Cultural heritage is the priceless value of a place or a country. Cultural heritage objects are subject to various aging and degradation processes that lead to a deterioration of their quality. For this reason, we resort to consolidation which is one of the most important conservation procedures that these objects need to survive over time. Consolidation involves the use of consolidants which are various binders dispersed in a solvent that is applied to the damaged layer of the materials to restore the lost cohesion between the particles. Ca(OH)2-based consolidants are one of the most commonly used materials for consolidation due to their chemical compatibility with carbonate-containing objects. Among the most promising Ca(OH)2-based consolidants are Ca(OH)2 nanoparticles. Consolidation with nanoparticles is based on a carbonation reaction. During carbonation, Ca(OH)2 particles react with CO2 from the air resulting in the formation of CaCO3. This binds the loose particles and fills the cracks solidifying the porous material. Nanoparticle consolidation is very effective for surface consolidation. Commercial nanoparticle-based products include CaLoSil® and Nanorestore®, which have been used in various studies and projects. Despite all their good properties, problems arise when deep consolidation is required. For this purpose, an aqueous solution of calcium acetoacetate – Ca(OAcAc)2, also known as CFW (Consolidant Formulation Water) – was developed as part of the HEROMAT project. Calcium acetoacetate decomposes in the presence of water to calcium carbonate, carbon dioxide, and acetone. The consolidation effect is achieved when CO2 and acetone evaporate and the newly formed CaCO3 particles fill the damaged substrate. CFW penetrates better into the substrate, needs to be applied less often, improves mechanical properties, and has no significant effect on color compared to nanoparticles.
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