Or aluminised adhesive tape, such as we used to to put over EPRON windows in the 70s, to prevent accidental erasure by ambient UV light, or even as we put over the notches in floppy disk casings in the same era to make them non-writable.
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
KotPT -- "for stupidity above and beyond the call of duty".