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@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
