Gold leather: Symposium in Maastricht

Gold leather was the focus of an international symposium in spring 2016. Experts met at the Stichting Restauratie Atelier Limburg (SRAL) to discuss the technical art history of the material, material dynamics, conservation challenges and diagnostics. The symposium was supported by the Netherlands Organization for Scientific Research (NWO) on the initiative of the Netherlands Institute for Conservation, Art and Science (NICAS).

The 17th and 18th centuries are considered the “Golden Age” of gold leather in the north and south of the Netherlands. Although this material was once as famous as Delft pottery, unfortunately much of it has been lost. The reasons for this are renovations, material degradation and a lack of knowledge about conservation methods. The current generation of technical art historians, conservators and scientists are working together to preserve these objects and their cultural significance for future generations.

At a Goldleder symposium in spring 2016, conservators and scientists came together in Maastricht to discuss the future of this endangered cultural asset and its future conservation and restoration methods.

The discussion on the subject of “Technical Art History” came to the conclusion that analyses must be carried out using the most modern methods in a wider European context on objects left in their original state: in their original location, well documented and with few conservation interventions. The data thus obtained will be compared with archival studies of the most important manufacturing centers (Mechelen, Venice, Cordoba) by examining inventory lists, transport of craft objects and the connection between workshops. A database for research data and source research is urgently needed.

In the area of ‘material dynamics’, it was found to be a concern that the ageing process of gold leather is neither well studied nor understood. In some cases, leather panels age at very different rates in the same room.

The challenges

Cleaning and dealing with the effects of previous conservation efforts were key areas of focus in the topic of conservation challenges. There is extensive literature on cleaning in general, but these methods may not be suitable for gold leather. The second major difficulty is dealing with previous treatments. Feeding, the application of new varnish or treatments with oil or wax can permanently alter the objects and cause gold leather to darken. Last but not least, the decreasing flexibility of old leather remains a problem for which no satisfactory solution has yet been found.

The symposium also dealt with the topic of “diagnostics”. The latest technical equipment makes it possible to examine some art historical and conservation issues more closely. For example, peptide mass fingerprints (PMF) can be used to determine which animal was used for leather production (cow, goat, sheep). The experts found it particularly important to identify the materials, adhesives, protective layers and metal leaf compounds used in order to gain insights into the origin and trade of materials. More detailed information on the stratigraphy of gold leather can now be obtained thanks to optical coherence tomography (OCT) – a technique originally developed for medical applications – and spectral distributions can be mapped using hyperspectral imaging.

The future of gold leather

Many gold leather objects are in a precarious condition or have already been lost. Due to the small expert community for gold leather, it is all the more important to work together nationally and internationally to gather knowledge and experience. Ideally, this would create a digital platform on production techniques, effects of successful and less successful conservation efforts, databases on materials and samples and access to diagnostic equipment and willing experts to support these activities. It is important to raise awareness that gold leather is an endangered part of our cultural heritage.

Read more about leather conservation in Restauro 7/2016. Available here from October 10, 2016.