RE: arsclist Rejuvenating curled acetate tape

["list" <lists@xxxxxxxxxxxxx>]

>
> "Richard L. Hess" wrote:
>
> >
> > Anyone have any thoughts on a 1976 3M dictation cassette that's
> > squeaking--not sticky shed? It is causing audible scrape flutter in the
> > transfer.
> >
>
> This is purely anecdotal and unscientific but I had an unbranded
> cassette from around 1980 with similar symptoms. I tried playing it in
> various machines over a few days with no joy. I would guess that there
> was a problem with the tape lubricant.
>
> In this case I left it for a few months and when I came back to it the
> tape played perfectly without any problem. Maybe there was a difference
> in humidity or temperature from its previous storage location but there
> were no obvious or major changes.
>
> Unfortunately I would guess that you don't have the time to wait a few
> months.
>
> Cheers.
>
> James.

Here are three possible reasons for James' results:

First, hydrolysis can alter the frictional properties of the tape surface
without actually showing up as obvious "sticky shed"- just sticky, no
tell-tale shed.  If the tapes are left for a few months in a very dry
environment, there can be enough cross-linking on the tape surface to reduce
the "sticky".

Second, if James' first attempts were done shortly after removing the tape
from a cold environment and later attempts were done after the tapes had
warmed up, some crystallized lubricant could have become functional again
(unlikely- this sort of reported result always seems to be anecdotal and not
backed up by testing).

Third, James' later playback could have been done under much higher humidity
conditions.  While high humidity exposure during storage can damage tapes,
during playback high humidity can actually improve transfer characteristics.

Peter Brothers


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