Conservation of the prayer book of Mary of Guelders


Two years ago, the conservation studio at the Staatsbibliothek zu Berlin started to devise a plan for conserving the manuscript of the prayer book made in 1415 for Mary of Guelders (1380–after 1429). The 500-hundred-page manuscript is one of the most precious items in the holdings of the Staatsbibliothek zu Berlin. At the Staatliche Museen’s Rathgen-Forschungslabor (Rathgen Research Laboratory) the prayer book was thoroughly examined and the conservation programme worked out.

In and around Nijmegen, where the manuscript originated, there is still great academic, cultural and public interest in the prayer book and in Mary of Guelders herself.  Born in France, Mary became Duchess of Guelders and Julich on her marriage at the age of 25. The prayer book made for her in the duchy contains several devotional texts written especially for her. More than 600 years old and containing 92 miniatures and numerous historiated initials and illuminated borders, the book is an outstanding example of early 15th-century Netherlandish manuscript painting.

Exhibition from 13 October 2018 in Nijmegen: I, Mary of Guelders. The Duchess and Her Famous Prayer Book

In the Department of Medieval and Early Modern Netherlandish Literature at the Radboud Universität Nijmegen, specialists from several disciplines, led by Johan Oosterman, are researching the life of Mary of Guelders and, in particular, her prayer book. The results of their research will be presented to the public in an exhibition, opening on 13 October 2018 at the Museum Het Valkhof in Nijmegen, entitled I, Mary of Guelders. The Duchess and Her Famous Prayer Book. The exhibition will be accompanied by a catalogue and an academic conference. On show, as well as the prayer book from the Staatsbibliothek zu Berlin, will be paintings, fabrics, jewellery, sculptures, stained glass and saint figures, many on loan from foreign collections.

In the exhibition there will be forty pages from the prayer book of Mary of Guelders on display, something which is only possible because the individual leaves have been permanently removed from their original binding. After conservation, they will be bound in layers and stored at 18 degrees Celsius in specially-made cases in the vaults of the Staatsbibliothek zu Berlin. To restore the manuscript to its binding would be to reproduce the conditions which caused the damage in the first place; for example, the parchment being rigidly fixed to the spine and the pages flexing when turned.

Damage analysis and conservation plan

Since the 1990s, no use of the prayer book has been possible; there were losses in the paint layers, and in many places the parchment itself was cracked and even broken. Radboud University’s plan to mark the 600th anniversary of the manuscript with an intensive new research project focussed attention on the long-needed conservation of this object.

In 2016, the Staatsbibliothek zu Berlin and the Rathgen-Forschungslabor – both part of the umbrella organisation Stiftung Preussischer Kulturbesitz – began an intensive collaboration, aimed, firstly, at analysing the damage to the individual leaves, and then at working out a conservation plan. Both institutions were financed by the Ernst von Siemens Art Foundation. The questions investigated by the Rathgen-Forschungslabor included why the parchment was cracking at certain places, whether the damage was getting worse, and, if so, what was causing it. Technical art-historical questions were also investigated; for example, how many painters were involved in the illumination and what pigments did they use?

The conservation programme which has been devised aims to stabilise the prayer book and prevent any further damage. Nothing is actually being restored. To ensure that the coloured pigments and gold leaf adhered to the parchment support and did not flake off, a microscope with 48-fold magnification has had to be specially acquired and installed in the laboratory. It was bought with funds that Radboud University had raised for the conservation of the prayer book.

The texts themselves are personal prayers, some of them specially written for Mary, Duchess of Guelders. However, prayers from other European traditions are also preserved, often adapted for the book’s owner. All the texts are evidence of the highly developed literary and devotional culture of the time.  

Further information about the prayer book can be found at

A collaboration between the Staatsbibliothek zu Berlin, the Rathgen-Forschungslabor, Radboud University and the Museum Het Valkhof, Nijmegen.