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Re: [ARSCLIST] Glass Records

At 11:20 AM 2008-05-28, Marcos Sueiro Bal wrote:
[I think David Lennick wrote:]
And in my experience, glass based discs seem far less prone to palmitic acid.
Interesting statement, and one I had not heard before. We just finished surveying a few lacquer discs (almost all US), so just for fun I tried to run a query.

Of 1,925 with metal substrate, 375 have evidence of palmitic acid (19%). Of 123 glass-based, 22 have evidence of palmitic acid (18%).

"Further research is necessary", as they say ;-)

Hello, Marcos and David,

One of the frustrating observations to fall out of my research on magnetic tape degradation is that there are wide variations in model numbers and even batches of tape. I would not be surprised if the same thing happened with discs. There are even conflicting studies--one says that only chromium dioxide catalyzes certain types of binder degradation while another study says that both chromium dioxide and gamma ferric oxide catalyze a similar type of binder degradation.

From David's? original statement, one could generate a hypothesis to test: does the aluminum substrate act as a catalyst for generating palmitic acid in the lacquer coating? Marcos's survey numbers seem to indicate that the likelihood of this being the case is small. There appears to be no statistical significance between the two numbers.

Yes, more research is needed, but one might consider some confounding factors that might explain David's perception. One that comes to mind is: perhaps since the glass discs were known to be more fragile they were more carefully stored.

Perhaps the best thing to think about here is to schedule preservation reformatting (copying) for all of this fragile media while it's still relatively easy to copy. We now have prioritization tools available in FACET from Indiana University and your tool, Marcos, which should help those responsible for preserving collections to determine the risk of each collection.

The more I learn about tape degradation--and I think some of the same may apply to lacquers as well--the more I see that analog magnetic tape is not a good choice for extremely long-term storage. Fortunately, obtaining high-quality disc reproduction equipment into the future appears to be easier than obtaining equally high-quality tape reproduction equipment.



Richard L. Hess email: richard@xxxxxxxxxxxxxxx
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.

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