I never dry mount Pt/Pd or gold prints. Prints made from these materials
are amoung the most (if not the most) permanent works on paper, and it
seems counterproductive to do anything to them that has a chance of
lowering their life expectancy.
I either show brush strokes, or mask for clean edges depending on the
clients wishes. Aesthetics aside, showing brush strokes has the
advantage of hiding any slight fogging occuring from degraded ferric
oxalate. I wonder if this has anything to do with the vintage prints
having been trimmed and dry mounted, as the possibility of obtaining
relatively pure ferric oxalate around the turn of the century surely was
more difficult than it is today, and it is difficult today.
I generally, for my own work, mask the edges and print on oversized
paper, as I much prefer this clean look.
There's my $.02
John