MAGNETIC STOCK BAKING 101 FROM STICKY-TAPE SYNDROME TO A REPEATABLE USABLE PRODUCT
By Bill Henderson
This is a proven method for baking tapes from 35m/m mag. to 2" tape. I instituted this method for audio sound restoration while working for Ascent Media (Deluxe) in Burbank Ca. I used a scientific incubator that delivers a constant heat at a variable rate. We baked hundreds of client tapes with almost a 98% success rate. As theses other articles say, it's the one molecule thickness of water moisture that makes the oxide soft and causes masses amounts of stiction, which ends up stripping off the oxide. As usual, because nothing is 100% perfect we would have the clients sign off on all materials. Baking is the last resort coming close to using vacuum drying chambers to remove the moisture. Used incubators are inexpensive compared to vacuum drying chambers and do a great "repeatable" job!
Leave Reels On Metal Nab Hubs, tapes on plastic reels to be rewound onto metal NAB reels, rewind (slowly) in play reverse for a smooth pack. Preferably with the Head Stack removed. Tape will expand and contract becoming loose on hub. “Do not use hi speed fwd or reverse” Do Not Bake Acetate, Acetate is Brittle and translucent, Polyester is opaque and flexible.
COOKING TIME @ 54 Deg. Celcius (130 Deg. F.
Format
1/4 inch 1 to 4 hours Flip every half hour
1/2 inch 2 to 5 hours Flip every half hour
1 inch 3 to 6 hours Flip every half hour
2 inch 4 to 8 hours Flip every half hour
Note –These are approx., time will vary per condition of tape. Check after first hour, if tape sticks or sheds continue baking. For a first time oven test use an old sticky MRL alignment tape.
Do Not Bake Above 60 deg. “C”
Let tape cool to room temperature in incubator, warm tapes will stretch, make a copy of the tape on the first playing, then work with the copy. Leave master “tails-out” to reduce print-through.
52 deg. “C” = 125 deg. “F”
54 deg. “C” = 130 deg. “F”
57 deg. “C” = 135 deg. “F”
60 deg. “C” = 140 deg. “F”
"I have over 35 years experience dealing with "Shedding, Stiction" and the restoration of all formats from optical to digital"
Good Luck!
Bill Henderson, Motion Picture Sound Engineer, currently at USC School of Cinematic Arts.
htsdesignstudios@gmail.com