Making Magnetic tape

On Fri, Nov 12, 2010 at 6:09 PM, Pontus Pihlgren <pontus at update.uu.se> wrote: I remembered a comment on a list from some time past that 3M could still make it if we ordered enough. I found the post on the archive of alt.sys.pdp8. It is short on information, and probably apocryphal, but the original questioner is of interest. A posting to alt.sys.pdp8 from November, 1998: by "Jay West" Yes. I have perhaps a hundred reels of "Astrotape", an OEM version of DECtape. One reel has been tested by Cam Farnell in Glenburnie, ON; he has a working LAB 8/E with DECtape drive, and he said that it was written in a strange (Astrotape, no doubt) format, but that after formatting as a standard PDP-8 tape, it checked out as good. I haven't got any of my own drives working yet. No, it can't be had, unless we can get a large group together to make a bulk order. 3M once said that they could make new DECtape anytime someone wanted to order in sufficiently large quantities, but we're talking in terms of big quantities, enough to justify a production run. One noteworthy thing about DECtape: It's double-faced sandwich construction. That is, there is plastic on both sides of the oxide layer. As a result, the oxide layer isn't exposed to air, where the binder can oxidize and let it flake off. Old DECtapes should therefore, be very useful except when they've been damaged by reading on poorly adjusted tape drives. The usual mechanism of DECtape failure is wrinkling due to poorly adjusted guides on the tape drive. Typically, the front edge gets stretched and wrinkled, and when it is wrinkled enough, the tape won't stay in alignment through the drive. Doug Jones