One way to tell is to do an independent test. I have a ton of Dectape,
including some stuff that is probably psychological data from 50 years ago.
So what are the exact steps, I'll replicate on some LincTapes and report
back.
C
On 1/24/2022 10:30 AM, Paul Koning via cctalk wrote:
On Jan 23, 2022, at 8:40 PM, Noel Chiappa via cctalk <cctalk@classiccmp.org>
wrote:
From: Gary Oliver
I've always thought the physical tape wound on a DECtape spool was a
fairly conventional 'sandwich' of mylar/oxide/mylar ...
Was there some kind of 'lubricating' coat on the data side? It makes
sense, but none of my DEC documents or Googling has any mention of
lubrication ...
If someone has some detail information on the tape construction, I'd am
curious to see it.
Dunno if you know of this:
http://www.bitsavers.org/pdf/dec/dectape/3M_DECtape_Spec_Nov66.pdf
but it doesn't mention any lubrication, just a "Protective Overlay" layer,
over the "Coating" (which I assume is the oxide). I'm a bit surprised that
"some of the data side of the tape came off on the wipe", though, unless the
"various concentrations of isopropanol/water" dissolved the Protective
Overlay.
Noel
Depending on how much the tape has been used, it's possible that the top layer
has worn through. I have known that to happen on highly used tapes, though not
many got enough to wear that far.
It also might be oxide tranferred from one tape to the head to other tapes, if
the heads weren't cleaned enough.
paul
