Archival Tape
For long term storage any of the major professional standard play tapes can be recommended. Although print-through (the tendency of the signal recorded on one layer of tape to imprint itself on adjacent layers) is not the danger on modern polyester tapes that it proved to be on some of the early acetate products, it is best to avoid tapes which have poor print-through characteristics or are of unknown pedigree for preservation copies. In order of their print-through specifications, the following tape brands are all suitable for archive purposes: Racal Zonal Low Print (which has substantially the best print-through characteristics) EMI 816 and 815, Agfa PER525 and PEM468, BASF SPR50LH, Ampex 406, Scotch 262 and Zonal 666.
The tape backing can be of an important feature on archive tapes. Of the products named in the preceding paragraph, Zonal Low Print and EMI 815 have a shiny backing and need to be wound with some care to avoid ridging (or edging) -which makes them vulnerable to physical damage and general unevenness of the tape. The other brands are all tapes which have a textured backing. This gives a smooth even wind even when spooling at high speeds. If archive tapes are liable to fast winding then a textured tape is the best choice. If tapes are always shelved 'end out' after having been wound at a standard recording speed then - even if shiny backed - they will not usually be prone to edging.