New conservation products for historic building materials

Natural weathering of historic surfaces is made worse by increased atmospheric pollution and accelerated climate change. Moreover, the use of inappropriate commercial preservatives has been identified as a major contributor to building deterioration. Therefore, there is the demand to improve the current restoration products and methodologies or to develop new valid alternatives for the conservation and preservation of monuments, safeguarding their cultural values and improving their future usability.

The EU-funded NANOMATCH (Nano-systems for the conservation of immoveable and moveable polymaterial cultural heritage in a changing environment) project aimed to address this problem by creating complex, nano-structured materials that are specifically designed to preserve historic wood, stone, stone-like and glass materials.

Nano-suspensions of calcium alkoxides, precursors of the corresponding carbonate, were synthesised to increase the strength in stone and stone-like materials, as well as to provide alkaline supply in wooden substrates. Molecularly dispersed aluminium alkoxide, precursor of Al2O3, already developed in the EU project CONSTGLASS, was optimised to allow the penetration in the smallest cracks (< 5μm) of corroded glass.

The new treatments were assessed on a variety of selected substrates in terms of workability, efficacy, compatibility and durability in comparison with a range of commercial products. Treated model samples and degraded historical substrates were first analysed in laboratory and then before and after one-year exposure on the field, through cases studies in places of worship in Germany (Cologne Cathedral), Spain (Oviedo Cathedral), Italy (Santa Croce Basilica in Florence) and Romania (Stavropoleos Monastery in Bucharest). The impact on human health and the environment was also tested.

Finally, the optimal processing parameters for industrial production were defined and an economic cost-benefit analysis of the new products was performed. An exploitation plan mainly tailored to small and medium-sized enterprises was also produced. This led to a business model that assesses their marketability and the possible risks during commercialisation.

By developing advanced and sustainable nano-structured materials as an alternative to conventional products, NANOMATCH will help reverse the decay of historic materials. The project will ultimately improve the preservation of Europe's valuable built heritage. See the project's video here.