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International audience; This article presents the case of blue paper in a sample book that once belonged to Victor Poterlet, a French wallpaper designer operating in Paris in the 19th century. Prussian blue is the main colourant used to dye the paper. The condition of the paper is very poor, probably due to the presence of free iron ions. However the paper could not be replaced or chemically treated because it supports 954 samples, which could not be dismantled due to time considerations. Moreover the paper is indubitably of high aesthetic value and an inherent part of the original. This study was carried out in order to optimise the reinforcement of the blue paper through local treatments, such as resizing and/or lining. Tests were also undertaken to evaluate improvements in mechanical properties induced by these treatments. In addition it was found necessary to estimate any colour changes that could result from the application of an adhesive to a deep blue paper. Several adhesives were evaluated: Tylose, Klucel, gelatine, starch, Funori, Lascaux 498HV and Lascaux 360HV. The best results were obtained with Tylose. Finally, the book was consolidated with linings that were applied by reactivating the adhesive. This method offered a satisfactorily compromise between the best reinforcement and the least colour change

International audience; The experimentation with new ideas and techniques in contem-p o r a ry art can lead to substantial conservation issues in the near f u t u re, especially when the artist tries to fuse two incompatible materials into one object. This is the case with the 'Print of thre e rusted iron plates', created by the French contemporary art i s t B e rn a rd Pagès and now in the Museum of Modern Art, Saint Etienne, France. Although contemporary, this print alre a d y shows serious damage caused by the presence of iron in the p a p e r. It was so brittle that it could no longer be handled nor be displayed. This type of artefact raises fundamental questions for paper conservators: its degradation is extremely rapid and inherent to the combination of its constituents (iron compounds and paper) that obviously cannot be separated. It also necessitates investigation into the possibilities of using available chemical t reatments in order to limit the degradation mechanisms while keeping in mind that the visual appearance should re m a i n unchanged. Historical Background 'Print of three rusted iron plates' is one of the series of prints and drawings created in the 1970's by Bern a rd Pagès while he was working under the influence of the avant-garde, Support s / S u r-faces' gro u p (Abadie 1999; Exhibition catalogue, 19 91, 2002). A s an established sculptor, he worked with raw materials and tried to escape from personal expression by using printing methods that place the object in the centre of the creation process. These methods consisted of etching a hydrochloric acid solution on steel plates in order to encourage the formation of rust. These plates were then pressed on the paper, producing prints of ru s t. F i n a l l y, the artwork was completed with graphite pencil and black ink lines that emphasised the borders of the central plate (Fig 1). Description of the Arte f a c t F rom a chemical point of view, the work is in fact a thick ru s t layer embedded in a contemporary wove paper, commonly known as 'Vélin d'Arches' and manufactured by C a n s o n. One edge features a watermark, 'Dessin-Ja-Arches-France'. The paper is now very brittle and fractured in many places. Two pieces are missing. The sharpness of the edges shows that the frac-t u res are due to loss of paper flexibility. Raking light observ a t i o n revealed undulations. Unprinted areas are light brown and hig-' E m p reinte de trois plaques de fer rouillées' (Print of three ru s t e d i ron plates) was produced in the 1970's by the artist Bern a rd Pagès according to a specific protocol: steel plates were etched with a hydrochloric acid solution then pressed onto paper to create ru s t prints. Although contemporary, this work of art already shows serious damage caused by the presence of iron in the paper. Various conservation treatment possibilities were explored to pre-s e rve the artefact. Replicas were made and used to evaluate the dif-f e rent options. The application of the calcium phytate tre a t m e n t , initially developed for iron gall ink corroded manuscripts, was investigated and it turned out to be efficient in preventing degradation of the replicas. The addition of alcohol to the treatment solutions was also considered, but was eventually not tested, as it tends to decrease the treatment effectiveness. It was finally decided to use pure aqueous solutions and to float the artefact during the treatment. The treatment was undertaken twice without inducing any visual changes to the artefact. Some free iron (II) still remained in the paper after treatment but to a much lesser extent than before treatment. This suggests that the intervention was at least partially effective. As the artefact re q u i red consolidation and lining, the capabilities of several commonly used adhesives that change paper sensitivity to water were evaluated and compare d. Gelatine was finally chosen for consolidation as it renders the paper the most hydrophobic compared with starch, hydro x y p ro-pylcellulose or methylcellulose. After lining, the artefact was mounted in a frame specially designed for safe display.

International audience; This tutorial review intends to show, through demonstrative examples chosen from the recent literature, how surface characterisation conducted by modern investigation methods leads to very rich information on a cultural heritage artefact's history, fabrication techniques and conservation state. Application of surface science to conservation science is of great help for the definition of a conservation and restoration policy for museum and archaeological objects. A brief description of the investigation methods is given, together with relevant references for more detailed information.