They are safe for use in constructing tightly sealed environments providing good protection against externally generated pollutants and variations in external humidity.
Glass and other vitreous systems
Rigid plastic materials such as acrylics (Perspex™, Plexiglas™) and polycarbonates (Makrolon™). Unplasticized polyvinyl chloride (uPVC) structures are also likely to be stable for the periods in question although there is a small risk of the emission of HCl over longer time periods
Unbleached, undyed cotton
Acid free paper and card (“archival quality”)
Metals – but beware of the possible problems due to electrode potentials between different metals
Powder coated metals (if appropriately baked)
Alcoxy (non-corrosive, alcohol curing) silicones
Silica gel
Polyester films (Mylar™ D, Melinex™, etc.)
Polyethylene, polypropylene, and other “virgin grade” polymer films not containing plasticizers etc
Carboxy methylcellulose adhesive.