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Re: [ARSCLIST] Splice repair

On Saturday, May 03, 2008 9:41 AM, Bob Olhsson wrote:

> The food dehydrator method preserves the condition of 
> tape to tape splices remarkably well. Most splices to 
> paper leader will need to be replaced even if the tape 
> has no sticky-shed problem.

I would agree with Bob here.  We've had very few problems
with splices when using a precision oven (we don't use a
food dehydrator).  A precision oven allows you to control
the temperature within 1-degree Celsius throughout the
entire oven and do controlled temperature ramp up and down
to minimize temperature shock to the tape and eliminates
the possibility of a local hot spot in the oven.

An alternative to baking, if you are concerned about 
baking, would be to use a dessication chamber with a
dessicant like silica gel and let the tapes sit in the
low humidity environment for several days (sometimes I 
need to let tapes sit for as much as 1 month or more).  
Silica gel generally drives the humidity down to about 
30-35%.  There are other more aggressive dessicants that 
can bring the humidity down even lower.  I also keep a 
stirring fan in the chamber to keep the dry air circulating 
in the dessication chamber - a bit like a convection oven.  
Dessication does not always work, but it frequently works 
with early stage sticky shed tapes.  The really gooey tapes 
need to be baked.  If I have a project that has known
sticky shed, I get the tapes well in advance of transfer and
store them in a low humidity (30%) air-conditioned storage 
locker for about a month, and this seems to help quite a bit
by remediating the lighter sticky shed, but the severe 
sticky shed will still need to be dealt with using an oven.

I'm not entirely convinced that baking damages the chemistry
of a tape.  I know this is a controversial statement, but 
I'd like to see some concrete research, not just hypotheses,
as to what is going on when baking.  I believe there is some
research out of Australia that shows perhaps less than a 1 dB 
loss for very high frequencies from baking.  And baking can
certainly aggravate print through (if you do bake, hope that
your tape is tails out).

Eric Jacobs

The Audio Archive, Inc.
T. 408.221.2128
F. 408.549.9867

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