Stored in direct sunlight for many years - I mean?

On 11/09/2018, CJB <[log in to unmask]> wrote:
> Stored in direct sunlight for many ears?
>
> On 11/09/2018, Tim Gillett <[log in to unmask]> wrote:
>> Hi Peter,
>>
>> Is it possible the tape had been reshelled at some point, or some
>> combination of parts assembled together?
>>
>> Tim Gillett,
>> Perth,
>> Western Australia
>>
>>
>> ----- Original Message -----
>> From: "lists" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Tuesday, September 11, 2018 6:14 AM
>> Subject: [ARSCLIST] very strange/unique decay found on u-matic
>>
>>
>> Today I received a พ" u-matic tape with the strangest damage I have ever
>> seen and was wondering if anyone else had seen something similar or had
>> an
>> idea what might have caused it.
>>
>> We have processed nearly 500, 000 tapes and we do quite a lot of disaster
>> recovery.  I have seen tapes that have been exposed to virtually every
>> negative influence imaginable (and some not so imaginable) so I was quite
>> surprised to see something totally new.
>>
>> The tape:
>>
>> The tape is a 3M UCA-60 from 1984.  The cassette and hubs are white(ish)
>> plastic and the interior posts/guides and the door lock mechanism are
>> made
>> out of black plastic.  The access door is anodized black metal.
>>
>> The damage:
>>
>> The tape is entirely discolored where exposed. The discoloration is only
>> near the edges a few wraps into the tape.  I have not spooled  the entire
>> tape yet to determine how far the discoloration continues.  The metal
>> cassette access door shows many small spots of corrosion on the inside of
>> door where it would be closest to the tape.  There is no corrosion on the
>> outside or the edges of the door. The tops of the metal screws on the
>> back
>> of the cassette are badly corroded.  The entirety of the black plastic
>> tape
>> guides and black plastic door lock mechanism are very brittle/damaged, to
>> the point where they are falling apart and partially missing/destroyed.
>> There is no other indication of damage. The white plastic shell and tape
>> hubs are intact and clean and the plastic slip pads inside the cassette
>> are
>> undamaged.  There is no staining, no warping, no breakage and no
>> brittleness
>> anywhere else. Whatever happened, only the exposed tape and the black
>> plastic tape guides, the black plastic door lock, the inside of the metal
>> access door and the metal screws were affected.  Everything else looks
>> fine.
>>
>> The damage to the tape "could" be consistent with either exposure to
>> liquid
>> or heat,  but-  there is no staining anywhere or damage to the paper
>> label
>> to indicate liquid contamination and there is no brittleness or
>> deformation/melting anywhere else to indicate exposure to high heat.  The
>> overall damage is not really consistent with either liquid or high heat
>> damage. I even considered the unlikely possibility that the tape was
>> contaminated with some corrosive element during playback/rewind and the
>> posts were damaged as the tape was wound into the cassette.  This could
>> explain why plastic guides are nearly destroyed and the metal access door
>> was only corroded inside, near the tape, and nowhere else.  This,
>> unfortunately,  doesn't explain the corrosion on the screws and heavy
>> damage
>> to the plastic door lock mechanism, however, since neither of these parts
>> ever touch the tape.  The plastic hub flange and slip pads inside the
>> cassette, which do contact the tape, are also undamaged.
>>
>> Ok, how about some highly corrosive gas that reacts very aggressively
>> with
>> one specific type of plastic (the guides and door lock mechanism) and
>> uncoated metal (the screws) but doesn't react at all with any of the
>> other
>> plastics in the shell/ hubs/slip pads and/or with anodized metal and
>> reacts
>> differently with the plastics in the tape (or maybe the metal in the
>> tape?)
>> in such a way as to produce a byproduct that corrodes nearby anodized
>> metal
>> (the inside of the cassette door) but dissipates quickly (so the rest of
>> the
>> anodized cassette door is unaffected).  Sound crazy?  Yes it does.  The
>> damage is so very specific and selective that I can't figure out what
>> could
>> have happened.
>>
>> Any ideas?  Magic?  Space aliens?
>>
>> A very perplexed
>>
>>
>> Peter Brothers
>> SPECS BROS., LLC
>> 973-777-5055
>> [log in to unmask]
>> Audio and video restoration and re-mastering since 1983
>>
>>
>>
>>
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>