RE: Question about DECtape formulation
> On Jan 24, 2022, at 10:27 PM, Gary Oliver via cctech wrote: > >> ... > > 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. > I talked to a friend who was at DEC during the days of DECTape and thereafter, his comment: ..."I think it is a thin version of the base material, some flavor of polyester film. Most likely a 3M tape. The bit density is so low a little spacing doesn't matter much. ...The UNISERVO I, of Univac I, tape drives had a separate spool of clear very thin film that was clock motor wound across the head when tape was moving, since the phosphor bronze plated tape was very abrasive. That existed long before LINCtape/DECtape." Note that LINCtape is DECtape :-) Tom
Re: Question about DECtape formulation
> On Jan 24, 2022, at 10:27 PM, Gary Oliver via cctech > wrote: > >> ... > > 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. There's a children's toy I remember: shapes cut from vinyl, intended to be stuck to windows to make pictures. That seems to be the same stuff. paul
Re: Question about DECtape formulation
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. -Gary -- -Gary
Re: Question about DECtape formulation
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.
