AIC's 47th Annual Meeting

A new bonding system for the reinforcement of paintings made on textile supports will be presented. These are self-supporting, flexible meshes produced of a series of pure and well-established conservation adhesives. The main focus will be set on methylcellulose. Technically, the procedure involves positioning of the mesh in dry state, activation with controlled supply of moisture or solvents, and application of pressure to trigger the bonding. This approach enables an exceptionally precise application, thus minimizing the risks related to conventional use of liquid solutions, namely shrinking, stiffening and darkening of textiles. Furthermore, compared to hot-seal adhesives, methylcellulose meshes are particularly suitable for paintings that are sensitive to heat as no elevated temperatures are required for the activation. Adhesive meshes were developed particularly for the bonding of canvas, providing a regular, permeable adhesive pattern. Despite the lack of a carrier material, the meshes have a certain stiffness that allows to access detached layers through gaps or slits. Based on the successful application of sturgeon glue meshes (Konietzny, 2015), the method is now being complemented with meshes made from methylcellulose. This cellulose ether is among the most constant, ageing-resistant (Feller and Wilt, 1990) and, compared to popular synthetic polymers, sustainable adhesives used in conservation. Reliable adhesion has already been reported for canvas (Sindlinger-Maushardt and Petersen 2007, Bosshard-Van der Brüggen, 1972), wood (Döll, 1997) and leather (Gottsman, 2009) among other materials. The technique excels by its controllability and reversibility, when compared to other current practices. Unlike the common application in solution at low concentration, methylcellulose meshes are implemented as a solid that is activated with water or moisture, assuring the adhesive to discretely remain in the joint and create a mechanical bond without penetrating the textile. By varying the activation parameters, notably the amount of water, adhesion can be manipulated up to a remarkably high strength that was empirically found to be as strong as Beva® 371 films of 65 µm thickness. Meanwhile, the technique is being deployed by renowned institutions like the Swiss Institute for Art Research and the Swiss National Museum in Zurich (Switzerland) as well as the Doerner Institute in Munich (Germany). Detailed examination of adhesive mesh bonding and the development of meshes made from other materials such as acrylic adhesive to be used for water-sensitive works of art are the objectives of a current research project [Innosuisse No. 27510.1]. It is based at the Bern University of Applied Sciences (Switzerland), carried out in cooperation with APM Technica AG (Switzerland), the Dresden University of Fine Arts (Germany) and is financed by the Swiss Federal Innovation Agency. This paper aims at introducing methylcellulose meshes by presenting two case studies including strip lining and re-adhesion of a detached lining. Different activation strategies by water spray or a humidified capillary non-woven fabric will be demonstrated, both leading to convincing results. Moreover, perspectives of ongoing research and potential implementations in different fields of conservation will be addressed.