Originally posted by Ron Eggers:
Jim Miller must be busy today, or he would surely be telling you that you can use Mylar clear film. I believe him, but I use 1-ply rag.
Hi, Ron. What? Me? Busy? Nah...
Clear film works nicely for edge mounting, especially if you have a big, heavy thing to mount. But thin Japanese paper might be my first choice in most cases.
Clear film and 1-ply (rag) alphacellulose share the same problem: Both are thick, with clean-cut edges. The thickness & cut edges can deboss the art paper if the frame package gets tight from expansion (swelling) during high humidity. So, it's important to avoid fitting the frame tightly.
The lightest Japanese paper would probably be OK for mounting typical paper artworks. And I suggest wet-tearing, to make smooth, tapered edges that can't deboss the art paper.
When edge-mounting, strength usually isn't an issue. Some say the paper should have enough cut/shred resistance to retain the art in event of frame-perimeter impact. Or not -- others say it is better to design in a limiting factor, such as edge mounts that fail, rather than making the art paper buckle under stress. Likewise when hinging, light paper hinges break-away on impact, instead of ripping the art paper.