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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 2nd Jul 2012, 11:11 pm   #1
whyperion
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Default Tape (Mylar) problem.

There are a couple of threads in the past mentioning tape problems.

As I am playing through some prior to sale, as reported the Radio Shack Concertape is a little sticky but seems ok for use. My recorded on (off air Radio 4/Capital Radio economics programme from 1982ish on Shannon Mylar Recording Tape 1mil Dupont Mylar 1/4in x 1800 ft. is shedding its Graphite? all over my deck (I presume I can clean the heads with Meths when it's finally played out).

Also, it has either stretched or it does not wind on so well as it is now falling off the edge of the 8in reel. I suppose I will have to bin the tape and the spool (I have too many empty reels for my need , as the playback is pretty bad and I don't think I can get time to transpose off a good player onto my computer. The tape was stored with all my others, in a generally cool/cold dry room away from direct heat etc.

Anyone got any ideas for salvaging it or do I pronounce dead and bury in garden for future generations to dig up and puzzle over?
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Old 3rd Jul 2012, 6:55 am   #2
brenellic2000
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Default Re: Tape (Mylar) problem.

'Shannon' was Ampex as was Radio Shack's 'Concertape'. Ampex is known to suffer sticky-tape problems - but not all Ampex suffers! The problem lies with the hygroscopic chemical binder which bonds the oxide to the plastic/Mylar/polyester tape (cellulose acetate and PVC doesn't generally suffer this problem). The tape is salvageable by a low bake, only you can decide if it is worth doing.

The spooling problem is unlikely to be due to the tape and suggests poor back tension in fast winding. Polyester/Mylar was designed to stretch before snapping but the tape can't stretch by itself when static on the spool!

Barry
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Old 4th Jul 2012, 12:28 am   #3
whyperion
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Default Re: Tape (Mylar) problem.

The stretching, or loose winding, happened at normal 3 3/1ips forward speed.

Looks like I should have baked the tape before attempting to play it as literally all the magnetic items fell off, leaving a sort of graphite mountain by the capstan and nearly transparent tape.
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Old 4th Jul 2012, 2:37 am   #4
EMI BTR 3
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Default Re: Tape (Mylar) problem.

'Nearly transparent'....meaning you can now see light right through the polyester base film? If that tape now looks the way I imagine it does, it's bad news, and no amount of baking will save the tape. The oxide--and thus the recording itself--has flaked off of the base film.
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Old 4th Jul 2012, 7:52 pm   #5
ben
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Default Re: Tape (Mylar) problem.

Agreed, if oxide is flaking off, this tape has suffered major breakdown. Is it like this?

This is not the same as hydrolisation leading to squealing and sticky residue. Not much can be done to re-adhere the oxide to the backing...
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Old 13th Jul 2012, 10:32 pm   #6
whyperion
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Default Re: Tape (Mylar) problem.

It didn't come off in lumps, but particles like dust. Storage was in its box, horizontally on top of two other boxed tapes, on a shelf in a normally dry cool corner, adjacent to a west facing window but not in direct sunlight. This is approx 2 feet above an electric storage radiator (used only in a few winters and not known to give off much more than 28deg C @ 2ft above it), so hardly excessive storage conditions.
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Old 14th Jul 2012, 7:47 am   #7
brenellic2000
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Default Re: Tape (Mylar) problem.

All tapes lose a bit of oxide (appears as dust) in use through mechanical friction, but your initial report suggested a major loss of oxide and in places a complete loss. This is almost certainly due to the oxide binder drying out and loosing adhesion over 30 odd years.

Any form of dry heat will desciate matter which is why relative humidity is far more important than heat! Make sure the RH in your room/cupboard is around 60% and temperature well under 70deg F (21oC). 28oC is 82oF - that's hot! and will desicate over time.

Tapes should be stored in a cool, dry room to prevent permanent print through, made worse by heat and which is not recoverable. And a final slapped wrist... store spools upright to prevent buckling the flanges - ditto vinyl records.

Barry
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Old 14th Jul 2012, 10:02 pm   #8
whyperion
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Default Re: Tape (Mylar) problem.

Noted

I stored the 7" spools sideways, in their boxes, to prevent tapes from sagging due to gravity (plus the unit I store the few tapes I have is only 6" wide with doors and a open narrower lower shelf).

The smaller reels are upright in the cupboard. The heater has not been on for years, since the cavity insulation and double glazing was fitted the room has not needed it (the storage heaters was none to good at giving much warmth anyway) and winter room heating was achieved by having my dad's Vortexion WVB and the Homebrew valve amp both on in an effort as a teenager to keep a bit warm.
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