Really?! What's that look like? How did you come
across one?
Do you have photos? :-)
I've seen a few go through ebay. They do show up from time to time and
aren't terribly uncommon.
Nor are they particularly useful.
They are better at contaminating packs than cleaning them.
Visual inspection and cleaning is absolutely essential when working with
20+ year old unknown media.
Yes, that's why I only used it once on analready damaged pack to see how it
works.
Guy's approach is better, and you can see if the pack is usable or not.
Cleaning it with the 'wasching machine' does not allow you to inspect
the surface that well to judge it.
Ed