Dan Pavel just mentioned in a VDB thread that he marks the area to be coated by making a rectangle with pencil, and erasing it with a rubber eraser after exposing but before processing. I make light pencil marks in the corners of the area I want to coat, and they also help register the negative. I've also noticed that they are harder to remove without damaging the paper surface after any kind of wet processing. But even light pencil marks can be difficult to remove without scuffing the paper surface. What do you do? Does someone have a clever approach that can serve this purpose without leaving any trace on the paper? By the way, a related problem is masking off the paper for coating. I used to use light tack blue painters tape, after pressing it down on a clean wood surface 4 or 5 or 6 times. But even that can damage the paper surface occasionally when it is removed. These days I usually put strips of paper down, taped to a sheet of cardboard beyond the paper edges, not to the paper itself. You can still get nice clean edges that way, and it prevents little splatters in the margins. I'd be curious to know about other ways to mask off areas for coating.