Injection grouting for delaminated wall paintings : approach, design, challenges

Abstract

A decorative architectural surface is any decoration for which the support is the structure itself. Such decoration is therefore part of an immovable support, ‘completely and unavoidably physically dependent’ on it (Cather, 2010). This is therefore the case of wall paintings, among other decorative architectural surfaces, such as reliefs and mosaics. Wall paintings are particularly complex systems, composed of multiple layers of materials, connected through porosity one to the other and to the external environment. Such physical open system is hardly controllable, and often causes of degradation cannot be removed. In addition to this, wall paintings are potentially very vast, often reaching hundreds of square meters, and extremely heterogeneous, both topographically and stratigraphically, i.e. their original materials and condition may significantly vary from one area to another. All these factors make the conservation of wall paintings extremely challenging (Cather, 2010). Among the deterioration phenomena which may be encountered, delamination – a lack of adhesion between plaster layers, or support and plaster –, when unstable, is particularly dangerous for the integrity of wall paintings, and challenging to address.