I believe that data was at room temperature. Baking accelerates that.
On 2015-04-07 7:34 PM, John Chester wrote:
> On 4/7/15 5:26 PM, Richard L. Hess wrote:
>> On 2015-04-07 3:18 PM, Eric Jacobs wrote:
>>> 2-inch tapes with sticky shed may not respond as well to baking as
>> That is true in the sense of in the same or similar time frame.
>> I don't think there are precise formulae for predicting the time
>> either to achieve thermal equilibrium or to achieve moisture
>> equilibrium in a tape pack. Vos (1994) inspired me to develop a rule
>> of thumb that moisture equilibrium appears to take 1500 times as long
>> as thermal equilibrium in a one-inch tape, based on my extrapolations
>> from his curves.
>> We have long suspected that the width of the tape was a large modifier
>> of this ratio. I based my estaimate on Vos's graphs which seemed to
>> indicate that a 1-inch tape pack, might achieve thermal equilibrium
>> might in 100-200 minutes while it might take 100-200 DAYS to achieve
>> moisture equilibrium. I felt that a factor of 1440 implied far too
>> much precision in the calculation, so I rounded it to 1500.
> 100 days to achieve moisture equilibrium? That must not be required for
> curing sticky-shed audio tapes, because they don't need to be baked
> anywhere near that long. I recently asked Steve Puntolillo (who
> regularly bakes 2" audio tape) how long he baked it. He said he gets
> clean playback on most 2" sticky-shed tapes after baking for 2 days, and
> cooling and resting for 1 day. My recent experience with 1/4" Ampex 407
> is that one day bake and one day cool and rest is almost always
> adequate. However, both Steve and I have observed that the required
> bake time has about doubled compared to a few years ago.
> -- John Chester
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada 647 479 2800
Quality tape transfers -- even from hard-to-play tapes.