Question about DECtape formulation

[Gary Oliver]

On 1/24/22 11:09 AM, Chris Zach via cctalk wrote:
> It sounds more like some sort of sprayed-on coating of some sort of 
> abrasion-resistent material.  It might well be porous, which would be 
> a possible explanation for the oxide coming off when rubbed with solvent.
>>
>>     paul
>>
> Is it possible we're looking at something called "dirt"?
>
> C

Not likely, as it's on all of my  tapes, including the four 'unopened' 
(well, there opened now...) tapes I had in my stash. Brand spanking 
'new' in blue plastic boxes, still with seal on tape.  I even had an 
unused 'scotch' brand that had the seal on the tape, though  that one 
came in a paper box, so conceivably it could have been 'contaminated'.  
But it still looks the same.

Also, in reference to another comment: the 'oxide' isn't coming off 
exactly.  I did have one tape with some really ragged ends on it, and on 
that one, the oxide did flake a bit.  But that tape had other damage on 
the leader end.  For the rest of them (tried so far) all I can say is 
the oxide appeared 'exposed' but on several different tapes I tried 
'scraping' this exposed layer with an exacto knife and all that happened 
is some scratches appeared on the 'overcoat' layer.  No oxide residue on 
the knife.

Sorry if it appears I implied the oxide was degrading.  May on one or 
two, but this is not a feature of the other 100-ish tapes.


I'm guessing it *is* some kind of spray-on 'extra' lubricating coating, 
so I'm just trying to figure out what it is.  Obviously it's extremely 
soluble in iso, but that's the 'strongest' thing I've tried.  As I think 
I mentioned, even water will degrade this layer with some rubbing, but 
alcohol takes it off quickly.  'Dry polishing' the tape doesn't seem to 
degrade the coating, though I do seem some 'smudges' left on the kimwipe.

This issue isn't standing in my way of completing the project - I was 
just checking the 'collective conscience' here if any knew some 
unpublished secrets or where they were published if not secret.

Thanks for all the replies.

-Gary