Mold growth under near-saturated preservation environment of unearthed relics within archaeological museums

Mold is an important deterioration risk to in situ preserved relics since they require a high relative humidity (RH) preservation environment to maintain their original state as before unearthed. However, few studies have been conducted to characterize mold growth on the surface of inorganic unearthed sites under saturated RH conditions. In this study, four groups of soil samples with different salt content were placed in different RH environments to assess mold growth under near-saturated conditions based on previously completed simulations of unearthed sites in an exhibition hall and an experimental platform for the environmental control system to preserve cultural relics. The very high RH (> 99%) of the near-saturated environment had a higher inhibitory effect on mold growth compared with the RH of 80–90%, which is favorable for mold growth. This inhibitory effect was not remarkably different from that of a dry environment. As salt content is proportional to mold growth on the surface of unearthed sites, a reduction in the former significantly inhibited the latter. This study provides basic knowledge about the characteristics of mold growth for unearthed sites in a near-saturated environment and proposes novel ideas for its prevention.