Please cite this article in press as: E. Bourguignon, et al., Calcium alkoxides as alternative consolidants for wall paintings: Evaluation of their performance in laboratory and on site, on model and original samples, in comparison to conventional products, Journal of Cultural Heritage (2017), http://dx.doi.org/10.1016/j.culher.2017.07.008 ARTICLE IN PRESS G Model CULHER-3256; No. of Pages 13 Journal of Cultural Heritage xxx (2017) xxx–xxx Available online at ScienceDirect www.sciencedirect.com Original article Calcium alkoxides as alternative consolidants for wall paintings: Evaluation of their performance in laboratory and on site, on model and original samples, in comparison to conventional products Elsa Bourguignon a , Patrizia Tomasin b,∗ , Vincent Detalle a , Jean-Marc Vallet c , Martin Labouré d , Iulian Olteanu e , Monica Favaro b , Matteo Andrea Chiurato b,f , Adriana Bernardi g , Francesca Becherini g a LRMH, 77420 Champs-sur-Marne, France b CNR-ICMATE (previously CNR-IENI), Padova, Italy c CICRP, 13003 Marseille, France d Prestim Groupe, 67560 Rosheim, France e SC DUCT SRL, Bucuresti, Romania f Department of Life Science and Biotechnology (SVeB), University of Ferrara, Ferrara, Italy g CNR-ISAC, Padova, Italy a r t i c l e i n f o Article history: Received 3 February 2017 Accepted 25 July 2017 Available online xxx Keywords: Calcium alkoxides Wall paintings Consolidation treatment Consolidants’ performance evaluation Cultural heritage conservation Impact testing device a b s t r a c t In the field of cultural heritage conservation, wall paintings treatment is a particularly complex issue, which requires a suitable choice of materials. In this paper, two innovative calcium alkoxides, calcium tetrahydrofurfuryl oxide [Ca(OTHF) 2 ] and calcium ethoxide [Ca(OEt) 2 ], are proposed as new products for the consolidation of wall paintings. They were developed during the NANOMATCH European project and their efficacy, compatibility with the substrate and durability were evaluated in comparison with commercial products on both model and real samples. Model samples were exposed in four different sites around Europe to investigate the treatments’ behaviour under different climatic conditions. The main research results are reported here: alkoxides showed to be a good option for wall paintings’ consolidation especially in presence of certain binders and pigments. Finally, an impact testing device was used for the first time for the evaluation of the consolidants’ efficacy and thus proposed as a reliable methodology for their performance assessment. © 2017 Elsevier Masson SAS. All rights reserved. 1. Introduction and research aim Wall paintings are one of the most ancient forms of art. Wall paintings decorate architectural surfaces, and unlike other types of paintings, they cannot be isolated from the architectural struc- ture they adorn and its environment [1,2]. A wall painting is a multi-layered system applied to an architectural support. A common European historic wall painting is often composed of three layers: a coarse mortar ground layer (arriccio), applied to the support, then a fine mortar finishing layer (intonaco) onto which is applied the painting layer. Several painting techniques exist; in the fresco (affresco) technique, the pigments, dispersed in ∗ Corresponding author. E-mail address: patrizia.tomasin@cnr.it (P. Tomasin). (lime) water, are applied on a fresh and still damp lime mortar (intonaco). Pigments can also be applied on a dry and set intonaco (a secco technique): in that case they require to be mixed with an organic binder, such as yolk/egg, casein/milk, glue, natural gums, oils, etc. The conservation of wall paintings is thus a complex issue due to their layered nature and their position as an integral part of an architectural structure. Many factors can play a role in their deteri- oration: lack of stability of the architectural structure itself, water, salts, light, and so forth. Multiple agents of deterioration often act in synergy, however the presence of water is often the key deterio- ration factor as it enables the migration of salts and determines the location of their re-crystallization, it acts as solution for polluting acids, it is a requirement for frost damage. Moreover, most biolog- ical attack and some chemical reactions (especially in pigments) do not take place in the absence of water [1]. Various deterioration http://dx.doi.org/10.1016/j.culher.2017.07.008 1296-2074/© 2017 Elsevier Masson SAS. All rights reserved.