By Craig Kennedy, School of Energy, Geoscience, Infrastructure and Society, Heriot Watt University, Edinburgh
Following several years undertaking analysis of a variety of historic materials, in 2006 I entered the field of built heritage conservation as a scientist working with Historic Scotland. There, I was fortunate to share an office and lab space with the applied conservation team who spent their time working on properties in state care, or on individual objects that were brought in to the conservation centre for remedial work.
Importantly, I got a real sense that there was a specific set of rules that the built heritage community worked to, and it defined many of the decisions that they took when approaching a new piece of work. These rules were not difficult to track down. Building conservation philosophy is extremely well documented, including international charters form bodies such as ICOMOS, the SPAB Manifesto and various books, journal papers and the like.
The Role of Science in Conservation Charters
Examining the key conservation documents revealed that science, far from being an add-on to a conservation project, was central to almost every major charter. One such charter is the ICOMOS Venice Charter (1964), a highly important document which helped shape and define conservation philosophy for the last half century. This charter consists of 16 articles in all; article 2 states
“The conservation and restoration of monuments must have recourse to all the sciences and techniques which can contribute to the study and safeguarding of the architectural heritage.”
Indeed, ICOMOS went further and in 2003 published the charter “Principles for the analysis, conservation and structural restoration of architectural heritage” which considered the role of research and diagnosis more fully. Other key documents including British Standard 7913 and the ICOMOS Burra Charter also state explicitly that science and research should be utilised as part of the conservation process.
Recommendations for Better Use of Science in Building Conservation
In a recent article1, I considered how best to improve the working relationship between scientists and heritage professionals. It was clear to me that science most certainly has a central role to play in conservation, but exactly how should this work in practice? Specifically, how can it work in such a way that meets the heritage managers’ concerns and also allows for meaningful scientific investigations? These 7 recommendations are the result of this work.
- A team-based approach to developing evidence-based conservation
Building conservation projects regularly employ a range of experts, from architects to conservators. Scientists should be included as an integral part of the team, with a specific remit to investigate the building and help to inform its physical conservation.
- Preference for non-destructive or micro-destructive testing
Heritage managers are reluctant to allow sampling; “retention of historic fabric” is a key conservation principle. How can scientists get around the need to take samples from the site? One solution is in the recent advancements of portable scientific technologies, which allow science to be taken to the site. Scientific techniques such as near-infrared spectroscopy (NIR), X-ray fluorescence (XRF), hyperspectral imaging, thermal imaging, laser scanning, Raman spectroscopy, and many others can now be done on-site in a way that wasn’t possible even a decade ago.
Sometimes these techniques are not enough, however – say, when analysing a mortar sample, you may need to carry out X-ray diffraction. This involves sampling – the best approach here is to take many small samples from across the site. Such micro-testing is already in place in other sectors of heritage, for example, micro-drilling of parchment for document conservation.
- Gathering large data sets
Historic buildings tend to be a collection of various materials combined to form the whole. Additionally, these materials may be subjected to microclimates which cause localised weathering. To better understand the deterioration and condition of a building, data should be taken from across the whole site if possible. This reduces the chances of a small number of samples skewing results.
- Use of modern analogue materials
It’s not desirable to conduct destructive or harmful tests on historic material. As such, using test materials to carry out experiments in lab conditions is encouraged. For example, the research team at Queens University, Belfast, constructed sandstone test walls in Derrygonnelly to understand weathering; Historic Scotland built a sandstone test wall to subject to extreme salt damage. These examples allow us to better understand material decay without destroying an item of cultural value.
- Stress testing (artificial or accelerated ageing)
The terms ‘artificial’ or ‘accelerated’ ageing are a little misleading. No test yet has been devised that can accurately predict the condition of a building material years in to the future on the basis of applying laboratory stresses. As such these tests should be re-named ‘stress tests’. They can provide valuable information, for instance on whether a new conservation treatment will improve or hamper the durability of a building material.
- Openness of access to experimental data
Conservation records can be in-depth and highly detailed, including photographs and drawings of the site and areas of decay. When scientific work is carried out on a site, this data should be included in the conservation records. That way, when future work is being carried out scientists and conservators will have access to as much data as possible to inform their actions. Publication of scientific work should also be encouraged; the overall knowledge base regarding traditional building materials must be increased.
- Integrating heritage science as part of the overall heritage experience
People are naturally interested in the investigative side of conservation. Highlighting this as part of conservation work will both inform the public and improve the standing of heritage science. Heritage bodies often produce magazines and articles highlighting conservation works; these should (and in some cases already do) include science.
1. Kennedy (2015) The Role of Heritage Science in Conservation Philosophy and Practice, The Historic Environment 6:3, p214-228