[ARSCLIST] SV: [ARSCLIST] Acetate tape discolours tape box

[Lars Gaustad <Lars.Gaustad@xxxxx>]

Dear Richard,
One reason for A-D strip reaction might be the fact that the softening chemical 
in PVC production are esters from phthalic acid that, as the decomposition of the 
PVC reaches a certain point, heat and light being the main catalysts,
Brakes the weak chemical bonds that holds the phthalathes in place 
 and we get an acidic reaction, non odourous as to the characteristics of phthalic acid.


lars gaustad 
senior preservation advisor
national library of norway
www.nb.no

> -----Opprinnelig melding-----
> Fra: Association for Recorded Sound Discussion List 
> [mailto:ARSCLIST@xxxxxxx] På vegne av Richard L. Hess
> Sendt: 19. oktober 2006 17:56
> Til: ARSCLIST@xxxxxxxxxxxxxxxx
> Emne: Re: [ARSCLIST] Acetate tape discolours tape box
> 
> 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. 
>