[ARSCLIST] Baking tapes and high frequencies

["Peter@xxxxxxxxxxxxx" <lists@xxxxxxxxxxxxx>]

Periodically, someone re-emerges with the assertion that baking analog audio
tapes has a negative effect on high frequency reproduction.  Does anyone
have any DATA, or references to actual studies, that support this claim or
other claims that baking tapes has serious negative effects?

I have, of course, seen circumstances where baking has damaged tapes.  Most
of these have been where individuals have not applied the technique properly
and have baked acetate tape (yipes!) or baked tapes in their kitchen ovens
at way too high and uncontrolled temperatures.

Baking can sometimes cause damage if the tape is seriously cinched or
contaminated and is not re-packed or decontaminated before the baking is
done.  I have also seen data that baking can cause changes in the tape
surface visible under an electron microscope.  This data, however, was
obtained by "baking" the tape at a significantly higher temperature than is
recommended by the AMPEX procedure.

Certainly, one might expect that baking could have an effect on the
low-coercivity, "thermal idiot" recording pigments found scattered in most
early audio tape pigment mixes.  These, however, should also be expected to
be the same low-coercivity pigments that are randomized by the "mechanical
shock" used during the wind/rewind often employed to reduce print-through.

Baking is not the panacea for all tape problems.  It has, however, been used
successfully for years all around the world to deal with binder hydrolysis
problems (sticky shed).

Is there any data out there that supports the claim that it degrades the
signal reproduction on analog audio tape?  I have been on the AES, ANSI,
SMPTE and ISO technical commissions for tape preservation and, to date, have
never seen any supporting data for the claim.

There are other methods to treat binder hydrolysis.  They are much more
time-consuming and a pain-in-the-#&$.  If there is evidence that "baking"
damages part of the recording, it would be helpful if someone could produce
some data.

Any comments or data to share?


Peter Brothers