Archival plastic enclosures can be made from polyester, polypropylene or polyethylene.
Polyester is the most inert of the three, it can generate static electricity which attracts dust and is more expensive.
Polypropylene is a stiff, high clarity, and chemically stable plastic.
Polyethylene is also chemically stable and although transparent in its low density form, is not as clear as polypropylene.
