Damaged microfilm set

John Haar wrote

    >... we've discovered a problem with one of our microfilm sets and
    >want to pass along the information so others who own the set can
    >check on the condition of their copies.  Staff discovered that the
    >set, The Timothy Pickering Papers (69 reels), was emitting a
    >substance that had damaged both the cardboard reel containers and
    >the metal cabinet in which they were stored.

I'm sure that what you must have is a set of the old Kalvar vesicular
microfilm.  Many institutions had their metal cabinets damaged by this
film, which emits hydrogen chloride gas (or hydrochloric acid).  The
acid also destroys the cardboard boxes in which the film is kept,
turning them into fragile shells which disintegrate when you touch them.
We had some of this film, but had it replaced with silver halide
microfilm.  As far as I know the corrosive gas did not affect the
non-vesicular film around it, but probably that film is now about to
suffer from "vinegar syndrome," so you can't win!

Your film wasn't a "faulty" film, in terms of being an unusual example
of its kind, but rather that it was film of a particular formulation,
which appeared in the late sixties I think, where the film began to give
off hydrogen chloride gas--something which the manufacturers obviously
didn't expect. You can find articles in various library journals about
this.

In the standard ANSI PH1.67, American National Standard for Photography
(Film)--Processed Vesicular Film--Specifications for Stability, in
Appendix F, Corrosiveness, you find this statement:

    "There have been some commercial vesicular films that have released
    hydrogen chloride during storage.  This behavior has not had any
    known detrimental effect on the stability of the film itself.
    However, it did have a very corrosive effect on the film enclosure
    materials, particularly on metal film cans and storage cabinets."

Because we couldn't afford metal cabinets for all of our films, we were
lucky in that the only damage we suffered was minor signs of corrosion
on our metal stack shelves.  Most of the damage was to the boxes in
which the film was stored. We ran through two sets of these before the
micropublisher agreed that it was the film which was causing the
problems, not the boxes.  We insisted on having all the film replaced
with silver halide film, because we were leery of any vesicular film at
that point.  Current vesicular films, however, do not have this problem
because they have a completely different formulation from the old Kalvar
film.

Suzanne Dodson
Facilities and Preservation Manager
University of British Columbia

                                  ***
                  Conservation DistList Instance 7:58
                Distributed: Thursday, February 10, 1994
                        Message Id: cdl-7-58-005
                                  ***