RESTORATION

When baked, the tape will expand and become loose around the hub. For this reason, use flanges to protect the tape from coming apart. Cooking temperature is between 130°F and 140°F. Tapes wound on plastic reels with small hubs should be rewound onto large reels with NAB hubs. Be careful to thread the tape around the hub without any "folds." The goal is to minimize "mechanical distortions" that can be impressed upon subsequent layers causing dropouts. The "wind" must be smooth as if played!!!

I have received several e-mails regarding "cooking time" and temperature.  Provided the wind is smooth, I am not afraid to bake a quarter inch tape at 135°F — for two hours — flipping every half-hour.  You will find that cooking time varies with tape width, type, brand, condition and the number of reels being baked.  Ampex tape from the seventies might require twice as much time as 3M tape from the eighties (as reported by Wendy Carlos when restoring her masters from that time period).  Table One below can be used as a guide.
 
 

Tape Width

Baking Time varies with temperature and condition

Comments

(applies to all)

1/4"

1 hour to 4 hours

Position near top cover and flip every half-hour

1/2"

2 hours to 5 hours

Assuming "tail-wind," play backwards after wrapping cloth over heads.

1"

3 hours to 6 hours

Check for splices and shed

2"

4 hours to 8 hours

Bake 1/2 hour for each 1/4-inch,
flip every 30 ~ 60 minutes.

Table One: Recommended baking Time and Tips based on temperatures ranging from 130°F to 140°F.


If you are conservative about time and temperature and the tape still sheds after baking, put it back in!  Being conservative for the sake of not losing high frequencies is a bit silly.  Shedding during a transfer can be annoying at best and a pain-in-the-ass if you don't discover the flaw until way after the time of transfer.  If you are concerned, consider baking a tone reel or test tape for evaluation purposes.  Test tapes are not immune to shedding.  Based on my experience, tapes can be baked more than once.  Afterwards, return the tape to its box, allowing it cool for the same amount of time it was baked as a precautionary measure.  Not all machines are equally gentle, a warm tape is more likely to stretch than one at "normal" temperature.