ISSN: 2067-533X INTERNATIONAL JOURNAL OF CONSERVATION SCIENCE Volume 11, Issue 2, April-June 2020: 405-424 www.ijcs.ro SYNERGIC USE OF AMMONIUM OXALATE AND DI-AMMONIUM PHOSPHATE IN THE PROTECTION AND CONSOLIDATION OF CARBONATE MATERIALS Mauro MATTEINI 1 , Fabio FRATINI 1 , Silvia RESCIC 1 , Mirella BALDAN 2 , Lucrezia CAMPANA 3 , Oana Adriana CUZMAN * 1 CNR-Institute of Heritage Science,Via Madonna del Piano, 10, 50019 Sesto Fiorentino (Florence), Italy 2 R&C Art Srl, Via Retrone, 39, 36077 Altavilla Vicentina (Vicenza), Italy 3 Accademia delle Belle Arti di Verona, Via Carlo Montanari, 5, 37122 Verona, Italy Abstract The aim of this this research is to verify the suitability of some treatments based on ammonium oxalate and ammonium phosphate for the consolidation and protection of the internal entrance of Palazzo Verità Montanari (1583) in Verona, made of Avesa Stone. Different application protocols of the two products have been compared (the product alone, in mutual sequence, in mixture). The efficacy and limitations of the treatments are discussed on the basis of the results obtained with various types of diagnostic analyzes, invasive and non-invasive, as part of a laboratory experimentation carried out on specimens of the same carbonate stone. Keywords: Conservation; Consolidation; Ammonium Oxalate; Di-Ammonium Phosphate; Carbonate Materials Introduction The present research concerns an experimentation carried out on several possible consolidation treatments to be adopted for the conservation of the internal entrance of Verità Montanari Palace (1583) in Verona. The Palace was commissioned to an unknown author by Giacomo Verità, to commemorate and glorify his father, Gerolamo Verità, a well-known political figure and the first Veronese poet that use the vernacular in his writings [1-2]. The internal entrance of the Palace was realized in Avesa stone, an organogenic limestone. The consolidation of ancient architectural stone façades is one of the most delicate tasks in the conservation of stone artefacts. Consolidation, in fact, is an intrinsically irreversible operation and before deciding which treatments to use – whose materials will remain permanently inside the stone - severe and critical attention is required. Once the stones have been quarried and shaped to be finally put in place, they will continue the natural decay process already begun in the outcrop [3-4]. The laying of a stone implies a new context in which the stone is subjected to new stress, sometimes in contact with other materials with different physical-chemical-mechanical characteristics that may accelerate the natural process of alteration or that may trigger new decay phenomena. The decay of stone materials manifests in different ways (scaling, pulverization, etc.), depending not only on the environmental conditions but also on the intrinsic stone characteristics related with the genesis * Corresponding author: oanaadriana.cuzman@cnr.it