The other thing on my mind is, high end audio tape from the same period had a coating to
reduce static electricity. But that would be on the rear side.
On 24 Jan 2022, at 20:09, Chris Zach via cctalk
<cctalk at classiccmp.org> 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