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Experiencing "sticky shed syndrome?"


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Filed under "restoring a friend's old Korean War era Navy Band recitals." According to the American Chemical Society, reel to reel tape is prone to degradation, which has been a topic of active research for many years. It's well known that applying heat can often reverse the damage sufficiently to enable playback, usually by baking the tapes in an oven. Now scientists at the US Library of Congress have determined precisely why this method seems to work, presenting their findings earlier this month on the American Chemical Society's SciMeetings online platform.  The primary culprit for the degradation is known as "sticky shed syndrome," in which the binders used in a magnetic tape to hold the iron oxide casing to the plastic carrier deteriorate. They form a sticky residue that can damage both the tape and playback equipment. [...] [E]xperiments showed that when a degraded reel-to-reel tape is heated, the sticky residues melt back onto the bulk polymer layer, rendering the tape playable once again. That's why 130F is the sweet spot for baking degraded tapes; it's the melting point for the residues. (This fix, however, only lasts several weeks. Plenty of time to digitize the media.)

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https://m.slashdot.org/story/370234

 

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The 70-80s Ampex 456 is the typical offender I encouter. I was going through some old 70s and 80s cassette tapes last week and all (Maxell, Memorex, TDK, Sony and unbranded) played back fine on my Tascam 122, except to two Ampex. Likely the same 456 type tape stock.

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Scotch 250, and many if not most other high-level low print type formulations that were popular among Nagra users at the time the industry started to shift to DAT etc are affected, badly.  How the tapes were stored matters (very low humidity is good), and all widths are affected.   A few times now I have been handed a 1/4" tape from an earlier period (for instance Scotch 208 and 209 were very popular tapes for Nagra use in the '70s-'80s) and they play fine w/o baking or desiccation.  My archival buds actually don't heat-treat old tapes: they use large fruit desiccators which achieve the same temporary playability but stress the tapes less.

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