Conservation - Early methods 1890-1960

Birgit Reissland (1997)

 

"Die Ursache der herrschenden Unthätigkeit angesichts der unsere wissenschaftlichen Schätze bedrohenden Gefahren liegt ... zweifellos in der bis zu einem gewissen Grade nur allzuberechtigten Furcht vor der Gefahr und Verantwortlichkeit, welche fast mit jedem Rettungsversuche verbunden sind, zumal ja über die Güte der letzteren eben in den meisten Fällen nur eine Jahrzehnte umfassende Erfahrung entscheiden kann..." (O. Posse 1899: 8)

 

 

Focusing on historically used conservation practices is a tool for the conservator to assess damages caused by conservation measures used in the past. Therefore some of the historical methods are described in this chapter.

 

The "Internationale Konferenz zur Erhaltung uns Ausbesserung alter Handschriften" (International Conference for Preservation and Conservation Access of Antique Manuscripts), which took place in St. Gallen in 1898 (Posse 1899: 1 - 40) was the first conference to focus on problems relating to the preservation of ink-corroded cultural heritage. The participants of this conference were primarily directors of European libraries and archives. In addition to outlining the symptoms of ink corrosion, they also discussed preventive and active conservation issues as well as measures which need to be taken.

 

Impregnation using "Zapon" (method used by the end of 19 c. - beginning of 20 c.)

This process was developed by Dr. Schill, a medical officer from Dresden, to enable personnel in the armed forces to read maps outside - even in the rain (Posse 1899: 15). Posse introduced this process to the participants of the St. Gallens conference. During a subsequent conference for German archivists (Dresden, 1899), he gave a practical demonstration of the process. Zapon, a cellulose nitrate (possibly with camphor added as a plasticizer) was dissolved in acetone and a colorless liquid was formed. Its viscosity was adjusted by addition of solvent. The solution was applied to the degraded papers by immersion, spray or by brush. The impregnated papers were dried on grids. Already 1909 the "Königliches Materialprüfungsamt Berlin" warned that papers treated in this manner are highly flammable. Furthermore it was stated, that decomposition of Zapon affects the paper support, causing the progressive yellowing noticed in those days. Substitution of Zapon by a less flammable cellulose acetate ("Cellit") was suggested.

Infills using the Gelatine / Formol procedure (method used by the end of 19c. - beginning of 20 c.)

Franz Ehrle, initiator of the St. Gallen conference, suggested the use of pure, salt-free gelatine (used for photography) to replace losses in parchment caused by the degradative effect of iron gall inks. First, a support paper was adhered to the backside of the artifact. The losses were filled with thin layers of gelatine, until the thickness of the artifact was reached. This procedure was quite time-consuming (Posse 1899: 31). Alum or "Formol" (40% solution of formaldehyde in water) was added to prevent mould growth. Because gelatine tended to be brittle due to the use of Formol, addition of glycerine was proposed (Posse 1899: 33). The necessity to modify the treatment indicated disadvantages associated with the method. In addition, gelatine-infills remained sensitive to changes in humidity, so long-term contact with adjacent leaves might cause adherence of the pages.

 

Ammonia collodion process (method used by the end of 19 c. - beginning of 20 c.)

For the first time, this method proposed to neutralize free acid using ammonia vapors prior to mechanical stabilisation of ink-corroded artifacts. After neutralisation, papers were mechanically stabilized using collodion (cellulose nitrate1). The disadvantage of this method was strong shrinkage of the collodion impregnated papers. As a subsequent point of critique it was mentioned, that the collodion does not penetrate the artifact but forms a thin skin on its surface (Posse, 1899:33). Addition of castor oil as a solvent was also mentioned. Today the papers, treated by the ammonium collodion process, probably appear comparable to the Zapon-impregnated papers (Zapon, as well as collodion, is a cellulose nitrate). The artifacts are highly flammable. A neutralisation using ammonia has no long-term stabilizing effect (Wächter 1987: 23).

 

Lining / lamination using transparent papers (method used ca. 1940)

In 1964 Hans Heiland mentions that strongly ink-corroded manuscripts, used for genealogy studies during the Third Reich, were embedded between transparent papers (Pergamin-papers) at a central office in Berlin. After 30 years severe yellowing of the artifacts was observed (Heiland 1964: 216). The glue that was used has not been identified, although it is thought to be starch.

 

Stabilisation using chiffon-silk (method used between ca. 1920 - 1960 ?)

Hugo Ibscher studied the use of chiffon-silk for lining ink-corroded artifacts at the studio of Franz Ehrle in Rome and sheared his knowledge all over Europe. The results of his work can be accessed in many libraries in Europe (for instance at the Staatsbibliothek Preußischer Kulturbesitz Berlin). Objects treated in this manner may be detected by pieces of thread sticking out of the edges.

One of the very few notes concerning treatment of silked artifacts was found in an article by H. Heiland in 1964. He treated a manuscript damaged by mould, that could not be treated by aqueous methods (because its inks were not water stable), in the following way: he sprayed 90% alcohol (not specified) or a solution of "Formalin" (40 % solution of Formaldehyde in water) to inactivate the mould. Lining the page using chiffon-silk as a support and a "preserving starch" followed. Unfortunately, no more detailed information is available.
Objects treated in this way are seriously damaged, because chiffon-silk, paper, and media are in intimate contact and can not be removed without the danger of loss of substance (Bartelt 1981: 165 - 168 and 1997). Additionally, due to the use of aqueous adhesives (e.g. wheat and rice starch paste) damage was spread over the whole page. This is because soluble iron (II) ions migrated and adhered preferentially to the threads of the chiffon-silk material.

Silvia Rodgers Albro and Holly Krueger (Library of Congress) removed chiffon-silkings applied with wheat starch paste using enzymes (amylases) in a water/ethanol solution (Rodgers and Krueger 1997). Recent investigation by Dirk Schönbohm allowed the removal of the silk from water-sensitive, ink-corroded papers by using partly non-aqueous techniques (partly non-aqueous amylase-gels with added methoxy-ethanol)(Schönbohm 1998).

 

Lamination using acetate or PVC-films (method used between 1950 - 1960?)

Nils Gärting proposed embedding of damaged papers in acetate- or PVC-films in exceptional cases only and emphasized the irreversibility of such a procedure (Gärting 1963: 111). Objects treated in this manner are today strongly yellowed and damaged by acetic- or hydrochloric acid emitted by the film material or migration of its external plasticizers.

At the end of the 80's, successful de-lamination of parchment manuscripts, dated from the 8th century, was achieved in Vienna ("Karolingisches Evangeliar", Wächter 1987: 34 - 38) and Brussels ("Codex Eyckensis", Wouters et al. 1990: 495 - 499, 1992: 67 - 77). PVC-film material (brand name: "Mipofolie" 2) was removed by immersion of the artifact in ethanol:amylacetate 4:1, sometimes adding butyl acetate (Vienna), or the film material was mechanically removed after pre-wetting with ethanol:amylacetate 4:1 (Brussels).

 

Footnotes

In the article incorrectly named "Schießbaumwolle", a cellulose dinitrate. back to text producer: "Alfred Schwarz GMbH & Co", Overath-Untereschenbach, Germany (Wouters et al. 1990: 496). back to text