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Subject: Mass deacidification

Mass deacidification

From: Cor Knops <knops>
Date: Monday, April 6, 1998
There seems to be some confusion about the
"German-miracle-restoration-machine". I've seen several postings on
various lists about this subject, so I ordered some "real"
information from the people in Leipzig. I received 4 nice brochures
in which the whole process is described.

To begin with the myth that you put the book in at one end and take
it out (fully restored...) at the other end: this is nonsense!

The company ZFB (Zentrum fur Bucherhaltung) in Leipzig (which is on
it's own since January 1998; before that date is was a
semi-government institute) has automated a few things though. It's
founder and driving force, Dr. Wolfgang Wachter has been developing
paper-splitting  with a machine since 30 years or more. The result
is an automated splitting-machine in which you put (indeed) a leaf
in at one end and take it out on the other.

Let me please point out how they work (in general): The objects that
are offered to ZFB are first assessed. Depending on the damage
various treatments can be done:

Deacidification of books

    The ZFB uses the principles of the "Deutsche Bibliothek" in a
    mass-deacidification process. The books are first selected, then
    dried with moderate heat in vacuum. Then they are immersed in a
    non-aqueous deacidification-solution. pH-values are raised to
    7.5-9-5 and a buffer is built in the paper (1-2% MgCO3). Books
    with damaged covers can be repaired/restored in a more
    traditional way (mostly by hand).

Decontamination

    Paper damaged/covered by fungi or mold can be cleaned using a
    dry-cleaning method.

Wet-treatment

    Damaged paper is washed first in warm (de-mineralized) water.
    Paper containing wood-fibres are washed using boric-hydrides.
    Foxing and other types of stains are removed by
    oxidation-bleaching. Apart from the mass-deacidification process
    as described above they also use an aqueous calcium-magnesium
    bicarbonate solution. All these wet-treatments are performed in
    containers. The papers are captured between two layers of
    permeable substrate which are then submerged in the container.
    Weak papers can be resized using methyl-cellulose or
    carboxy-methylcellulose.

Leafcasting

    ZFB uses a leafcasting-machine which has a continuous flow of
    pulp. The objects move underneath the pulp-unit on a kind of
    conveyor-belt. The picture I've seen looks very much alike the
    machine which was designed by Laursen in Denmark (don't know if
    it's the same machine). Leaves that are treated have to be dried
    and further treated in the same way as the
    one-at-the-time-machine types.

Paper-splitting

    This is the huge machine everybody's talking about. Basically it
    splits the paper in two. Then a carrier-sheet can be glued
    between the two split-leaves therefore reinforcing it. This can
    be done fully automated or by hand (for valuable or difficult
    objects).

    The paper-splitting machine is used for certain kinds of
    degraded paper. It is only useful to deploy when the paper is
    internally weakened. When the paper is bound in a book, it has
    to be taken apart first (and re-constructed afterwards...). This
    limits the range of when a book can be put "in the machine". For
    a lot of material produced in the 19th century (e.g. bound
    magazines or newspapers) it is a very valuable process, but
    certainly not for all books or types of paper objects.

The ZFB has its own web-site <URL:http://www.zfb.com> but it is only
in German and not very extensive in technical details. You also
e-mail them for information (which I did) at info [at] zfb__com. The
person involved is Hans-Joachim Dose.

Just to make sure: I have no connection to this company. I just
wanted to clear some misunderstanding and I used only the
information that was given to me by ZFB. Hope it helps.....

Cor Knops
Knops Boekrestauratie
Restoration and Conservation of Books and Paper
Groenstraat 8
6151 CS Munstergeleen
Netherlands
+31 46 4200024
+31 46 511822
Fax: +31 46 4110180

                                  ***
                  Conservation DistList Instance 11:81
                  Distributed: Tuesday, April 7, 1998
                       Message Id: cdl-11-81-002
                                  ***
Received on Monday, 6 April, 1998

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