Kraft paper is fine, but is used like mount board to protect the boards and the print it may not be "archival" but I have never had issues, in my experience moisture moves into the preheated and dried kraft paper from the slightly higher moisture content of the prints and mat boards. Release paper is "sealed" and does not accept moisture but if you are not properly trimming your print and tissue before tacking it to your mount it will protect your platen from "squeeze out ooze", if your platen is bumpy clean it with platen cleaner. I used to share a press with a guy that used the edge of the platen as a tacking iron, THAT was annoying. Release paper comes in sheets, rolls and boards. All are fine.