European Journal of Science and Theology, April 2015, Vol.11, No.2, 129-140 _______________________________________________________________________ ETHICAL AND TECHNICAL CONCERNS DURING THE CONSERVATION PROCESS OF A RELIGIOUS BOOK THE BOOK OF HOURS FROM THE LIBRARY OF PALÁCIO NACIONAL DE MAFRA Rita Araújo 1,* , Conceição Casanova 1, 2 , Maria João Melo 1, 3 and Ana Lemos 4 1 Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia, Departamento de Conservação e Restauro, 2829-516, Monte da Caparica, Portugal 2 IICT (Instituto de Investigação Científica Tropical), R. Junqueira 86-1º, 1300-344 Lisbon, Portugal 3 Universidade Nova de Lisboa, Requimte, Faculdade de Ciências e Tecnologia, 2829-516, Monte de Caparica, Portugal. 4 Universidade Nova de Lisboa, Faculdade de Ciências Sociais e Humanas, Instituto de Estudos Medievais, Avenida de Berna 26-C,1069-061 Lisbon, Portugal (Received 15 January 2015, revised 27 January 2015) Abstract This paper discusses the ethical approach and decision making for the conservation of a French book of hours (cofre no.24), currently stored in the 18 th century library of Palácio Nacional de Mafra (PNM), in Lisbon, Portugal. This book of hours, named cofre no.24, has the manuscript’s original text block dated from ca. 1420 and three folios were added later, in the second half of the 15 th century. The conservation decision was taken based on the study and full comprehension of the techniques and materials present in the book and bearing in mind the significance and the role of this symbolic book, throughout its life. The main aspects of diagnosis of the condition of the book are presented and the conservation treatment briefly described. The colours analysed reveal the artist’s original trace and no other alteration, reinforcing the proposed minimal intervention for the text block. As opposed, the binding of the late 18 th /early 19 th centuries was in very poor condition, requiring the rebinding of the whole book. Treatment decisions are raised and discussed, namely the choice of maintaining the binding found versus recovering old bookbinding features, as the main theme of an ongoing research. Keywords: book of hours, bookbinding, silver leaf, pigment identification * E-mail: araujo.ritaa@gmail.com, tel.: (+351) 962880650