Iron gall ink on parchment

Conservators who deal with parchment archives may be familiar with
this sort of problem, illustrated by Chris Clarkson in Fig. 41 of
his "Rediscovering Parchment: the nature of the Beast" article
(Paper Conservator, vol. 16). I have been asked to consolidate
flaking ink back onto parchment sheets from about 25 rolls of
archives, mostly dating from the mid- to late- 1500's, and extending
throughout the next century. The problem appears to be, as Chris
Clarkson and others say, one of humidity being present which then
allows the acidic ions in the ink to degrade the parts of skin that
letters are written onto, and this then has the effect of the
letter, and the weakened parchment fibres that were below it, coming
away either as a whole or in flakes. Many conservators advocate
piecemeal application of a consolidant with a fine brush between the
raised ink areas and substrate, but this isn't always feasible for
large areas and large numbers of sheets.

For such problems, research uncovered 2 printed sources:

    Michael Maggen.
    "Conservation of the Aleppo Codex"
    Restaurator, vol. 12, 1991

and

    Quandt, Abigail B.
    "The conservation of a 12th-century illuminated manuscript on
    vellum"
    The American Institute for Conservation of Historic and Artistic
    Works: preprints of papers presented at the Fourteenth Annual
    Meeting, Chicago, Illinois, 21-25 May 1986

Both authors advocate spraying a consolidant onto the sheet, that
has been put onto a vacuum table, and the consolidant both suggest
is parchment size. The suction pull of the table is applied to pull
the adhesive into the document, and so ensure consolidation at the
join between the ink and the substrate. Can anybody offer any advice
on carrying out such a treatment? I have been able to experiment on
other workshops' machines and had varying successes, and believe
that there is no other effective way of carrying out such work, if
it is to be done at all. Any advice gratefully received.

I have two  observations on this effect:

    1.  On the collection I am working on, the problem only occurs
        on documents dating from the late 16th Century onwards, and
        into the 17th. Earlier material, dating from the mid-13th
        century, does not display this characteristic. Is it the ink
        or parchment that altered, or both?

    2.  An interesting article on the nature of consolidation is at
        <URL:http://aic.stanford.edu/conspec/bpg/annual/v14/>
        (Julie Dennin Ream).

PS. Goldbeaters' skin now also available from

    William Cowley:
    <URL:http://www.williamcowley.co.uk>

as well as

    Henk de Groot:
    <URL:http://www.dedas.com/parchment>

Dominic Wall
Suffolk Record Office, Gatacre Rd. IPSWICH IP1 2LQ
United Kingdom
+44 1473 584547


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                  Conservation DistList Instance 14:46
               Distributed: Wednesday, February 21, 2001
                       Message Id: cdl-14-46-016
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