Question about DECtape formulation

[Chris Zach]

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 at 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
>