Adhesives for outdoor architectural historic azulejo conservation

Abstract

Historic ceramic tiles – azulejos – are an important part of the cultural heritage of Portugal. However, there are not many studies about the materials used in their conservation to direct the conservator’s choice. This work is, to our knowledge, the first comprehensive study on the adhesives used to bind fragments of architectural tiles. Attention is paid to the extreme conditions that may challenge the tiles when used outdoors. Three types of adhesives commonly used in tile conservation have been studied (acrylics, epoxies and cellulose nitrates) and several parameters related to their workability, efficacy, compatibility and ageing behaviour were analysed. Information was obtained about the adhesives characteristics and their suitability for the re-adhesion of fragmented azulejos in architectural outdoor environments.