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Hi, Allison, The Ampex patent recommends both 50 and 54 °C (122 and 129 °F) and I try to hit the middle of that range using the thermocouple. Having 8 tapes in the dehydrator may increase the length of baking required, but the 1/2-inch tapes that failed to recover at 24 hours was one particular batch and I did not know their storage history. I do find that less than 24 hours is often problematic with tapes I get in to transfer, so just running 1/4 inch tapes about 24 hours seems safe. There is a much greater risk from pulling mag coat off if the baking is under-done (or not done at all) than any damage that the baking at these temperatures may cause (which, so far, I think is none). I used to play a bit with the time-temperature ratio, but do not now. The one time I baked a set of tapes a second time, it did not appear to be an issue, although others have reported being less lucky. Cheers, Richard On 2014-02-24 10:31 AM, Smith, Allison wrote: > Hello and thanks to everyone who has responded so far to my post - > > I'm intrigued by the dehydrator solution. Richard, could you tell me > what temperature you are setting the Nesco unit to, when you bake 24 > - 48 hours? Is it the lowest setting? If so, I'm wondering if the > dehumidification process is less stressful / radical than traditional > convection oven heating (higher temp for a shorter period of time) - > letting the tape layers relax into place more naturally/gently? Or, > does this matter? Anyone done a study? > > For those of you using the dehydrating solution - do you have a > temperature/time ratio that you generally use, that you would share? > Will you tell me the model you are using, with the temp/time? > > How have your tapes held up post - dehumidification? Is it similar > to baking - where you only get a few plays before the tape needs > processing again? Will they bake again if necessary? > > Thanks so much - > > Allison > > *********************************************************** Allison > A. Smith Archivist, Wisconsin Public Radio 821 University Avenue, > Suite 7151 Madison, WI 53706-1497 P (608) 263-8806 F (608) > 263-9763 [log in to unmask] It's not true I had nothing on, I had > the radio on - Marilyn Monroe > > *********************************************************** > > > -----Original Message----- From: Association for Recorded Sound > Discussion List [mailto:[log in to unmask]] On Behalf Of > Richard L. Hess Sent: Friday, February 21, 2014 04:52 PM To: > [log in to unmask] Subject: Re: [ARSCLIST] Recommendations - > Convection ovens for baking tapes > > Hello, Allison, > > Many of us use the American Harvest food dehydrators from Nesco. I > have had and used the same one for over 10 years and it still checks > out OK. I would suggest checking the temperature dial from time to > time with a nice thermocouple thermometer, especially since the > out-of-factory calibration could be better, but the stability is > about in a 2 °C window which should be fine. The fast airflow removes > the moisture and other volatile products, though a white filter over > the air outlet has never become discoloured in my testing. > > I would, however, recommend using this with outside exhaust in a > commercial application due to the possibility of someone saying they > got sick because of it...stranger things have happened. > > I like this as each 10.5-inch reel fits on its own slotted shelf, no > spacers required. > > The convert-a-tray shelves remove for laying in non-NAB hub reels. > > I have both the older unit with the fan in the base and this one. > This one is my "moldy" machine which is kept in the garage for tapes > that I do not want to contaminate my main one with. These URLs may > get split... > > http://www.nesco.com/products/Dehydrators/Dehydrators/FD-60-Snackmaster-Express-Food-Dehydrator/ > > Also available in gray > > http://www.nesco.com/products/Dehydrators/Dehydrators/FD-61-Snackmaster-Encore-Food-Dehydrator/ > > convert-a-tray kits: > > http://www.nesco.com/products/Dehydrators/Add-a-Trays/Convert-A-Tray-Set-of-2-White/ > > > http://www.nesco.com/products/Dehydrators/Add-a-Trays/Convert-A-Tray-Set-of-2-Speckled/ > > These will take reels up to 12.5 inches in diameter. > > If you have 14-inch reels, the large one takes the tape pack but is > about 1/4-inch shy for the flanges... > > http://www.nesco.com/products/Dehydrators/Dehydrators/FD-1010/ > > and the add-a-trays to allow baking 1" tape--these are not adaptable, > so I cut out the inner screen on four trays, making them just rings. > > http://www.nesco.com/products/Dehydrators/Add-a-Trays/Add-A-Tray-FD-1000-1010-1020-1040-Set-of-2-White-15-1-2/ > > I have probably processed over 1000 reels of tapes through my > various dehydrators and all have worked well. In one month, I ran 114 > 10.5 inch reels of 1/2-inch tape, each tape being baked for 48 hours > because a 24-hour bake was not enough. One reel was sent back for > re-baking and ran through four 48-hour cycles and then played > fine...it was Scotch 226, the others were all Ampex 406, if I recall > correctly. > > I used the large oven to bake about a dozen instrumentation tapes > containing seismometer signals of the Mount St. Helens volcanic > eruption from 1980 and a few 14-inch reel master tapes. > > Obviously, many of the other scientific and production tools > mentioned are fine, too. These are a very inexpensive, small, and > fit-almost-anywhere solution that I and others have used with great > success and no reported damage. > > Cheers, > > Richard > > > > On 2014-02-21 11:36 AM, Smith, Allison wrote: >> Hello ARSC members - >> >> We are in the market to purchase a new convection oven for baking >> tapes with sticky shed. While we realize there are other methods >> for dealing with this issue and are exploring them, we have to work >> within a budget and timeframe that requires baking. >> >> The oven we currently use is not very good at accurately regulating >> an even temperature, so, we are looking at some of the professional >> brands, which can get quite expensive. Can anyone recommend what >> they are using, and let me know the make / model? >> >> Thanks! >> >> Allison > -- 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. > -- 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.