IRON GALL INK CORRODED AUTOGRAPHS OF THE 18TH AND 19TH CENTURIES
CONSERVATION OF MATERIAL CHARACTERISTICS VERSUS CONSERVATION
TREATMENTS
Irmhild Schäfer
Bayerische Staatsbibliothek München, Deutschland e-mail: irmhild.schaefer@bsb-muenchen.de
The conservation of so-called "exterior" characteristics of documents during conservation
procedures represents a challenging task. The wide range of materials and their different
degradation states are illustrated by means of autographs of the 18th and 19th centuries. Taking into
account the modern methods of conservation it is necessary to select optimised procedures for each
single case of damage.
There are. basically, aqueous and non-aqueous conservation treatments available for stabilisation of
documents. Besides the chemical and mechanical stabilisation of ink and paper, also other types of
information such as the iconic and material specifics of documents (e.g. surface of paper,
watermarks, color of ink, shellack and wafer seals, stamps) need to be preserved. The method used
here depends on the actual state of damage and also on the historical type of material.
1. Aqueous conservation treatments
By applying aqueous methods of mechanical strengthening in combination with aqueous methods
of chemical stabilisation all three central conservation aims can be achieved:
1. Removal or inactivation of ferrous ions.
2. Neutralisation or alkalinisation of sulphate ions.
3. Strengthening of the weakened paper.
We must be aware that aqueous treatments change the original composition of the inks. As a
consequence, future analysis of the inks would not provide any reliable information about the
historical recipes and the characteristic behaviour of the aged inks.
The following aqueous treatments are used:
- Conventional treatment:
An extremly thin tissue of Japanese fibres, known as "Gossamer tissue" (1,7 g/nr), is suitable for
mechanical strengthening of weakened paper in aqueous media. Depending on the degree of
damage and the type of historical material a stronger tissue up to 5 g/m: is required for effective
stabilisation of the paper. However, note that thicker application tissue may affect transparency.
- The tissue method and leafcasting machine:
A standard conservation method, applied at the Institute of Book and Manuscript Restoration of the
Bavarian State Library (IBR) Munich, involves the use of Japanese fibres for strengthening
weakened paper by forming a tissue in the leafcasting machine. The tissue can be applied partially
in order to keep free unaffected areas from fibres. - The tissue method and the use of a suction table:
Sensitive objects can be strengthened by a tissue produced in the leafcasting machine involving the
use of a suction table. The supporting tissue can be applied selectively to the weakened parts of the
paper.
2. Non-aqueous conservation treatments
In the case that aqueous treatments for the stabilisation of ink corroded papers are not suitable, we
rely on alternative, non-aqueous treatments. At present, non-aqueous conservation treatments do not
remove or inactivate transition metals. Therefore, the chemical stabilisation is restricted to the
neutralisation of acids by the application of carbonised magnesium ethylate. A tissue coated with
acrylate is used for the mechanical strengthening.
3. Concerns relating to the use of aqueous treatments
Aqueous treatments may raise problems, because they may effect the ink. Similarly, they may
interfere with other writing fluids, the stamping-ink, the wafer and shellack seals. Furthermore the
paper itself, its surface and dimensions as well as its watermarks need to be considered. In the case
of progressive damage there is the risk of worsening the degradation of the ink and the paper.
Aqueous treatments may also cause changes of the historical materials. Importantly, autographs of
the 18th and 19th centuries involve a wide range of writing materials. On one single document we
may find different kinds of ink used by the author and the contemporary readers, and notes on
envelopes in red chalk by the post office in the case of correspondence. Furthermore we may find
later additional notes of scientists as the first traces of research in direct neighbourhood to stamps of
the later owners of the documents. There are serious concerns that the different kinds of inks and
other writing fluids, pens, pencils or crayons are not stable against "bleeding" or other reactions
caused by water. Even worse, fixatives might be unstable in inappropriate chemical contexts.
The texts with microscopically fine ink endlines represent a valuable source of information about
the individual writing style of a historical personality. Even tiny remains of the drying sand, used by
the author immediately after writing, may provide significant insights into historical situations.
The seals, the fragile remains of wafers, the thin. Hat. baked adhesive disks made from starch as
well as the binders and the pigments deserve special attention. Their natural fragility could lead to
the complete breakage and loss. Therefore, wafers on a document may prevent the use of aqueous
treatments. Similarly, difficulties occur with shellack seals, which consist of shellack dissolved in
turpentine, colophonium and red pigments. Although they appear to be stable, under the
microscope they often reveal a lot of fine cracks. Moreover aqueous treatments require a thorough
drying process. Seals need to be carefully protected during this treatment. Nevertheless, centrifugal
folds, the "wrinkles", and the tensions around the seals might be the side-effects of aqueous
treatments.
4. Concerns relating to the use of non-aqueous treatments
Non-aqueous treatments need to be examined carefully regarding the long-term behaviour of
synthetic adhesives and possible changes of the optical as well as haptical impression of the
document.
5. Selection of objects
Also here, regarding the complexity of damaging factors and historical types of material on the one
hand, and the different conservation treatments on the other hand, we have to choose the best
method for each single object without affecting the iconic and material information. Each case of
damage requires its specific conservation treatment. Among undesirable side-effects arc not only
such apparently things like bleeding of the ink or increased mechanical degradation in the corroded
areas. Special attention deserve the more subtle characteristics of the historical materials in order to
minimize the risk of affecting them during the conservation treatments.