Question about DECtape formulation

Gary Oliver go at
Mon Jan 24 21:27:35 CST 2022

On 1/24/22 4:25 PM, David Gesswein via cctech wrote:
> On Sun, Jan 23, 2022 at 03:09:53PM -0800, Gary Oliver wrote:
>> Taking the bits of tape, I exposed them to various concentrations of
>> isopropanol/water (from about 25% to 99% iso) and found than in all cases,
>> some of the data side of the tape came off on the wipe.? The remaining tape
>> fragment appears intact - the brown oxide was still there but both sides
>> were now the same color, rather than the data side being darker (as were all
>> my tapes before the test.)
> I had done the careful test to find something safe to clean DECtape. One
> time I grabbed the wrong bottle and that removed the coating. Tape was now
> totally unreadable in that location. Didn't have any luck with cleaning
> helping data errors so stopped trying. This was a long time ago so I don't
> remember if my incorrect cleaning result matched your description.

As to the real reason I was doing this: Most of my tapes are un-boxed 
and have suffered being in a dusty area (before I got them) with the 
dust forming a sort of 'crust' on the outside of the tape.  It's only on 
the first wrap or so, but it's enough that it keeps those handy vinyl 
cohesive tapes from sticking.  For that reason, I was trying to find 
something to clean of this dusty gunk so the vinyl strip would hold the 
tape into a spooled condition. It was the side-effect of this effort 
that lead me to the discovery if this "removable layer" on the DECtape.

BTW, does anyone know of a source for these vinyl strips.  My old ones 
are 10 mil blue very-flexible vinyl without any adhesive. They rely only 
on the cohesive properties of vinyl-to-a-non-porous surface.  I tried 
using some of the 'dry vinyl' sheets from Cricut (the plastic decal 
printer company.)  They have a couple of colors without adhesive that 
they call "window cling" but they aree only 4 mills thick and a bit 
flimsy, though so-far they are holding ok.



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