Skip to main content
European Commission logo print header

Nanomaterials for conservation of European architectural heritage developed by research on characteristic lithotypes

Periodic Reporting for period 2 - NANO-CATHEDRAL (Nanomaterials for conservation of European architectural heritage developed by research on characteristic lithotypes)

Reporting period: 2016-12-01 to 2018-05-31

We are generally led to believe that stone and stone artefacts are materials destined to last forever, but this is not the case with most of our traditional buildings and sculptures. Above all during the Middle Ages, the tendency was to choose raw materials based on the availability of quarries near the shops and the greater softness and workability of the stones. For this reason, in the long-term many stones resulted to be too delicate and sensitive to atmospheric agents. Also in the modern and contemporary age, the choice of using beautiful stones is driven by economic, cultural and aesthetic reasons, but the issues of protecting such monuments and monumental buildings is often not satisfied by the availability of suitable products and standard procedures.
The Nano-cathedral project addressed the issue of conservation and protection of such stone monuments, as fundamental and tangible assets of our European cultural heritage. The multidisciplinary effort of 19 partners from 7 European Countries led to the development of innovative consolidating and protective products, by targeting the unique properties of nanoparticles, biopolymers and biologicals to the specific needs of different lithotypes, decay phenomena and environmental conditions. Five Gothic cathedrals scattered throughout Europe plus the Oslo Opera House served as case studies and trial sites, allowing to test the efficacy of the novel treatments in different stones and conditions.
The activities carried out along the three-years-long innovation project, furthermore, allowed to increase the knowledge about stone decay, the relevance of selecting the best application method for each type of product and stone, and the importance of monitoring to track the long-term effect of treatments. The results will be exploited to increase scientific knowledge, to contribute to standards development and to push economic growth and competitiveness of European SMEs. The best-performing novel materials will be available to the market after the end of the project, as part of a custom-made service which allows the end users to target the specific needs of each specific stone, taking into considerations the lithotype, the decay conditions and the application procedure.
Nano-cathedral also provided invaluable learning and training opportunities for the scientific community, practitioners and citizens.
Nano-cathedral has employed the latest advancements in nanotechnology, biotechnology and materials science to develop two types of products, which are specific for two phases of stone conservation:
Surface consolidation (a material that penetrating by capillarity into the micro-structure of the decayed stone, is able to strengthen it by replacing lost original mineral bridges, and partially recovering lost mechanical properties).
Surface protection (a material that penetrating by capillarity into the micro-structure of the stone, is able to prevent the entrance of liquid water, without any change in aesthetical, optical and chemical properties of the substrate).
The innovative products were specifically developed for 6 specific lithotypes, as representatives of the cathedrals partners of the project, shown in figure 1.
During the first year, over 40 materials were developed by COLOR, CS, TECNAN, KIT and INSTM, with the aim to consolidate or protect the different lithotypes, based on multiple considerations:
1. the characteristics of the 6 lithotypes
2. the decay phenomena of the stones in the trial monuments
3. the environmental/weather conditions for the different monuments (which influence the mechanisms of decay)
During the second year, over 30 products underwent a thorough investigation and characterization phase, with tests performed in specialized University research centers on stone samples from the 6 lithotypes. This second testing phase allowed to select the best performing products to be tested in trials in-situ, directly on the monuments stones.
The last year was focused on real-life demonstration of selected products on the partners cathedrals of Cologne, Gent, Vitoria, Vienna and Pisa, and the Oslo Opera House. Although the necessity for further monitoring at mid-term and long-term will be necessary to fully characterize the products, the results from the demonstrations trials were satisfactory, leading to future exploitation of such products on the market.
The first products that Nano-cathedral will propose to the market are both finished products and intermediates, as shown in figure 2.
The Nano-cathedral products, procedures and knowledge will allow conservators to have one valid allied for the treatment of stone buildings, with practical and affordable solutions in terms of cost and/or complexity of operation by those who will use the materials and techniques that have been developed. In fact:
• costs will be affordable
• procedures will be provided for each case, as application method is a key issue.
This responds to an actual need from the conservators, as clearly shown by the surveys conducted in the frame of WP6 “Analysis of the socio-economic & cultural impact”. The analysis was carried out both through the study of the available literature, and through original surveys to different stakeholders groups around Europe: stone masons/sculptors, industry representatives, practitionsers and citizens. Results indicate a low satisfaction of stone conservation and protection products and technologies actually present on the market, therefore confirming the expectation that the Nano-cathedral products and standards will offer a solution that will contribute to conservation and safeguard of European cultural heritage.
The results from the project confirm that the economic impact for the Nano-cathedral companies will be positive on industry. For the consortium partners it will be based on the adoption of the strategy to link the products to a service, with the aim to create a complete support to restorers and building owners, with:
A systematic approach to correlate the lithotype of the material to be protected and the final formulation (tailor-made formulates).
An extension to modern monuments (such as the trial site OSLO OPERA HOUSE), enabling the employment of products also on smaller buildings; public civil buildings; private monuments; stone elements inserted in modern buildings.
The reliability of the products which have been developed and tested in such a multidisciplinary effort as the Nano-cathedral project.
The impact on tourism industry will also be positive, as suggested by the surveys conducted in WP6 showing that the public largely prefers well conserved and preserved documents and thinks that technological development is important also for this purpose.
Workshops and training courses were performed to bridge the gap between specialisation and common application and to promote the acceptance of using the novel materials in general. The special tutorial at the cathedrals’ workshops demonstrated the proper application and handling of the tailor-made materials at each cathedral site with the lithotypes that have been chosen for the test phase. Surveys conducted at the workshops allowed to confirm that practitioners expectations new products are high, and that they have the potential to be successful on the market.