Soil profiles

I am a librarian/aspiring archivist working for special collections
at Humboldt State University on a grant-funded project processing a
large 1960s-2000s era manuscript collection of a former professor
there.  In this collection are numerous soil profiles, in which soil
mixed with spit has been mounted on special absorbent paper and
fixed with a fixative.  These profiles are annotated and contain all
kinds of textual information in addition to the soil, and represent
an important aspect of the professor's approach to ecology.  From
that point of view I would like to keep them or a sampling of them
with the collection, but I am concerned about how these materials
might deteriorate over time or physically affect the surrounding
contents of the collection.  I would like to make an informed
decision with my supervisors by having greater knowledge about the
potential consequences of keeping this material to weigh against the
intellectual benefits of keeping this material.  I do know the
specifics about the materials used to create these soil
"spit-o-grams":

    The paper used is from the Holland-based company Vel Prima
    Beschrijfboar Papier and was chosen because it was "thin,
    absorbent and strong"

    Approximately 3 grams of soil for each horizon (usually three or
    four horizons per profile) was mixed with a small amount of
    "sputum" to form a paste.  This paste for each horizon was
    rubbed firmly over a 2-3" square of the paper.  The goal was to
    being "to impregnate the soil color into the pores of the
    paper".  When done correctly, this made the opposite side of the
    paper damp.

    Excess soil particles were then brushed off so that only the
    thinnest layer of soil was left on the paper.

    The "spit-o-gram" was then sandwiched between two non-absorbent
    papers, and these three sheets were "flattened between absorbent
    surfaces in the laboratory  until dry"

    Once dried, a fixative was applied.  Grumbacher number 546 in a
    spray can was used (a clear, non-glossy artist's fixative).

    Finally, the entire sheet was mounted to a heavier paper such as
    botany paper using rubber cement. On the botany or other paper
    backing, additional information was written to provide the
    textual information component of the soil profile.

Any guidance or information folks have to provide would be very
helpful in determining how to best treat these items and their
relationship to the collection as a whole.  So far, I have noticed
that the profiles are pretty stable in that soil particles do not
seem to come off of them easily.

Adrienne Harling, M.L.I.S.
Archives Cataloger
Humboldt State University Library


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