Since the 1990s the research lab at Heriot-Watt University has engaged in research to understand the decay, maintenance, repair, energy usage, carbon footprint and conservation of historic buildings. Whilst this research has spanned diverse areas, there have been two key themes: low carbon cementitious materials such as lime mortars, and archaeological and historic glass.
Taking the first of these, mortar selection is an important aspect in ensuring that historic buildings do not deteriorate at an accelerated rate. Cementitious materials can act as mortar joints between stone blocks or as a render that covers an entire wall or section of wall. As such, exterior walls of historic buildings are an aggregate of materials that are chemically and mechanically joined together.
As historic mortars weather away, they are replaced by modern equivalents. However, these equivalents may themselves be a cause of decay. Much depends on the material properties of modern mortars which are designed with ease of use and low cost in mind, rather than the properties of the material and long-term prospects of conserving built heritage. For instance, if a mortar joint connecting porous sandstone is impervious to water and has low porosity, the surrounding stone will decay more quickly. There are numerous examples of historic buildings that have undergone extensive, rapid and serious decay because of the incorrect selection of mortars.
For almost thirty years the Heriot-Watt lab has undertaken analysis of cementitious materials to determine their physical properties and potential impact on historic buildings. This work has helped conservators, conservation architects and heritage bodies to understand the materials available and make an appropriate selection. This has helped preserve a wide range of historic buildings, from castles and monuments to townscapes and private residences.
However, much of the equipment used to analyse these materials is now broken or outdated. The first part of this funding is proposed for use in replacing and upgrading the heritage science lab at Heriot-Watt so that it is capable of accurately understanding cementitious materials for use in repair, maintenance and conservation of historic buildings.
The second element of funding proposed is to fund the purchase of a portable X-ray fluorescence system for the analysis of glass and other inorganic materials. Since the early 2010s the heritage science group at Heriot-Watt has used X-ray fluorescence systems to analyse a range of materials, but most notably historic and archaeologically excavated glass.
There are three elements to this research: in situ dating of window glass from historic buildings; understanding the provenance and manufacture of glass recovered from archaeological dig sites, primarily from the Medieval period; and analysis of glass collections from museum settings.
Heriot-Watt does not currently own a portable X-ray fluorescence system. In recent years the heritage science group have borrowed and rented instruments. However, these arrangements cause significant challenges. Firstly, the owners of the instruments that were kindly loaned to the Heriot-Watt lab placed significantly restrictive conditions on their use. The only time the Heriot-Watt lab was able to undertake in situ analysis was when renting a system from a manufacturer. This rental lasted only a few days, causing issues with project programming, trying to rapidly assess historic buildings in a rushed and hurried manner.
This funding will greatly benefit the activities at the Heriot-Watt heritage science lab, allowing for high quality analysis of materials used to preserve and understand our built heritage. Analysis will be at a higher quality, with greater throughput of samples leading to a significant improvement in research outcomes for the lab such as better advice to conservators, more publications and improved chances of winning grant funding.