My theory is there is more degradation product which needs to be 
"evaporated" out or otherwise processed. I don't think anyone has 
definitively described the process to a good deal of satisfaction. Ric 
Bradshaw made it plain to me that he doesn't buy the reversible nature 
of the hydrolysis reaction as described by Bertram and Cuddihy. He 
indicated that it just doesn't happen that way in a filled matrix--the 
chain ends can't find their way back through the other material and join 
up. But we know baking works.

20 °C and 33 % won't fully stop degradation. I do not know what the LoC 
vaults for tape are kept at, but 20 °C is not that cold. 33 % is pretty 
dry. But your tapes are better off than most.

I don't do enough rebakes to know. I have followed Tom's advice for a 
long time. Get a good transfer and be done with it. Ric Bradshaw was 
unequivocal about this as well.

The best reason to keep the original tapes is that we have not recovered 
what Jamie Howarth calls "Mechanical Metadata" from them yet. He's made 
strides towards recovering the mechanical metadata even without 
processing it. There are certainly materials that are worthy of this 
approach. I don't know if there is a business case for this for me or 
other independent restorers.

Cheers,

Richard

On 2013-04-01 5:00 PM, Peoples, Curtis wrote:
> We have stored our tapes for ten years in an environment averaging 68 degrees F and a RH of about 33%.  It used to take 4-6 hours to bake a tape. We are now at 8 hours. I  am interested to know why these tapes are now taking longer.
>
> Curtis
>
> -----Original Message-----
> From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of Tom Fine
> Sent: Monday, April 01, 2013 3:42 PM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] Sticky SHRED
>
> Any theories as to why baking times are increasing?
>
> Also, are you finding you need the longer baking times for re-bakes as well as first-time bakes?
>
> -- Tom Fine
>
>

-- 
Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada                             647 479 2800
http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.