Re: [AV Media Matters] Newbie to list question - tape baking, is it wrong?

[Graeme Jaye <gjaye@retemail.es>]

Hi WIll

At 06:02 18/12/99 -0800, you wrote:

>I've got a circa 1982 Ampex 2" 16-track tape that I want to transfer to
>ProTools. It has been stored in various conditions and levels of
>humidity since that time, but has not been played since then. I've been
>told that I'll need to "bake" the tape to keep the acetate from coming off
>on the heads. Is this normal (and is it the only way to do it right?)

This is a well-known problem which affects tape (not only Ampex) of this
vintage.  It is to do with the binder chemistry being changed around that
time for something which (over a period of time) becomes 'sticky'.  It's
commonly known as 'sticky shed syndrome' and it's not the acetate which
comes off, but the iron oxide!!  If I recall, Graham Newton has some
information on his website about this subject
(http://www.audiorestoration.com) which you might like to have a look at.

Baking the tape is the accepted solution for the problem, although it does
*not* effect a permanent cure.  Something like 6-8 hours at 130-140
Farenheit is the usual sort of figure recommended.  I have baked many tapes
(must be well in excess of 100 by now) and have not had a failure so far.
All my tapes have been 1/4" masters, but I don't see that a 2" would be any
different.  It does no harm to leave the tape for longer, but I would be
very wary of going over-temperature.

You can be fancy about it and use a temperature controlled, electric oven
(not a gas one).  Personally, I do mine in a cardboard box, about  2 ft
cube, with the tapes supported on a wooden dish rack, two electric light
bulbs, a dimmer unit and a photographic thermometer :-)

After baking, spool the tape a couple of times before playing.

>This person said that after baking, the tape would only be good for about
>2 to 4 plays, so I want to make sure.

I don't think it is a case of the number of plays, so much as the time it
will take for the binder to re-absorb moisture from the atmosphere (which
is what causes the problem in the first place).  After baking, I place the
reels inside a sealed polythene bag (assuming I am not going to use them
immediately).  They have certainly been playable after a month when treated
this way.

>Aside from the difficulty in finding
>an old 2" machine with a 16-track head (I know you can play them on a
>24-track machine with some level of reliability) - I'm cautious about
>going forward. I'm located in Austin, TX.

I would have thought that many studios still running that type of machine
would have a 16 track headblock as well as a 24 track one - but I'm open to
correction on this point.  You can certainly *play* a 16 track tape using a
24 track block, but some of the tracks are not covered properly and the
head is also partly reading the guard band, which will lower the
signl/noise ratio of course.  I used to know which tracks were which and
the amont of level correction required, but I'm afraid it's a long time
since I last did this and my memory fails me now.

The one thing you should *not* do is to try playing the tape before baking
- apart from the fact of losing a lot of information off the tape, it will
make one heck of a mess of the headblock and guides!!  Otherwise, I would
say this is a reliable method of recovering these tapes.

Graeme Jaye
gjaye@retemail.es

Audio CD stuttering?
DVD dodgy?
CDROM not reading?
PlayStation stationary?
Saturn not flying?

No Problem - Check this out!!!
http://www.personal-cd.com