As experienced conservation framers in a previous life, we are fully aware of the methods and materials necessary for optimum preservation of these often very fragile works.
All our leaves are matted in museum-quality rag board. The foam board we use for backing some items has facing papers made of pure natural white cotton fibres, bonded to a chemically inert, non-acidic core.
We never attach hinges to a leaf, but rather use acid-free Mylar corners to hold it in place within the mat. This method also allows the leaf to be easily and safely removed from the mat. We recommend using conservators' cotton gloves when handling the leaf.
We strongly recommend using UV-blocking conservation glass or acrylic when framing. If you don't have a framer that you have full confidence in, we suggest asking institutions that require their rare and valuable items conserved/framed - the NGA, NGV, State Museums, State Libraries, university libraries etc.
The AICCM (Australian Institute for the Conservation of Cultural Materials) may also be able to point you in the right direction.