They are huge, unique and of inestimable value: the eight Naumburg missals created in the early 16th century. Until 1874, they used to be the core of the daily liturgy in Naumburg Cathedral. With a height of up to 84 cm, a width of 66 cm and a thickness of over 16 cm, they are among the largest medieval books in the world.
But the centuries of use of the volumes have left their mark. Above all mechanical influences have led to cracks and creases in the parchment and to numerous bumps. Soiling and ink corrosion must be treated for restoration. Therefore - thanks to the help of the State of Saxony-Anhalt and the Ernst von Siemens Foundation - three books were comprehensively restored at the Cologne University of Technology. They are now back in the archives of Naumburg Cathedral and will be exhibited in a separate room in the future.
The wooden bindings of the Naumburg missals are covered with pigskin, into which extensive decorations have been embossed by means of a blind pressing typical of the time.
In addition to their sheer size, the Naumburg missals are distinguished by their particularly splendid book decoration. Especially text and song sections on the most important festivals, the so-called high festivals, are decorated with magnificent ornamental pages. In addition to extensive miniatures and filigree initials, numerous motifs from the animal, plant and mythological world as well as from the everyday life of the people enliven the margins decorated with acanthus tendrils. The elaborate decoration is one of the highlights of late medieval book illumination.
The thick wooden cover bindings of the missals have partly deformed dramatically due to moisture infiltration, thus endangering the valuable parchment blocks of the books. Although the volumes impress every observer with their size, the book covers are still too small for the parchment blocks in between, which they are supposed to protect. The deformations lead to the fact that the volumes can no longer be closed. The resulting free pressure not only causes the spines of the books to break open, but also causes the parchment sheets to swell, which in turn leads to the loss of writing and painting.
Restoring the original stability by straightening the bindings is one of the most important goals of the restoration and indispensable for the future preservation of the books.
The parchment of the various volumes was stabilized, the ink corrosion strengthened and the shifted book covers, as a main task, were straightened. This is the most complex work due to the size of the volumes and because all the metal closing decorations and humps are still there. The straightening was done without taking the volumes apart. For this purpose the wooden covers were treated with a technique known as Sverzatura. The books were then fixed with straps, so that there is a permanent pressure on the parchment sheets which counteracts the renewed deformation.
The restoration of the choir books was made possible by the generous support of the state of Saxony-Anhalt, which provided 40,000 € for the project, and by the Ernst von Siemens Kunststiftung, which contributed 15,000 €. Martin Hoernes, Secretary General of the Ernst von Siemens Kunststiftung, explains: "The restoration of these valuable parchment manuscripts was a considerable challenge in view of the huge formats. The Ernst von Siemens Kunststiftung is particularly concerned to support the long-term preservation and conservation of such threatened unique artefacts".