tape baking

[Kevin Bowling]

Out of curiosity has anyone tried running tapes at different temperatures,
for instance in a relative cold or hot environment? Either on a simple
winder or even a recovery drive.

On Tue, Apr 28, 2020 at 11:47 AM Chuck Guzis via cctalk <
cctalk at classiccmp.org> wrote:

> I'm a bit surprised that this is even a "thing" in the audio business.
> Restorers have been baking audio tapes for a long time.
>
> One thing not discussed (maybe it doesn't occur in audio) is that there
> can be issues in binder formulation, at least in digital tapes.  In
> particular, 3M tapes, most notably Scotch 701 and 777 formulations, have
> an issue where the binder "liquefies" under motion and solidifies when
> tape motion slows or ceases.  So, you may be running a tape through a
> drive just fine and then suddenly, everything freezes up as the tape
> becomes firmly "glued" to the heads or other objects in the tape path,
> usually with a loud squeal.
>
> In the current batch of 60 tapes from the late 60s-mid 70s, every single
> 3M tape exhibited this behavior.  It didn't matter if they'd been baked
> or not.  There was a note of this on Ed Thelen's site where someone had
> encountered this and given up.
>
> Isopropanol does not clean the sticky deposits from equipment--you must
> use a stronger solvent.  Acetone, Perc or MEK generally does the trick.
>
> Rather than try to clean the gunk off the tape, which is probably a
> fool's errand, I coat the tape with cyclomethicone, using a felt
> applicator in my cleaning machine--it doesn't take much to create a
> slippery film on the tape surface, perhaps 10 ml will do a 2400' tape.
> Cylcomethicone is non-toxic and relatively inert--and is somewhat
> volatile, so that it evaporates in a couple of hours, leaving the tape
> as it was.  Very slippery stuff, so don't spill it on the floor!  It
> does not appear to have a solvent effect on the binder, as nearly as I
> can tell.  It also doesn't appear to bother the equipment either.
>
> I've achieved 100% success using this method.
>
> I think it's interesting that tape quality tends to better the older the
> tape.  Audio Devices, Ampex and IBM Series 500 tapes tend to survive the
> best. Memorex seems to get worse, the younger it is.  (e.g. MRX III
> tends to behave better than MRX V).
>
> For whatever it's worth,
> Chuck
>