I am making masks out of tree bark collected from dead wood. For one of the masks, I thought it would look nice to add leaves to it for a sort of Green Man look. I am trying to maintain a plausible periodicity to the project - that is, I'm not using anything that would be completely unobtainable to a relatively primitive tech level, but I'm willing to cheat and update the technique - so, since glue can be made pretty easily, I am using glue, but I'm willing to use epoxy and modern carpenter's glue.
I'm looking for a way to preserve some green leaves to attach them to the mask, so that they won't crumble from drying out as they would if I left them untreated. neeuqdrazil has suggested wax, which might work (ironing between wax paper sheets, for example), but I am curious to find out what other people think of as possible methods. And so I turn again to you, LazyWeb, for your advice.