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Subject: Leather bloom

Leather bloom

From: Jeffrey Kaimowitz <jeffrey.kaimowitz>
Date: Tuesday, March 22, 1994
I am posting this inquiry regarding spue from Professor Henry DePhillips
and his Student Assistant Michele Mader:

    Question: Does anyone have information or ideas on how the methods and
    materials used for preparing leather for binding books from the 18th
    century through the 20th centuries as well as leather treatments used
    today to preserve such books could lead to spue formation?

    We are analyzing spue formation with the aim of eradicating it.  If
    anyone is willing to share samples with us, we will do the analyses here
    in our lab.  Please contact us directly at the addresses listed below.

    Dr. Henry A. DePhillip, Jr.
    Vernon K. Kriebel Professor of Chemistry
    Trinity College
    Hartford, CT 06106
    Henry.DePhillips [at] mail__trincoll__edu

    **** Moderator's comments: I'm not certain what is meant, in this
    context, by "spue" but I suspect Dr. DePhillips is referring to what
    we usually call bloom (hence my assignment of the Subject heading
    above). "Bloom" is defined in Roberts and Etherington thus:

        1. A deposit of ellagic acid formed in and on leathers tanned
        with vegetable tannins of the pyrogallol class, probably as a
        result of the action of enzymes native to the original source,
        i.e., bark, acorns, etc. Although bloom affects the physical
        properties of leather in that it increases weight yield,
        firmness, and water resistance, it is deposited in insoluble
        form and is not chemically combined with the fibers of the
        leather. Its presence at times gives an unsightly appearance to
        the leather. 2. A misty surface appearance in an illustration,
        caused by an excess of acid or too much drier in the ink. 3. The
        dulling film that sometimes appears on varnish and glossy paint
        films, particularly in industrial atmospheres. It usually
        consists of minute crystals of ammonium sulfate produced by the
        reaction between sulfur dioxide, ammonia, and oxygen in
        condensed moisture on the film. Bloom can appear on a freshly
        lacquered surface when rapid evaporation of the solvents causes
        the temperature of the surface to fall below the dew point.
        Moisture is deposited on the film, causing a limited
        precipitation of cellulose nitrate and giving the film a
        permanent cloudy appearance.

Jeffrey H. Kaimowitz
Curator, Watkinson Library
Trinity College
Hartford, CT 06106

                  Conservation DistList Instance 7:66
                 Distributed: Wednesday, March 23, 1994
                        Message Id: cdl-7-66-005
Received on Tuesday, 22 March, 1994

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