[AV Media Matters] Deterioration of Acetate TAPES and FILM

[lists@richardhess.com]

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