Deterioration of Acetate TAPES and FILM

["Richard L. Hess" <lists@xxxxxxxxxxxxxxx>]

Hi, ARSC and AV-Media Matters folk.

Sorry for the cross-post, I think there is a good percentage of 
non-overlapping membership.

As many of you know, Jim Wheeler and I transferred useful content from 51 
reels of tape dating from the late 1940s.  This cache belonged to Bill 
Palmer who, for some time in the early days, was Jack Mullin's partner in 
getting professional tape recording off the ground in the USA. These tapes 
are all 1/4-inch (or 6.5mm) wide and are both acetate- and PVC-based 
formulations. The acetate-based tapes are coated, the PVC-based tapes are 
homogeneous (that is to say that the magnetic particles are embedded in the 
film, not coated on it).

We've had some great advice from film preservationists to test for "vinegar 
syndrome" using the Acid-Detection (A-D) strips from the Image Permanence 
Institute of the Rochester Institute of Technology. We are now thoroughly 
confused. While the A-D strips are showing some acidity in the boxes, they 
are showing more acidity in the acetate tapes (1.0-2.0, partially depending 
on wind density and other factors), but even a measurable amount (1.0) on 
the PVC tapes. The latest test put the tapes in ZipLoc freezer bags for 
about 18 hours with the strips. An empty bag showed a good clean "0" and a 
strip left out in my home office showed after a week of LA air still very 
close to "0!"

What I don't understand is that I've been seeing posts concerning severe 
degradation of magnetic films (both 16mm and 35mm) while neither Jim nor I 
have any significant reports of the same type of degradation from audio tapes.

We are wondering if there is any significant degradation of acetate audio 
tapes from "vinegar syndrome" in any archive? And, if so, what are the 
storage conditions both physical and climatic?

If there isn't any significant degradation of tapes,  but there is of 
films, we're trying to understand the differences (we're especially 
interested in the state of 1/2-inch and wider acetate-based audio tapes to 
understand the relationship of media thickness to the problem) and what the 
causes of the differences might be. This is partially to avoid creating the 
same conditions that have accelerated this degradation for film, and 
hopefully to understand what the audio community has done--probably by dumb 
luck--that can be transferred to the film community to arrest/prevent 
further "vinegar syndrome" deterioration in the magnetic films.

The major difference that we see relates to storage practice. Audio tapes 
are typically stored inside cardboard boxes of moderate acidity. Many turn 
brown (or the inserts turn browner) with age and show all the telltale 
signs of acidic paper degradation). We are aware that archival boxes are 
(or at least were) available. It seems that magnetic films are typically 
stored in sealed metal cans--typically plated steel.

Any information about degrading acetate audio tape and "vinegar syndrome" 
would be greatly appreciated.

Cheers,

Richard