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-   -   Tape baking gone bad (https://www.acousticguitarforum.com/forums/showthread.php?t=533354)

Bob Womack 01-02-2019 11:17 AM

Tape baking gone bad
 
I've spoken of baking tape on the forum before, HERE and HERE. The basic issue is that tapes are self-destructing and the only way to resurrect them is to literally bake them at low heat (130') for three hours. The fellow who has been doing my baking for me has been having trouble with the fumes from the baking process asphyxiating him so he bought a toaster oven so he could bake the tapes out on his veranda. Here is the result of his first run on a tape with a plastic reel:

http://www.in2guitar.com/images4/badbake.jpg
Lovely, huh? Like that upper flange? I've just transferred the tape. There's lots of creasing and warpage to the tape causing wow. flutter, and scrape flutter. The creasing could be ironed out (if I had the time and this was a priority job) but the warping is causing major vertical mis-tracking across the head stack and I don't know of any way to remedy that. ;)

Bob

Brent Hahn 01-02-2019 11:22 AM

Warping -- as in, the tape used to be straight but now it's curvy, so it slides up and down over the heads? Never heard of that.

Al Acuff 01-02-2019 11:35 AM

AFAIK a convection oven is the correct tool for baking old tape. Thatís what we used when I worked at a mastering facility. Never had a problem.

Bob Womack 01-02-2019 11:36 AM

Yup. Hold the tape up in a line and it looks a little like a snake. I assume it is from contact with the near-molten "fronds" that developed from the upper flange. This is the thinner, long play Ampex 406 tape. I wonder if the thicker, sturdier Ampex 456 mastering tape would have done it?

Incidentally, this about our fiftieth project in the series. That's pretty good odds for rescuing forty year old tape but it's a shame nevertheless.

Bob

Brent Hahn 01-02-2019 12:23 PM

Quote:

Originally Posted by Al Acuff (Post 5936250)
AFAIK a convection oven is the correct tool for baking old tape.

But if you want that savory browning and bubbling, you need the toaster oven if not a full-on broiler.

Edgar Poe 01-02-2019 12:33 PM

Sounds to me like the tapes have been wound too tight and sat too long.
I advise rewinding tapes periodically and wind them slightly loose. If wound too tight, you can also get two problems, layer to layer transfers, and layer to layer adhesion. Neither is good. If you can't push on the edge of the wound tape and compress it slightly, it's too tight. I know smooth wound flat sided reels of tape look cool, but they are not always wound right and can be troublesome.

Ed

Edgar Poe 01-02-2019 12:38 PM

Quote:

Originally Posted by Bob Womack (Post 5936251)
Yup. Hold the tape up in a line and it looks a little like a snake.

Bob

Is this looking on at the flat edge or thin edge of the tape ? If from the thin edge, that can be from being wound too tight. The tape actually stretches, and when relaxed it springs back and causes warp. Which can cause a warble sound.

Ed

Bob Womack 01-02-2019 12:46 PM

Quote:

Originally Posted by Al Acuff (Post 5936250)
AFAIK a convection oven is the correct tool for baking old tape. Thatís what we used when I worked at a mastering facility. Never had a problem.

Yep. I asked the producer in charge to get an air drying oven but he tried this instead.


Bob

Bob Womack 01-02-2019 01:05 PM

Quote:

Originally Posted by Edgar Poe (Post 5936296)
Sounds to me like the tapes have been wound too tight and sat too long.
I advise rewinding tapes periodically and wind them slightly loose. If wound too tight, you can also get two problems, layer to layer transfers, and layer to layer adhesion. Neither is good. If you can't push on the edge of the wound tape and compress it slightly, it's too tight. I know smooth wound flat sided reels of tape look cool, but they are not always wound right and can be troublesome.

Ed

These tapes were wound onto their reels with pack mode, meaning about twice playback speed. The rest of the tapes are nicely packed. Before I play them back, if they are tails out, I rewind them in pack mode to yield a good pack and then play them back. If they are heads I wind them to the end in pack mode and then rewind them in pack mode. In this particular case, when I saw the damage, I chose to pack at playback speed and to record as packing as a precaution.

They also were excised from a tape library after twenty years and thrown away, only to be saved by an obsessive librarian apparently, and chucked into casual storage. Fifteen years later they were offered for archive, and I am getting the results - untouched probably since recorded in 1978.
Quote:

Originally Posted by Edgar Poe (Post 5936310)
Is this looking on at the flat edge or thin edge of the tape ? If from the thin edge, that can be from being wound too tight. The tape actually stretches, and when relaxed it springs back and causes warp. Which can cause a warble sound.

Ed

This is looking at the flat side of the tape, as it passes through the headblock. On this tape only you can actually see the tape move up and down in relation to the vertical plane of the head stack. So there's an actual vertical warp. As I played the spool I could see that the curvatures matched the locations of the globbed upper flange as they relaxed onto the tape. The rest of these tapes have been well-packed and have come to me in good condition.

Honestly, I wish I were working with the Ampex ATR102s I used to work with instead of Sony APR5003s. Due to having all servo motors and a servo lock system they handled tapes better. But these are excellent Sony console professional mastering machines.

Bob


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