Historical artifacts deserve optimal foam archiving so that everything is preserved for future generations.
Only acid-free and plasticizer-free plastic products should be used for the packaging of art objects. In general, chloride compounds (e.g. PVC) should not be used. Products made of polyethylene terephthalate (e.g. Mylar), polyethylene (e.g. Dibond), polycarbonate (e.g. Lexan, Tuffak or Makrolon), polymethyl methacrylate (e.g. Lucite, Plexiglas or Perspex) and polypropylene are suitable. Polyester, polystyrene and silicones are less useful, as the latter give off acetic acid, especially during drying.
Among the foams, physically foamed low-pressure polyethylene foams (e.g. Ethafoam, Plastazote) are harmless, provided they are not coated with adhesive strips. It should be noted that they are not hygroscopic (non-water-absorbent).