Storing photographic materials

Deborah Howe <d-howe [at] nwu__edu> writes

>In response to the discussion on non-buffered vs. buffered
>interleaving tissue for use in photo albums, we did some testing
>here at Northwestern.  In accordance to accepted practice we
>purchased non-buffered interleaving tissue about 5 years ago to use
>in photo albums....
>...
>Yesterday I went to retrieve the album and pH tested the tissue.
>The result was a reading of 3.2-3-5.  We still have the original
>roll of tissue and the reading on that came out to 6.0 pH.  I also
>took readings of the support pages both from one that didn't have a
>tissue facing it and the other that did, both readings came out at
>3.7 pH.  My question is what would be recommended at this point:
>remove the tissue and replace with buffered tissue or just remove
>and leave well enough alone?

Generally I have tended to avoid interleaving albums because of
problems during use (researchers mess it up, leave it out, or worse,
get it crinkled) or problems with putting too much stress on the
binding. Barring high use rates or binding strain, interleaving is
most appropriate under certain circumstances--

    1.  abrasion of photos which face each other with edges of one
        cutting into the surface of another due to pressure in
        storage (or through scraping across during heavy use when
        pages are turned);

    2.  fading or staining clearly associated with contact with:

    a.  photo reactive album leaf paper, adhesive residues, tapes or
        inks etc.

    b.  poorly processed photos with fixer stains, etc.

    c.  certain reactive photo processes eg platinum or platinum
        toned prints which might adversely affect other processes.

    3.  blocking of pages/photos for some reason (usually adhesives
        or high humidity)

Certainly poor quality paper in album pages (and mounting adhesives)
can contribute to fading, silvering, or image discoloration.  But
these effects are also highly dependent on elevated relative
humidity and temperature.  According to Reilly et al (Acetate
Storage Guide), very little image oxidation by reaction with
contaminants will occur if the RH is below 40-50%. At these low
RH's, the emulsion is a good barrier to contaminants, there just
isn't enough moisture for many of these reactions to go, or for the
oxidized silver to migrate to the surface and redeposit as mirror.

Therefore, if I see image deterioration, I usually suspect that it
occurred when the album was stored in an uncontrolled climate. this
is usually the case before an album is acquired by a repository. I'm
always surprised at the panic about black or colored paper
albums--even when there's little evidence of deterioration, or only
minor deterioration that is probably the result of poor storage
conditions. Many an album has been unnecessarily disassembled or had
it's spine broken by excessive interleaving only because it pages
were the wrong color and deemed suspect.

If the image deterioration is severe and linked to the album
materials, pages/photos are blocking, or if album pages are
embrittled and likely to break during use, I would consider various
options.  These might include interleaving, researcher surrogates
(photocopies, etc), and as a last resort, album treatment (such as
disassembly and sleeving or complete removal of photos).

Not knowing your exact situation, I can't say whether or not
interleaving is really required.  I see no need to keep paper in
there that is more acidic now than the album itself. Since you have
the unbuffered paper on hand, you could use some of that if you feel
the situation calls for interleaving, based on the parameters
discussed above. The current interleaving paper has absorbed acidity
from the album, which is of benefit as long as it can be replaced
periodically when it becomes highly acidic.  Buffered paper would
require less frequent replacement on that account.

Sarah Wagner
Photograph Conservator


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                  Conservation DistList Instance 13:45
                 Distributed: Friday, February 25, 2000
                       Message Id: cdl-13-45-002
                                  ***