exception to this would be the photographs of Richard Avedon. When he photographs people against a white background, the people are centered and the rest of the space is dead space. By leaving in the black border he energizes that space and enables the viewer's eye to navigate the entire picture space and not get stuck only on the figure.
So there are no rules, but whether to leave white or black borders showing when prints are presented is an aesthetic decision—one that must be carefully considered.
Michael A. Smith