The application of biocides is one of the most important means to control microbial deterioration. Commercial agents such as Biotin® T and Preventol® RI 80 (isothiazolinones) have been widely applied on inorganic substrates that comprise cultural heritage materials, such as stone and mortars47,48. The active agent, isothiazolinones, is considered to be not only effective but also preventive when applied to paper and stone materials49. Borate buffer solution (BBS) has also been used to mitigate microbial deterioration following the full-scale excavation of the shipwreck that began in 2013. In addition to these biocide agents, we selected four additional agents, whose main component is isothiazolinones, in order to test their biocidal efficacy in the laboratory (Supplementary Table 4).