One can be really cautious when buying a calibration tape… nothing wrong with that. But that will also preclude buying a used MRL tape of any date, including 2007. The only way to really know any tape’s history is to buy it from someone that knows its history that you can trust, or to buy it yourself new. Ideally we should buy everything new, but in the real world of guerilla recording we work with what we have.
If you have owned a tape for years and just pulled it off the shelf to find it has sticky shed (or you’re worried it might) baking does truly restore a tape at the molecular level. The problem is it usually will get sticky again. The time it takes depends on the relative humidity of your environment. The good news is that you can bake a tape as many times as you need.
In a home/project studio you might check alignment once a year, and even then not have to adjust anything.
If you already have a tape then go ahead and bake it using the prescribed method in the following link. (not every word on this site is accurate, but the baking method is sound)
http://www.tangible-technology.com/tape/baking1.html
A properly maintained machine will tell you if the tape is any good, because when you run it you’ll see it’s already on. That’s how I tested the old 1978 MRL tape after I baked it. My machine was already in perfect alignment with a newer MRL tape (had been for 2 years).
If a tape has been damaged by a magnetic field it will be markedly down in dB from 0 VU by the same amount on every track @ 16 kHz and above. First you run the 1 kHz tone to check that it is at 0 VU. It will take a lot more than a typical magnetized tape path to impact 1 kHz. After you’ve established that 1 kHz is ok, you run 16 kHz or 20 kHz (whatever your instructions require). It should be within the machine’s specifications. At 16 kHz it might be 0 VU or be up or down a dB or two… depending on the machine’s tolerances.
I strongly recommend against buying blank or used tape from the sticky shed years to record with, but if you already have a calibration tape this is one area where baking can be useful. Dehydrating within the recommended temperatures has no adverse effect on tape or the recorded material on it.
-New 1” MRL calibration tape; $260.00 to $470.00 (depending on which one you need)
-Snackmaster dehydrator at Wal-mart: $39.96 – $44.88 (or similar model)
Sticky shed is indeed a mess if untreated. I won’t even play a backcoated tape made before 1995 before baking it. Each person has to consider their calibration tape on a case-by-case basis.