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Re: [ARSCLIST] Acetate tape discolours tape box
PVC is not preferred for longterm preservation either, as the
plasticiers break down and get sticky. The C = chlorine, which will
react with the H in air moisture ((H2O) to produce acid HCl. I assume
that the acid detected is hydroclhoric? mild perhaps but there, so we
like to stay neutral or slightly on the basic side with the enclosures
if possible because they can act as a buffer for the inherent acid.
Bev Lambert, Conservator
The Rooms Provincial Archives
St.John's, NL, Canada
>>> arclists@xxxxxxxxxxxxxxx 10/19/2006 1:25:33 PM >>>
Thanks, David, for clarifying that.
One of the other challenges is we've seen A-D strips show acid in PVC
tapes, and don't understand that.
I have seen VS that is bad enough to affect playback and thank
goodness the tapes with it were 30 in/s full-track.
At 11:25 AM 10/19/2006, you wrote:
>Richard, I wouldn't say that they don't work with tape, it's more
>that they are calibrated for film. I'm pretty sure that somebody
>from IPI is on this list (Doug Nishimura?) so maybe they could chime
>in. The AD strips just detect free acidity and they will detect free
>acidity in a tape box just as well as they will in film or in a jar
>of pickles. What makes them useful for film is the color change will
>tell you the point at which the decay becomes autocatalytic so you
>can plan appropriately and deal with the worst stuff first and
>ignore (or freeze or use molecular sieves with) the films with mild
symptoms.
>
>It would be nice to know if the colors were meaningful for tape, but
>I'm not sure what it would tell us. Film has big problems from the
>relatively small amounts of shrinkage found in advanced VS but I've
>never seen (smelled?) VS in tape that was bad enough to affect
playback.
>
>David
>
>Richard L. Hess wrote:
>
>>I have used the A-D strips and have a package, but the general
>>consensus is that they do not work reliably on tapes. I don't
>>recall all of the details that others have observed and someday I
>>will pursue this with IPI, but their focus is film.
>
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.