I lost the original thread in the chaos of my computer, but in any event my point applies to all media, wherever you want the edge to show, or think you might ever... I was waiting for someone to mention the way we were taught (eons ago) to simulate a deckle edge...
Put a ruler or straight edge of some kind or other where you want to cut/tear, or simply a light pencil line, and draw a brush loaded with water along it at intervals until it has totally saturated the line. Then tear at that point against a hard edge ruler -- or whatever. If you've been patient enough for the line to get saturated (time depending on the paper & its thickness) you'll get a pretty fair facsimile of the deckle edge.