Biocleaning of Cultural Heritage stone surfaces and frescoes: which delivery system can be the most appropriate?

The use of the advanced biotechnology of microbiological systems for the biological cleaning of Cultural Heritage (CH) has been recently improved and optimized taking into account different factors. Biocleaning systems have been indeed applied to historic buildings, statue,s and frescoes. Such application has developed new techniques and optimised and refined the existing systems. These systems remove altered forms like sulfate and nitrate crusts and organic substances like animal glue in a more effective, less invasive way than the traditional cleaning techniques. This review focuses on several delivery systems (sepiolite, hydrobiogel-97, cotton wool, carbogel, mortar and alginate beads, agar, and arbocel) used for the biocleaning of Cultural Heritage, comparing their main properties and characteristics, making a critical evaluation on how easy they can be applied, and on their future potentiality as ready-to-use and risk-free formulates. Therefore, this review will help conservation scientists, conservator-restorers, and researchers in the field to choose the most appropriate delivery system for any specific applications.