Glass is by definition a metastable material and undergoes continuous transformations due to different physical and chemical processes, further enhanced by its peculiar composition and the environmental conditions to which they have been exposed. Considering this peculiarity, the consolidation or preservation treatment must be designed to be effective for each peculiar glass composition, degradation state and conservation conditions. Nowadays, the conservation of archaeological and historical glass is still a challenging and open issue for the cultural heritage community because of the poor material compatibility and the toxicity of thermoplastic and thermosetting resins that are widely adopted by conservators worldwide. The results of the characterisation analyses are a necessary base for the specific design of appropriate strategies for the protection and consolidation of glassy materials. Data-driven innovative formulations with highly enhanced performances compared to state-of-the-art are developed to be 100% compatible with the glass substrate, in opposite to the widely used but poorly working polymeric materials. The recent breakthroughs in nanotechnology provide great advantages and new tools to develop approaches able to dramatically overcome major limitations of current technology. Transparent, nanostructured and superhydrophobic coatings to be applied on the artefacts' surface are key to strongly limiting the mechanisms and the ongoing processes leading to glass corrosion and degradation.
Frescoes, especially those preserved in situ, are exposed to the harsh conditions of the outdoor environment and require the development of protective systems, specifically designed for the peculiarities of these artworks. The development of tailor-made protective coatings for Roman frescoes is highly needed as there is a complete absence of specific products for this aim and this issue requires immediate action. As the degradation can be of chemical, physical and biological nature (fading, saline efflorescence, detachment of the pictorial layer and microbiological colonies among the most common forms), multi-functional formulations against the detected forms of degradation are needed. To achieve this ambitious goal coupled with the highest restoration standards and the absence of toxicity for the environment and the operators, innovative approaches are developed leveraging the great advances recently achieved by nanotechnology and green chemistry.
Archaeological metals have rested for hundreds of years in an aggressive environment, suffering significant alterations in their constituent materials with the formation of thick and complex layers of corrosion products. Some of these products may be unstable and can auto-catalytically perpetrate a degradation process (as in the case of the so-called bronze disease). Others can eventually reach the equilibrium while buried but may be destabilised by the abrupt change in the conservation environment after excavation. Even when the altered compounds are inert, this ‘coat’ of corrosion products plays an active role as it constitutes the interface between the bulk of the metal object and the surrounding environment.
Based on the extensive diagnostic activities of the CCHT, innovative and out-of-the-box solutions for the conservation of archaeological copper-based metals are developed. The designed products will overcome the limitations of the widely used polymeric-based solutions. They will suppress the latent corrosion phenomena and prevent the onset of new ones, without the drawbacks on durability that current approaches based on polymers suffer. This will empower conservators with new tools for the preservation of historical data together with the physical integrity of the metal assets for future generations.
The deterioration of ancient paper is a complex problem for the conservation of cultural heritage. Paper is an extremely heterogeneous and delicate material mainly composed of cellulose and its composition strongly depends on the specific production technology.
From a chemical perspective, cellulose degradation can be mainly seen as the combination of two interdependent reactions: acid hydrolysis (which implies the cleavage of the glycosidic bond in the amorphous regions of cellulose), and oxidation of the β-D-glucopyranose units (with the subsequent development of several chemically different degradation compounds).
From a macroscopic perspective, hydrolysis weakens the mechanical properties of the sheet, whilst oxidation induces the characteristic colour change.
The kinetics of those chemical reactions is severely affected either positively or negatively by both internal agents (e.g. basic lime reserve, corrosive inks), and external factors (e.g. humidity content, mould attack).
We devote strong effort to the consolidation of the writing support as the first and crucial step needed for further treatments.
Our extensive characterization of paper documents and deterioration processes is the elective starting point to investigate the promising consolidation properties of new formulations. We focus on the great possibilities given by nanostructured cellulose, a promising material that can strongly slow down or halt deterioration whilst guaranteeing great combability with the pristine material.
Moreover, cellulose can be sourced from renewable feedstock and is the most abundant biopolymer on earth, thus guaranteeing the sustainability of our approach whilst providing abundant and affordable availability. This is a key point as hundreds of thousands of paper-based documents stored worldwide are in need of consolidation treatment.
Due to the complexity of mosaics, restorers face great difficulties to define satisfactory strategies for optimal conservation. Loss of tesserae represents one of the most compelling issues. This phenomenon is caused by climatic variation and further worsened by the presence of capillary water and ambient humidity. In order to enhance the cohesion of tesserae and the strata below and to repair fractures, restorers are forced to use commonly available injection mortar. However, this material is not specifically designed for the peculiar issues of mosaics preservation and can create several problems. Considering these compelling points, new specific injection mortar formulations need to be designed in order to improve the adhesion of tesserae and reduce damage induced by water. Knowledge gained by the characterization phases of roman mosaics is fundamental and provides the necessary means to develop new formulations with specific characteristics matching the ones of the original pieces under examination. The great opportunity offered by nanotechnology is necessary to provide the desired properties by adding key functionalities and long-lasting resistance. Addition to the mortar of natural compounds such as plant-derived hydrogels can dramatically improve the mechanical and elastic properties of the mortar. Multidisciplinary competencies are necessary in order to design, test and prototype innovative and disruptive formulations of mortars. Cultural heritage, scientific knowledge and materials innovation have joined forces for the common goal of the conservation of splendid mosaics.